Medulla Oblongata
Brain Stem
Lateral Medullary Syndrome
Thermoreceptors
Kidney Medulla
Prolactin-Releasing Hormone
Reticulum
Spinal Cord
Brain
Autonomic Pathways
Solitary Nucleus
Hypothalamus
Respiration
Reticular Formation
Cerebellum
Chemoreceptor Cells
Magnetic Resonance Imaging
Vagus Nerve
Cats
Sudden Infant Death
Germinoma
Neurons
Rats, Inbred Strains
Pressoreceptors
Scrapie
Brain Chemistry
Rats, Sprague-Dawley
Proto-Oncogene Proteins c-fos
Immunohistochemistry
Aneurysm, Ruptured
Norepinephrine
Sympathetic Nervous System
Pons
Rats, Inbred WKY
Central Nervous System
Serotonin
Rats, Wistar
Carbon Dioxide
Rats, Inbred SHR
Sheep
Brain Neoplasms
Tissue Distribution
RNA, Messenger
Fire Extinguishing Systems
Hypericum
Firefighters
Beetles
Fossil Fuels
Trans-synaptically induced bursts in regular spiking non-pyramidal cells in deep layers of the cat motor cortex. (1/1851)
In deep layers of the cat motor cortex, we have investigated the properties of neurons displaying trans-synaptically induced bursts. In in vivo experiments, extracellularly recorded burst neurons were separated into two subtypes based on their dependence on stimulation sites, the medullary pyramid or the ventrolateral (VL) thalamic nucleus, from which bursts of 10-20 spikes were triggered. The spike amplitude attenuation and frequency adaptation during a burst were more prominent in pyramid-dependent burst neurons than in VL-dependent burst neurons. Intracellular recordings in in vivo experiments revealed that pyramid-dependent bursts emerged from a long-lasting depolarization, while each spike during a VL-dependent burst was narrow in half-width and was followed by a fast AHP, similar to fast spiking neurons. In in vitro slice experiments, intracellular recordings were obtained from neurons that displayed a burst of attenuated spikes emerging from a long-lasting depolarization, and were also obtained from fast spiking neurons. They were morphologically recovered to be multipolar cells with sparsely spiny dendrites and local axonal networks, suggesting that they are inhibitory interneurons. The multipolar neurons displaying bursts of attenuated spikes may mediate the recurrent inhibition of pyramidal tract cells. (+info)Eye movement deficits following ibotenic acid lesions of the nucleus prepositus hypoglossi in monkeys II. Pursuit, vestibular, and optokinetic responses. (2/1851)
The eyes are moved by a combination of neural commands that code eye velocity and eye position. The eye position signal is supposed to be derived from velocity-coded command signals by mathematical integration via a single oculomotor neural integrator. For horizontal eye movements, the neural integrator is thought to reside in the rostral nucleus prepositus hypoglossi (nph) and project directly to the abducens nuclei. In a previous study, permanent, serial ibotenic acid lesions of the nph in three rhesus macaques compromised the neural integrator for fixation but saccades were not affected. In the present study, to determine further whether the nph is the neural substrate for a single oculomotor neural integrator, the effects of those lesions on smooth pursuit, the vestibulo-ocular reflex (VOR), vestibular nystagmus (VN), and optokinetic nystagmus (OKN) are documented. The lesions were correlated with long-lasting deficits in eye movements, indicated most clearly by the animals' inability to maintain steady gaze in the dark. However, smooth pursuit and sinusoidal VOR in the dark, like the saccades in the previous study, were affected minimally. The gain of horizontal smooth pursuit (eye movement/target movement) decreased slightly (<25%) and phase lead increased slightly for all frequencies (0.3-1.0 Hz, +/-10 degrees target tracking), most noticeably for higher frequencies (0.8-0.7 and approximately 20 degrees for 1.0-Hz tracking). Vertical smooth pursuit was not affected significantly. Surprisingly, horizontal sinusoidal VOR gain and phase also were not affected significantly. Lesions had complex effects on both VN and OKN. The plateau of per- and postrotatory VN was shortened substantially ( approximately 50%), whereas the initial response and the time constant of decay decreased slightly. The initial OKN response also decreased slightly, and the charging phase was prolonged transiently then recovered to below normal levels like the VN time constant. Maximum steady-state, slow eye velocity of OKN decreased progressively by approximately 30% over the course of the lesions. These results support the previous conclusion that the oculomotor neural integrator is not a single neural entity and that the mathematical integrative function for different oculomotor subsystems is most likely distributed among a number of nuclei. They also show that the nph apparently is not involved in integrating smooth pursuit signals and that lesions of the nph can fractionate the VOR and nystagmic responses to adequate stimuli. (+info)The fine structural organization of the cuneate nucleus in the monkey (Macaca fascicularis). (3/1851)
The fine structure of the cuneate nucleus of the monkey (Macaca fascicularis) has been studied. The neurons were classified into three groups according to their nuclear morphology, the arrangement of the rough endoplasmic reticulum (RER) and the appearance of the Golgi complexes. Group I neurons had a regular nucleus and contained abundant cytoplasm in which were found well-developed RER and Golgi complexes. Group II neurons had a slightly irregular nucleus and a variable arrangement of the RER and Golgi complexes. Group III neurons were characterized by a deeply indented nucleus, and scanty cytoplasm in which the cytoplasmic organelles were poorly developed. Group II neurons were the most commonly encountered while Group I neurons were the rarest. Axon terminals contained either round of flattened vesicles. Axon terminals and dendrites commonly formed synaptic complexes. In one type the axon terminal, containing round vesicles, formed the central element, which is presynaptic to the dendrites surrounding it; in addition it is postsynaptic to axon terminals containing flattened vesicles. In another type a large dendrite formed the central element which is postsynaptic to axon terminals containing round or flattened vesicles. (+info)Patterns of phrenic motor output evoked by chemical stimulation of neurons located in the pre-Botzinger complex in vivo. (4/1851)
The pre-Botzinger complex (pre-BotC) has been proposed to be essential for respiratory rhythm generation from work in vitro. Much less, however, is known about its role in the generation and modulation of respiratory rhythm in vivo. Therefore we examined whether chemical stimulation of the in vivo pre-BotC manifests respiratory modulation consistent with a respiratory rhythm generator. In chloralose- or chloralose/urethan-anesthetized, vagotomized cats, we recorded phrenic nerve discharge and arterial blood pressure in response to chemical stimulation of neurons located in the pre-BotC with DL-homocysteic acid (DLH; 10 mM; 21 nl). In 115 of the 122 sites examined in the pre-BotC, unilateral microinjection of DLH produced an increase in phrenic nerve discharge that was characterized by one of the following changes in cycle timing and pattern: 1) a rapid series of high-amplitude, rapid rate of rise, short-duration bursts, 2) tonic excitation (with or without respiratory oscillations), 3) an integration of the first two types of responses (i.e., tonic excitation with high-amplitude, short-duration bursts superimposed), or 4) augmented bursts in the phrenic neurogram (i.e., eupneic breath ending with a high-amplitude, short-duration burst). In 107 of these sites, the phrenic neurogram response was accompanied by an increase or decrease (>/=10 mmHg) in arterial blood pressure. Thus increases in respiratory burst frequency and production of tonic discharge of inspiratory output, both of which have been seen in vitro, as well as modulation of burst pattern can be produced by local perturbations of excitatory amino acid neurotransmission in the pre-BotC in vivo. These findings are consistent with the proposed role of this region as the locus for respiratory rhythm generation. (+info)Central neuronal circuit innervating the lordosis-producing muscles defined by transneuronal transport of pseudorabies virus. (5/1851)
The lordosis reflex is a hormone-dependent behavior displayed by female rats during mating. This study used the transneuronal tracer pseudorabies virus (PRV) to investigate the CNS network that controls the lumbar epaxial muscles that produce this posture. After PRV was injected into lumbar epaxial muscles, the time course analysis of CNS viral infection showed progressively more PRV-labeled neurons in higher brain structures after longer survival times. In particular, the medullary reticular formation, periaqueductal gray (PAG), and ventromedial nucleus of the hypothalamus (VMN) were sequentially labeled with PRV, which supports the proposed hierarchical network of lordosis control. Closer inspection of the PRV-immunoreactive neurons in the PAG revealed a marked preponderance of spheroid neurons, rather than fusiform or triangular morphologies. Furthermore, PRV-immunoreactive neurons were concentrated in the ventrolateral column, rather than the dorsal, dorsolateral, or lateral columns of the PAG. Localization of the PRV-labeled neurons in the VMN indicated that the majority were located in the ventrolateral subdivision, although some were also in other subdivisions of the VMN. As expected, labeled cells also were found in areas traditionally associated with sympathetic outflow to blood vessels and motor pathways, including the intermediolateral nucleus of the spinal cord, the paraventricular hypothalamic nucleus, the red nucleus, and the motor cortex. These results suggest that the various brain regions along the neuraxis previously implicated in the lordosis reflex are indeed serially connected. (+info)The rostral ventrolateral medulla mediates the sympathoactivation produced by chemical stimulation of the rat nasal mucosa. (6/1851)
1. We sought to outline the brainstem circuit responsible for the increase in sympathetic tone caused by chemical stimulation of the nasal passages with ammonia vapour. Experiments were performed in alpha-chloralose-anaesthetized, paralysed and artificially ventilated rats. 2. Stimulation of the nasal mucosa increased splanchnic sympathetic nerve discharge (SND), elevated arterial blood pressure (ABP), raised heart rate slightly and inhibited phrenic nerve discharge. 3. Bilateral injections of the broad-spectrum excitatory amino acid receptor antagonist kynurenate (Kyn) into the rostral part of the ventrolateral medulla (RVLM; rostral C1 area) greatly reduced the effects of nasal mucosa stimulation on SND (-80 %). These injections had no effect on resting ABP, resting SND or the sympathetic baroreflex. 4. Bilateral injections of Kyn into the ventrolateral medulla at the level of the obex (caudal C1 area) or into the nucleus tractus solitarii (NTS) greatly attenuated the baroreflex and significantly increased the baseline levels of both SND and ABP. However they did not reduce the effect of nasal mucosa stimulation on SND. 5. Single-unit recordings were made from 39 putative sympathoexcitatory neurons within the rostral C1 area. Most neurons (24 of 39) were activated by nasal mucosa stimulation (+65.8 % rise in discharge rate). Responding neurons had a wide range of conduction velocities and included slow-conducting neurons identified previously as C1 cells. The remaining putative sympathoexcitatory neurons were either unaffected (n = 8 neurons) or inhibited (n = 7) during nasal stimulation. We also recorded from ten respiratory-related neurons, all of which were silenced by nasal stimulation. 6. In conclusion, the sympathoexcitatory response to nasal stimulation is largely due to activation of bulbospinal presympathetic neurons within the RVLM. We suggest that these neurons receive convergent and directionally opposite polysynaptic inputs from arterial baroreceptors and trigeminal afferents. These inputs are integrated within the rostral C1 area as opposed to the NTS or the caudal C1 area. (+info)RVLM and raphe differentially regulate sympathetic outflows to splanchnic and brown adipose tissue. (7/1851)
To determine whether neurons in the rostral raphe pallidus (RPa) specifically control the sympathetic nerve activity to brown adipose tissue (BAT SNA), thereby regulating adipocyte metabolism and BAT thermogenesis, the responses in BAT SNA to disinhibition of RPa neurons and to disinhibition of neurons in the vasomotor region of the rostral ventrolateral medulla (RVLM) were compared with those in splanchnic (Spl) SNA, which primarily regulates visceral vasoconstriction. In urethan-chloralose-anesthetized ventilated rats, both acute hypothermia and microinjection of bicuculline into RPa produced significantly larger increases in BAT SNA (542 and 1,949% of control) than in Spl SNA (19 and 24% of control). The enhanced burst discharge in BAT SNA was not coherent with that in Spl SNA or with the arterial pressure (AP) at any frequency except the central respiratory frequency. Microinjections of bicuculline into RVLM evoked increases in Spl SNA (86% of control) and AP (32 mmHg), but reduced BAT SNA to low, normothermic levels. Microinjections of muscimol into RVLM reduced Spl SNA (-82% of control) and AP (-59 mmHg), but did not prevent the increase in BAT SNA after disinhibition of RPa neurons. These results indicate that the neural networks generating BAT SNA in response to disinhibition of RPa neurons are independent of those generating basal Spl SNA and support a model in which sympathetic outflow to tissues involved in thermoregulation and metabolism is regulated by central pathways, including neurons in RPa, that are distinct from those involved in the sympathetic control of the cardiovascular system. (+info)Midline medullary depressor responses are mediated by inhibition of RVLM sympathoexcitatory neurons in rats. (8/1851)
Mechanisms underlying the depressor and sympathoinhibitory responses evoked from the caudal medullary raphe (MR) region were investigated in pentobarbital sodium-anesthetized, paralyzed rats. Intermittent electrical stimulation (0.5 Hz, 0.5-ms pulses, 200 microA) of the MR elicited a mixed sympathetic response that consisted of a long-latency sympathoexcitatory (SE) peak (onset = 146 +/- 7 ms) superimposed on an inhibitory phase (onset = 59 +/- 10 ms). Chemical stimulation of the MR (glutamate; Glu) most frequently elicited depressor responses accompanied by inhibition of sympathetic nerve discharge. Occasionally, these responses were preceded by transient pressor and SE responses. We examined the influence of intermittent electrical stimulation (0.5 Hz, 0.5-ms pulses, 25-200 microA) and Glu stimulation of the MR on the discharge of rostral ventrolateral medulla (RVLM) premotor SE neurons. Peristimulus-time histograms of RVLM unit discharge featured a prominent inhibitory phase in response to MR stimulation (onset = 20 +/- 2 ms; duration = 42 +/- 4 ms; n = 12 units). Glu stimulation of the MR reduced blood pressure (-37 +/- 2 mmHg, n = 19) and inhibited the discharge of RVLM SE neurons (15 of 19 neurons). Depressor and sympathoinhibitory responses elicited by chemical and electrical stimulation of the MR region are mediated by inhibition of RVLM premotor SE neurons and withdrawal of sympathetic vasomotor discharge. (+info)The medulla oblongata is a part of the brainstem that is located in the posterior portion of the brainstem and continues with the spinal cord. It plays a vital role in controlling several critical bodily functions, such as breathing, heart rate, and blood pressure. The medulla oblongata also contains nerve pathways that transmit sensory information from the body to the brain and motor commands from the brain to the muscles. Additionally, it is responsible for reflexes such as vomiting, swallowing, coughing, and sneezing.
Piloerection, also known as "goosebumps" or "horripilation," is a medical term that refers to the erectile response of hair follicles. It's a reflex caused by the contraction of tiny muscles called arrector pili attached to each hair follicle, causing the hairs to stand on end.
This reflex is often associated with cold temperature or emotional responses such as fear or excitement. While it's most noticeable in humans on the arms and back of the neck, it can occur all over the body. In animals, especially those with thick fur, piloerection can make them appear larger and more threatening, which is often a part of their defense mechanism.
The brainstem is the lower part of the brain that connects to the spinal cord. It consists of the midbrain, pons, and medulla oblongata. The brainstem controls many vital functions such as heart rate, breathing, and blood pressure. It also serves as a relay center for sensory and motor information between the cerebral cortex and the rest of the body. Additionally, several cranial nerves originate from the brainstem, including those that control eye movements, facial movements, and hearing.
Lateral Medullary Syndrome, also known as Wallenberg's syndrome, is a type of stroke that affects the lateral part (side) of the medulla oblongata, which is a structure at the lower end of the brainstem. This condition is typically caused by a blockage or narrowing of the posterior inferior cerebellar artery (PICA), leading to infarction (tissue death due to lack of blood supply) in this area.
The lateral medulla contains several important nerve tracts and nuclei that are responsible for various functions, including:
1. Pain and temperature sensation from the face and body
2. Facial movements and sensations
3. Eye movement control
4. Hearing
5. Vestibular function (balance)
6. Swallowing and cough reflexes
7. Cardiovascular regulation
As a result, individuals with Lateral Medullary Syndrome may experience various symptoms such as:
- Ipsilateral (same side) facial pain and temperature sensation loss
- Contralateral (opposite side) body pain and temperature sensation loss
- Vertigo, dizziness, or unsteady gait due to vestibular dysfunction
- Difficulty swallowing and hoarseness
- Horner's syndrome (drooping eyelid, small pupil, and decreased sweating on the affected side of the face)
- Nystagmus (involuntary eye movement)
- Hiccups
- Ipsilateral (same side) limb ataxia (lack of coordination)
The severity and combination of symptoms may vary depending on the extent and location of the infarction. Treatment typically involves managing underlying risk factors, such as hypertension or diabetes, and providing supportive care to address specific symptoms.
Thermoreceptors are specialized sensory nerve endings or neurons that are sensitive to changes in temperature. They detect and respond to heat or cold stimuli by converting them into electrical signals that are transmitted to the brain for interpretation. These receptors are found throughout the body, particularly in the skin, mucous membranes, and internal organs. There are two main types of thermoreceptors: warm receptors, which respond to increasing temperatures, and cold receptors, which react to decreasing temperatures. The information provided by thermoreceptors helps maintain homeostasis and protect the body from harmful temperature changes.
The foramen magnum is the largest opening in the human skull, located at the base of the skull, through which the spinal cord connects to the brain. It is a crucial structure for the transmission of nerve impulses between the brain and the rest of the body. The foramen magnum also provides passage for blood vessels that supply the brainstem and upper spinal cord.
The kidney medulla is the inner portion of the renal pyramids in the kidney, consisting of multiple conical structures found within the kidney. It is composed of loops of Henle and collecting ducts responsible for concentrating urine by reabsorbing water and producing a hyperosmotic environment. The kidney medulla has a unique blood supply and is divided into an inner and outer zone, with the inner zone having a higher osmolarity than the outer zone. This region of the kidney helps regulate electrolyte and fluid balance in the body.
Prolactin-Releasing Hormone (PRH), also known as Prolactin-Releasing Factor (PRF) or Prolactin-Stimulating Hormone (PSH), is a hypothalamic hormone that stimulates the release of prolactin from the anterior pituitary gland. It is a decapeptide, and its release is regulated by various factors such as stress, estrogen, dopamine, and thyroid-stimulating hormone (TSH). However, it's important to note that the primary regulatory hormone of prolactin secretion is dopamine, which inhibits prolactin release. PRH acts in opposition to dopamine to promote prolactin release.
Despite its identification and characterization, the physiological role of PRH remains unclear, as many studies have suggested that PRH may not be a necessary factor for prolactin secretion under normal conditions. More research is needed to fully understand the function and regulation of this hormone in the body.
In anatomical terms, the reticulum is the second chamber in the ruminant stomach, located between the rumen and the omasum. It is responsible for the continued breakdown of cellulose through microbial fermentation.
However, I believe you may be referring to a term used in pathology or histology. In these contexts, "reticulum" refers to a network of fine fibers, often composed of collagen, that surround cells or organize tissue. It is an important component of the extracellular matrix and provides structural support.
For example, within the liver, the reticulin fibers are part of the hepatic sinusoids' walls and help maintain the liver's architecture. In some disease processes like cirrhosis, these reticulin fibers can become abnormally thickened and contribute to the distortion of the liver's normal structure.
Please let me know if you were looking for information in a different context, and I would be happy to help further!
The spinal cord is a major part of the nervous system, extending from the brainstem and continuing down to the lower back. It is a slender, tubular bundle of nerve fibers (axons) and support cells (glial cells) that carries signals between the brain and the rest of the body. The spinal cord primarily serves as a conduit for motor information, which travels from the brain to the muscles, and sensory information, which travels from the body to the brain. It also contains neurons that can independently process and respond to information within the spinal cord without direct input from the brain.
The spinal cord is protected by the bony vertebral column (spine) and is divided into 31 segments: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal. Each segment corresponds to a specific region of the body and gives rise to pairs of spinal nerves that exit through the intervertebral foramina at each level.
The spinal cord is responsible for several vital functions, including:
1. Reflexes: Simple reflex actions, such as the withdrawal reflex when touching a hot surface, are mediated by the spinal cord without involving the brain.
2. Muscle control: The spinal cord carries motor signals from the brain to the muscles, enabling voluntary movement and muscle tone regulation.
3. Sensory perception: The spinal cord transmits sensory information, such as touch, temperature, pain, and vibration, from the body to the brain for processing and awareness.
4. Autonomic functions: The sympathetic and parasympathetic divisions of the autonomic nervous system originate in the thoracolumbar and sacral regions of the spinal cord, respectively, controlling involuntary physiological responses like heart rate, blood pressure, digestion, and respiration.
Damage to the spinal cord can result in various degrees of paralysis or loss of sensation below the level of injury, depending on the severity and location of the damage.
The brain is the central organ of the nervous system, responsible for receiving and processing sensory information, regulating vital functions, and controlling behavior, movement, and cognition. It is divided into several distinct regions, each with specific functions:
1. Cerebrum: The largest part of the brain, responsible for higher cognitive functions such as thinking, learning, memory, language, and perception. It is divided into two hemispheres, each controlling the opposite side of the body.
2. Cerebellum: Located at the back of the brain, it is responsible for coordinating muscle movements, maintaining balance, and fine-tuning motor skills.
3. Brainstem: Connects the cerebrum and cerebellum to the spinal cord, controlling vital functions such as breathing, heart rate, and blood pressure. It also serves as a relay center for sensory information and motor commands between the brain and the rest of the body.
4. Diencephalon: A region that includes the thalamus (a major sensory relay station) and hypothalamus (regulates hormones, temperature, hunger, thirst, and sleep).
5. Limbic system: A group of structures involved in emotional processing, memory formation, and motivation, including the hippocampus, amygdala, and cingulate gyrus.
The brain is composed of billions of interconnected neurons that communicate through electrical and chemical signals. It is protected by the skull and surrounded by three layers of membranes called meninges, as well as cerebrospinal fluid that provides cushioning and nutrients.
The autonomic nervous system (ANS) is a component of the peripheral nervous system that regulates involuntary physiological functions, such as heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal. The autonomic pathways refer to the neural connections and signaling processes that allow the ANS to carry out these functions.
The autonomic pathways consist of two main subdivisions: the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS). These systems have opposing effects on many organs, with the SNS generally stimulating activity and the PNS inhibiting it. The enteric nervous system, which controls gut function, is sometimes considered a third subdivision of the ANS.
The sympathetic pathway originates in the thoracic and lumbar regions of the spinal cord, with preganglionic neurons synapsing on postganglionic neurons in paravertebral ganglia or prevertebral ganglia. The parasympathetic pathway originates in the brainstem (cranial nerves III, VII, IX, and X) and the sacral region of the spinal cord (S2-S4), with preganglionic neurons synapsing on postganglionic neurons near or within the target organ.
Acetylcholine is the primary neurotransmitter used in both the sympathetic and parasympathetic pathways, although norepinephrine (noradrenaline) is also released by some postganglionic sympathetic neurons. The specific pattern of neural activation and inhibition within the autonomic pathways helps maintain homeostasis and allows for adaptive responses to changes in the internal and external environment.
The solitary nucleus, also known as the nucleus solitarius, is a collection of neurons located in the medulla oblongata region of the brainstem. It plays a crucial role in the processing and integration of sensory information, particularly taste and visceral afferent fibers from internal organs. The solitary nucleus receives inputs from various cranial nerves, including the glossopharyngeal (cranial nerve IX) and vagus nerves (cranial nerve X), and is involved in reflex responses related to swallowing, vomiting, and cardiovascular regulation.
The hypothalamus is a small, vital region of the brain that lies just below the thalamus and forms part of the limbic system. It plays a crucial role in many important functions including:
1. Regulation of body temperature, hunger, thirst, fatigue, sleep, and circadian rhythms.
2. Production and regulation of hormones through its connection with the pituitary gland (the hypophysis). It controls the release of various hormones by producing releasing and inhibiting factors that regulate the anterior pituitary's function.
3. Emotional responses, behavior, and memory formation through its connections with the limbic system structures like the amygdala and hippocampus.
4. Autonomic nervous system regulation, which controls involuntary physiological functions such as heart rate, blood pressure, and digestion.
5. Regulation of the immune system by interacting with the autonomic nervous system.
Damage to the hypothalamus can lead to various disorders like diabetes insipidus, growth hormone deficiency, altered temperature regulation, sleep disturbances, and emotional or behavioral changes.
Medical Definition of Respiration:
Respiration, in physiology, is the process by which an organism takes in oxygen and gives out carbon dioxide. It's also known as breathing. This process is essential for most forms of life because it provides the necessary oxygen for cellular respiration, where the cells convert biochemical energy from nutrients into adenosine triphosphate (ATP), and releases waste products, primarily carbon dioxide.
In humans and other mammals, respiration is a two-stage process:
1. Breathing (or external respiration): This involves the exchange of gases with the environment. Air enters the lungs through the mouth or nose, then passes through the pharynx, larynx, trachea, and bronchi, finally reaching the alveoli where the actual gas exchange occurs. Oxygen from the inhaled air diffuses into the blood, while carbon dioxide, a waste product of metabolism, diffuses from the blood into the alveoli to be exhaled.
2. Cellular respiration (or internal respiration): This is the process by which cells convert glucose and other nutrients into ATP, water, and carbon dioxide in the presence of oxygen. The carbon dioxide produced during this process then diffuses out of the cells and into the bloodstream to be exhaled during breathing.
In summary, respiration is a vital physiological function that enables organisms to obtain the necessary oxygen for cellular metabolism while eliminating waste products like carbon dioxide.
The reticular formation is not a single structure but rather a complex network of interconnected neurons located in the brainstem, extending from the medulla oblongata through the pons and mesencephalon (midbrain) up to the diencephalon (thalamus and hypothalamus). It forms part of the reticular activating system, which is involved in regulating arousal, awareness, and sleep-wake cycles.
The reticular formation plays a crucial role in various functions such as:
1. Modulation of sensory input: The neurons in the reticular formation receive inputs from all senses (visual, auditory, tactile, etc.) and help filter and prioritize this information before it reaches higher cognitive areas.
2. Control of motor function: The reticular formation contributes to the regulation of muscle tone, posture, and locomotion by modulating the activity of motor neurons in the spinal cord.
3. Regulation of autonomic functions: The reticular formation is involved in controlling heart rate, blood pressure, respiration, and other visceral functions through its connections with the autonomic nervous system.
4. Consciousness and arousal: The ascending reticular activating system (ARAS) originates from the reticular formation and projects to the thalamus and cerebral cortex, where it helps maintain wakefulness and arousal. Damage to the ARAS can lead to coma or other states of altered consciousness.
5. Sleep-wake cycle regulation: The reticular formation contains cells that release neurotransmitters like histamine, serotonin, and orexin/hypocretin, which are essential for sleep-wake regulation. Dysfunction in these circuits has been implicated in various sleep disorders, such as narcolepsy and insomnia.
The cerebellum is a part of the brain that lies behind the brainstem and is involved in the regulation of motor movements, balance, and coordination. It contains two hemispheres and a central portion called the vermis. The cerebellum receives input from sensory systems and other areas of the brain and spinal cord and sends output to motor areas of the brain. Damage to the cerebellum can result in problems with movement, balance, and coordination.
Chemoreceptor cells are specialized sensory neurons that detect and respond to chemical changes in the internal or external environment. They play a crucial role in maintaining homeostasis within the body by converting chemical signals into electrical impulses, which are then transmitted to the central nervous system for further processing and response.
There are two main types of chemoreceptor cells:
1. Oxygen Chemoreceptors: These cells are located in the carotid bodies near the bifurcation of the common carotid artery and in the aortic bodies close to the aortic arch. They monitor the levels of oxygen, carbon dioxide, and pH in the blood and respond to decreases in oxygen concentration or increases in carbon dioxide and hydrogen ions (indicating acidity) by increasing their firing rate. This signals the brain to increase respiratory rate and depth, thereby restoring normal oxygen levels.
2. Taste Cells: These chemoreceptor cells are found within the taste buds of the tongue and other areas of the oral cavity. They detect specific tastes (salty, sour, sweet, bitter, and umami) by interacting with molecules from food. When a tastant binds to receptors on the surface of a taste cell, it triggers a series of intracellular signaling events that ultimately lead to the generation of an action potential. This information is then relayed to the brain, where it is interpreted as taste sensation.
In summary, chemoreceptor cells are essential for maintaining physiological balance by detecting and responding to chemical stimuli in the body. They play a critical role in regulating vital functions such as respiration and digestion.
Medical Definition:
Magnetic Resonance Imaging (MRI) is a non-invasive diagnostic imaging technique that uses a strong magnetic field and radio waves to create detailed cross-sectional or three-dimensional images of the internal structures of the body. The patient lies within a large, cylindrical magnet, and the scanner detects changes in the direction of the magnetic field caused by protons in the body. These changes are then converted into detailed images that help medical professionals to diagnose and monitor various medical conditions, such as tumors, injuries, or diseases affecting the brain, spinal cord, heart, blood vessels, joints, and other internal organs. MRI does not use radiation like computed tomography (CT) scans.
The vagus nerve, also known as the 10th cranial nerve (CN X), is the longest of the cranial nerves and extends from the brainstem to the abdomen. It has both sensory and motor functions and plays a crucial role in regulating various bodily functions such as heart rate, digestion, respiratory rate, speech, and sweating, among others.
The vagus nerve is responsible for carrying sensory information from the internal organs to the brain, and it also sends motor signals from the brain to the muscles of the throat and voice box, as well as to the heart, lungs, and digestive tract. The vagus nerve helps regulate the body's involuntary responses, such as controlling heart rate and blood pressure, promoting relaxation, and reducing inflammation.
Dysfunction in the vagus nerve can lead to various medical conditions, including gastroparesis, chronic pain, and autonomic nervous system disorders. Vagus nerve stimulation (VNS) is a therapeutic intervention that involves delivering electrical impulses to the vagus nerve to treat conditions such as epilepsy, depression, and migraine headaches.
"Cat" is a common name that refers to various species of small carnivorous mammals that belong to the family Felidae. The domestic cat, also known as Felis catus or Felis silvestris catus, is a popular pet and companion animal. It is a subspecies of the wildcat, which is found in Europe, Africa, and Asia.
Domestic cats are often kept as pets because of their companionship, playful behavior, and ability to hunt vermin. They are also valued for their ability to provide emotional support and therapy to people. Cats are obligate carnivores, which means that they require a diet that consists mainly of meat to meet their nutritional needs.
Cats are known for their agility, sharp senses, and predatory instincts. They have retractable claws, which they use for hunting and self-defense. Cats also have a keen sense of smell, hearing, and vision, which allow them to detect prey and navigate their environment.
In medical terms, cats can be hosts to various parasites and diseases that can affect humans and other animals. Some common feline diseases include rabies, feline leukemia virus (FeLV), feline immunodeficiency virus (FIV), and toxoplasmosis. It is important for cat owners to keep their pets healthy and up-to-date on vaccinations and preventative treatments to protect both the cats and their human companions.
Sudden Infant Death Syndrome (SIDS) is defined by the American Academy of Pediatrics as "the sudden unexpected death of an infant
A germinoma is a type of tumor that develops in the brain or the spine, primarily in the pituitary gland or pineal gland. It is a rare form of primary central nervous system (CNS) cancer and is classified as a type of germ cell tumor. These tumors arise from cells that normally develop into sperm or eggs, which can migrate to unusual locations during embryonic development.
Germinomas are highly sensitive to radiation therapy and chemotherapy, making them generally treatable and curable with appropriate medical intervention. Symptoms of a germinoma may include headaches, nausea, vomiting, visual disturbances, hormonal imbalances, and neurological deficits, depending on the location and size of the tumor. Diagnosis typically involves imaging studies like MRI or CT scans, followed by a biopsy to confirm the presence of malignant cells.
Neurons, also known as nerve cells or neurocytes, are specialized cells that constitute the basic unit of the nervous system. They are responsible for receiving, processing, and transmitting information and signals within the body. Neurons have three main parts: the dendrites, the cell body (soma), and the axon. The dendrites receive signals from other neurons or sensory receptors, while the axon transmits these signals to other neurons, muscles, or glands. The junction between two neurons is called a synapse, where neurotransmitters are released to transmit the signal across the gap (synaptic cleft) to the next neuron. Neurons vary in size, shape, and structure depending on their function and location within the nervous system.
"Inbred strains of rats" are genetically identical rodents that have been produced through many generations of brother-sister mating. This results in a high degree of homozygosity, where the genes at any particular locus in the genome are identical in all members of the strain.
Inbred strains of rats are widely used in biomedical research because they provide a consistent and reproducible genetic background for studying various biological phenomena, including the effects of drugs, environmental factors, and genetic mutations on health and disease. Additionally, inbred strains can be used to create genetically modified models of human diseases by introducing specific mutations into their genomes.
Some commonly used inbred strains of rats include the Wistar Kyoto (WKY), Sprague-Dawley (SD), and Fischer 344 (F344) rat strains. Each strain has its own unique genetic characteristics, making them suitable for different types of research.
Pressoreceptors are specialized sensory nerve endings found in the walls of blood vessels, particularly in the carotid sinus and aortic arch. They respond to changes in blood pressure by converting the mechanical stimulus into electrical signals that are transmitted to the brain. This information helps regulate cardiovascular function and maintain blood pressure homeostasis.
Scrapie is a progressive, fatal, degenerative disease affecting the central nervous system of sheep and goats. It is one of the transmissible spongiform encephalopathies (TSEs), also known as prion diseases. The agent responsible for scrapie is thought to be an abnormal form of the prion protein, which can cause normal prion proteins in the brain to adopt the abnormal shape and accumulate, leading to brain damage and neurodegeneration.
Scrapie is characterized by several clinical signs, including changes in behavior, tremors, loss of coordination, itching, and excessive scraping of the fleece against hard surfaces, which gives the disease its name. The incubation period for scrapie can range from 2 to 5 years, and there is no known treatment or cure for the disease.
Scrapie is not considered a significant threat to human health, but it has served as a model for understanding other prion diseases, such as bovine spongiform encephalopathy (BSE) in cattle, which can cause variant Creutzfeldt-Jakob disease (vCJD) in humans.
Catecholamines are a group of hormones and neurotransmitters that are derived from the amino acid tyrosine. The most well-known catecholamines are dopamine, norepinephrine (also known as noradrenaline), and epinephrine (also known as adrenaline). These hormones are produced by the adrenal glands and are released into the bloodstream in response to stress. They play important roles in the "fight or flight" response, increasing heart rate, blood pressure, and alertness. In addition to their role as hormones, catecholamines also function as neurotransmitters, transmitting signals in the nervous system. Disorders of catecholamine regulation can lead to a variety of medical conditions, including hypertension, mood disorders, and neurological disorders.
Brain chemistry refers to the chemical processes that occur within the brain, particularly those involving neurotransmitters, neuromodulators, and neuropeptides. These chemicals are responsible for transmitting signals between neurons (nerve cells) in the brain, allowing for various cognitive, emotional, and physical functions.
Neurotransmitters are chemical messengers that transmit signals across the synapse (the tiny gap between two neurons). Examples of neurotransmitters include dopamine, serotonin, norepinephrine, GABA (gamma-aminobutyric acid), and glutamate. Each neurotransmitter has a specific role in brain function, such as regulating mood, motivation, attention, memory, and movement.
Neuromodulators are chemicals that modify the effects of neurotransmitters on neurons. They can enhance or inhibit the transmission of signals between neurons, thereby modulating brain activity. Examples of neuromodulators include acetylcholine, histamine, and substance P.
Neuropeptides are small protein-like molecules that act as neurotransmitters or neuromodulators. They play a role in various physiological functions, such as pain perception, stress response, and reward processing. Examples of neuropeptides include endorphins, enkephalins, and oxytocin.
Abnormalities in brain chemistry can lead to various neurological and psychiatric conditions, such as depression, anxiety disorders, schizophrenia, Parkinson's disease, and Alzheimer's disease. Understanding brain chemistry is crucial for developing effective treatments for these conditions.
Sprague-Dawley rats are a strain of albino laboratory rats that are widely used in scientific research. They were first developed by researchers H.H. Sprague and R.C. Dawley in the early 20th century, and have since become one of the most commonly used rat strains in biomedical research due to their relatively large size, ease of handling, and consistent genetic background.
Sprague-Dawley rats are outbred, which means that they are genetically diverse and do not suffer from the same limitations as inbred strains, which can have reduced fertility and increased susceptibility to certain diseases. They are also characterized by their docile nature and low levels of aggression, making them easier to handle and study than some other rat strains.
These rats are used in a wide variety of research areas, including toxicology, pharmacology, nutrition, cancer, and behavioral studies. Because they are genetically diverse, Sprague-Dawley rats can be used to model a range of human diseases and conditions, making them an important tool in the development of new drugs and therapies.
Proto-oncogene proteins, such as c-Fos, are normal cellular proteins that play crucial roles in various biological processes including cell growth, differentiation, and survival. They can be activated or overexpressed due to genetic alterations, leading to the formation of cancerous cells. The c-Fos protein is a nuclear phosphoprotein involved in signal transduction pathways and forms a heterodimer with c-Jun to create the activator protein-1 (AP-1) transcription factor complex. This complex binds to specific DNA sequences, thereby regulating the expression of target genes that contribute to various cellular responses, including proliferation, differentiation, and apoptosis. Dysregulation of c-Fos can result in uncontrolled cell growth and malignant transformation, contributing to tumor development and progression.
Blood pressure is the force exerted by circulating blood on the walls of the blood vessels. It is measured in millimeters of mercury (mmHg) and is given as two figures:
1. Systolic pressure: This is the pressure when the heart pushes blood out into the arteries.
2. Diastolic pressure: This is the pressure when the heart rests between beats, allowing it to fill with blood.
Normal blood pressure for adults is typically around 120/80 mmHg, although this can vary slightly depending on age, sex, and other factors. High blood pressure (hypertension) is generally considered to be a reading of 130/80 mmHg or higher, while low blood pressure (hypotension) is usually defined as a reading below 90/60 mmHg. It's important to note that blood pressure can fluctuate throughout the day and may be affected by factors such as stress, physical activity, and medication use.
Immunohistochemistry (IHC) is a technique used in pathology and laboratory medicine to identify specific proteins or antigens in tissue sections. It combines the principles of immunology and histology to detect the presence and location of these target molecules within cells and tissues. This technique utilizes antibodies that are specific to the protein or antigen of interest, which are then tagged with a detection system such as a chromogen or fluorophore. The stained tissue sections can be examined under a microscope, allowing for the visualization and analysis of the distribution and expression patterns of the target molecule in the context of the tissue architecture. Immunohistochemistry is widely used in diagnostic pathology to help identify various diseases, including cancer, infectious diseases, and immune-mediated disorders.
A ruptured aneurysm is a serious medical condition that occurs when the wall of an artery or a blood vessel weakens and bulges out, forming an aneurysm, which then bursts, causing bleeding into the surrounding tissue. This can lead to internal hemorrhage, organ damage, and even death, depending on the location and severity of the rupture.
Ruptured aneurysms are often caused by factors such as high blood pressure, smoking, aging, and genetic predisposition. They can occur in any part of the body but are most common in the aorta (the largest artery in the body) and the cerebral arteries (in the brain).
Symptoms of a ruptured aneurysm may include sudden and severe pain, weakness or paralysis, difficulty breathing, confusion, loss of consciousness, and shock. Immediate medical attention is required to prevent further complications and increase the chances of survival. Treatment options for a ruptured aneurysm may include surgery, endovascular repair, or medication to manage symptoms and prevent further bleeding.
Norepinephrine, also known as noradrenaline, is a neurotransmitter and a hormone that is primarily produced in the adrenal glands and is released into the bloodstream in response to stress or physical activity. It plays a crucial role in the "fight-or-flight" response by preparing the body for action through increasing heart rate, blood pressure, respiratory rate, and glucose availability.
As a neurotransmitter, norepinephrine is involved in regulating various functions of the nervous system, including attention, perception, motivation, and arousal. It also plays a role in modulating pain perception and responding to stressful or emotional situations.
In medical settings, norepinephrine is used as a vasopressor medication to treat hypotension (low blood pressure) that can occur during septic shock, anesthesia, or other critical illnesses. It works by constricting blood vessels and increasing heart rate, which helps to improve blood pressure and perfusion of vital organs.
The sympathetic nervous system (SNS) is a part of the autonomic nervous system that operates largely below the level of consciousness, and it functions to produce appropriate physiological responses to perceived danger. It's often associated with the "fight or flight" response. The SNS uses nerve impulses to stimulate target organs, causing them to speed up (e.g., increased heart rate), prepare for action, or otherwise respond to stressful situations.
The sympathetic nervous system is activated due to stressful emotional or physical situations and it prepares the body for immediate actions. It dilates the pupils, increases heart rate and blood pressure, accelerates breathing, and slows down digestion. The primary neurotransmitter involved in this system is norepinephrine (also known as noradrenaline).
The pons is a part of the brainstem that lies between the medulla oblongata and the midbrain. Its name comes from the Latin word "ponte" which means "bridge," as it serves to connect these two regions of the brainstem. The pons contains several important structures, including nerve fibers that carry signals between the cerebellum (the part of the brain responsible for coordinating muscle movements) and the rest of the nervous system. It also contains nuclei (clusters of neurons) that help regulate various functions such as respiration, sleep, and facial movements.
WKY (Wistar Kyoto) is not a term that refers to "rats, inbred" in a medical definition. Instead, it is a strain of laboratory rat that is widely used in biomedical research. WKY rats are an inbred strain, which means they are the result of many generations of brother-sister matings, resulting in a genetically uniform population.
WKY rats originated from the Wistar Institute in Philadelphia and were established as a normotensive control strain to contrast with other rat strains that exhibit hypertension. They have since been used in various research areas, including cardiovascular, neurological, and behavioral studies. Compared to other commonly used rat strains like the spontaneously hypertensive rat (SHR), WKY rats are known for their lower blood pressure, reduced stress response, and greater emotionality.
In summary, "WKY" is a designation for an inbred strain of laboratory rat that is often used as a control group in biomedical research due to its normotensive characteristics.
The Central Nervous System (CNS) is the part of the nervous system that consists of the brain and spinal cord. It is called the "central" system because it receives information from, and sends information to, the rest of the body through peripheral nerves, which make up the Peripheral Nervous System (PNS).
The CNS is responsible for processing sensory information, controlling motor functions, and regulating various autonomic processes like heart rate, respiration, and digestion. The brain, as the command center of the CNS, interprets sensory stimuli, formulates thoughts, and initiates actions. The spinal cord serves as a conduit for nerve impulses traveling to and from the brain and the rest of the body.
The CNS is protected by several structures, including the skull (which houses the brain) and the vertebral column (which surrounds and protects the spinal cord). Despite these protective measures, the CNS remains vulnerable to injury and disease, which can have severe consequences due to its crucial role in controlling essential bodily functions.
Neural pathways, also known as nerve tracts or fasciculi, refer to the highly organized and specialized routes through which nerve impulses travel within the nervous system. These pathways are formed by groups of neurons (nerve cells) that are connected in a series, creating a continuous communication network for electrical signals to transmit information between different regions of the brain, spinal cord, and peripheral nerves.
Neural pathways can be classified into two main types: sensory (afferent) and motor (efferent). Sensory neural pathways carry sensory information from various receptors in the body (such as those for touch, temperature, pain, and vision) to the brain for processing. Motor neural pathways, on the other hand, transmit signals from the brain to the muscles and glands, controlling movements and other effector functions.
The formation of these neural pathways is crucial for normal nervous system function, as it enables efficient communication between different parts of the body and allows for complex behaviors, cognitive processes, and adaptive responses to internal and external stimuli.
Serotonin, also known as 5-hydroxytryptamine (5-HT), is a monoamine neurotransmitter that is found primarily in the gastrointestinal (GI) tract, blood platelets, and the central nervous system (CNS) of humans and other animals. It is produced by the conversion of the amino acid tryptophan to 5-hydroxytryptophan (5-HTP), and then to serotonin.
In the CNS, serotonin plays a role in regulating mood, appetite, sleep, memory, learning, and behavior, among other functions. It also acts as a vasoconstrictor, helping to regulate blood flow and blood pressure. In the GI tract, it is involved in peristalsis, the contraction and relaxation of muscles that moves food through the digestive system.
Serotonin is synthesized and stored in serotonergic neurons, which are nerve cells that use serotonin as their primary neurotransmitter. These neurons are found throughout the brain and spinal cord, and they communicate with other neurons by releasing serotonin into the synapse, the small gap between two neurons.
Abnormal levels of serotonin have been linked to a variety of disorders, including depression, anxiety, schizophrenia, and migraines. Medications that affect serotonin levels, such as selective serotonin reuptake inhibitors (SSRIs), are commonly used to treat these conditions.
"Wistar rats" are a strain of albino rats that are widely used in laboratory research. They were developed at the Wistar Institute in Philadelphia, USA, and were first introduced in 1906. Wistar rats are outbred, which means that they are genetically diverse and do not have a fixed set of genetic characteristics like inbred strains.
Wistar rats are commonly used as animal models in biomedical research because of their size, ease of handling, and relatively low cost. They are used in a wide range of research areas, including toxicology, pharmacology, nutrition, cancer, cardiovascular disease, and behavioral studies. Wistar rats are also used in safety testing of drugs, medical devices, and other products.
Wistar rats are typically larger than many other rat strains, with males weighing between 500-700 grams and females weighing between 250-350 grams. They have a lifespan of approximately 2-3 years. Wistar rats are also known for their docile and friendly nature, making them easy to handle and work with in the laboratory setting.
Carbon dioxide (CO2) is a colorless, odorless gas that is naturally present in the Earth's atmosphere. It is a normal byproduct of cellular respiration in humans, animals, and plants, and is also produced through the combustion of fossil fuels such as coal, oil, and natural gas.
In medical terms, carbon dioxide is often used as a respiratory stimulant and to maintain the pH balance of blood. It is also used during certain medical procedures, such as laparoscopic surgery, to insufflate (inflate) the abdominal cavity and create a working space for the surgeon.
Elevated levels of carbon dioxide in the body can lead to respiratory acidosis, a condition characterized by an increased concentration of carbon dioxide in the blood and a decrease in pH. This can occur in conditions such as chronic obstructive pulmonary disease (COPD), asthma, or other lung diseases that impair breathing and gas exchange. Symptoms of respiratory acidosis may include shortness of breath, confusion, headache, and in severe cases, coma or death.
SHR (Spontaneously Hypertensive Rats) are an inbred strain of rats that were originally developed through selective breeding for high blood pressure. They are widely used as a model to study hypertension and related cardiovascular diseases, as well as neurological disorders such as stroke and dementia.
Inbred strains of animals are created by mating genetically identical individuals (siblings or offspring) for many generations, resulting in a population that is highly homozygous at all genetic loci. This means that the animals within an inbred strain are essentially genetically identical to one another, which makes them useful for studying the effects of specific genes or environmental factors on disease processes.
SHR rats develop high blood pressure spontaneously, without any experimental manipulation, and show many features of human hypertension, such as increased vascular resistance, left ventricular hypertrophy, and renal dysfunction. They also exhibit a number of behavioral abnormalities, including hyperactivity, impulsivity, and cognitive deficits, which make them useful for studying the neurological consequences of hypertension and other cardiovascular diseases.
Overall, inbred SHR rats are an important tool in biomedical research, providing a valuable model for understanding the genetic and environmental factors that contribute to hypertension and related disorders.
Heart rate is the number of heartbeats per unit of time, often expressed as beats per minute (bpm). It can vary significantly depending on factors such as age, physical fitness, emotions, and overall health status. A resting heart rate between 60-100 bpm is generally considered normal for adults, but athletes and individuals with high levels of physical fitness may have a resting heart rate below 60 bpm due to their enhanced cardiovascular efficiency. Monitoring heart rate can provide valuable insights into an individual's health status, exercise intensity, and response to various treatments or interventions.
I apologize, but "sheep" is not a term that has a medical definition. It is a common animal with the scientific name Ovis aries. If you have any medical or health-related questions, I would be happy to try and help answer those for you.
Brain neoplasms, also known as brain tumors, are abnormal growths of cells within the brain. These growths can be benign (non-cancerous) or malignant (cancerous). Benign brain tumors typically grow slowly and do not spread to other parts of the body. However, they can still cause serious problems if they press on sensitive areas of the brain. Malignant brain tumors, on the other hand, are cancerous and can grow quickly, invading surrounding brain tissue and spreading to other parts of the brain or spinal cord.
Brain neoplasms can arise from various types of cells within the brain, including glial cells (which provide support and insulation for nerve cells), neurons (nerve cells that transmit signals in the brain), and meninges (the membranes that cover the brain and spinal cord). They can also result from the spread of cancer cells from other parts of the body, known as metastatic brain tumors.
Symptoms of brain neoplasms may vary depending on their size, location, and growth rate. Common symptoms include headaches, seizures, weakness or paralysis in the limbs, difficulty with balance and coordination, changes in speech or vision, confusion, memory loss, and changes in behavior or personality.
Treatment for brain neoplasms depends on several factors, including the type, size, location, and grade of the tumor, as well as the patient's age and overall health. Treatment options may include surgery, radiation therapy, chemotherapy, targeted therapy, or a combination of these approaches. Regular follow-up care is essential to monitor for recurrence and manage any long-term effects of treatment.
Tissue distribution, in the context of pharmacology and toxicology, refers to the way that a drug or xenobiotic (a chemical substance found within an organism that is not naturally produced by or expected to be present within that organism) is distributed throughout the body's tissues after administration. It describes how much of the drug or xenobiotic can be found in various tissues and organs, and is influenced by factors such as blood flow, lipid solubility, protein binding, and the permeability of cell membranes. Understanding tissue distribution is important for predicting the potential effects of a drug or toxin on different parts of the body, and for designing drugs with improved safety and efficacy profiles.
Messenger RNA (mRNA) is a type of RNA (ribonucleic acid) that carries genetic information copied from DNA in the form of a series of three-base code "words," each of which specifies a particular amino acid. This information is used by the cell's machinery to construct proteins, a process known as translation. After being transcribed from DNA, mRNA travels out of the nucleus to the ribosomes in the cytoplasm where protein synthesis occurs. Once the protein has been synthesized, the mRNA may be degraded and recycled. Post-transcriptional modifications can also occur to mRNA, such as alternative splicing and addition of a 5' cap and a poly(A) tail, which can affect its stability, localization, and translation efficiency.
In the field of medicine, "time factors" refer to the duration of symptoms or time elapsed since the onset of a medical condition, which can have significant implications for diagnosis and treatment. Understanding time factors is crucial in determining the progression of a disease, evaluating the effectiveness of treatments, and making critical decisions regarding patient care.
For example, in stroke management, "time is brain," meaning that rapid intervention within a specific time frame (usually within 4.5 hours) is essential to administering tissue plasminogen activator (tPA), a clot-busting drug that can minimize brain damage and improve patient outcomes. Similarly, in trauma care, the "golden hour" concept emphasizes the importance of providing definitive care within the first 60 minutes after injury to increase survival rates and reduce morbidity.
Time factors also play a role in monitoring the progression of chronic conditions like diabetes or heart disease, where regular follow-ups and assessments help determine appropriate treatment adjustments and prevent complications. In infectious diseases, time factors are crucial for initiating antibiotic therapy and identifying potential outbreaks to control their spread.
Overall, "time factors" encompass the significance of recognizing and acting promptly in various medical scenarios to optimize patient outcomes and provide effective care.
I believe there may be some confusion in your question. "Fires" is not a medical term that I am aware of. In a general context, a fire refers to the rapid oxidation of a material in the chemical process of combustion, releasing heat, light, and various reaction products. If you are asking about a specific medical term or condition, could you please provide more context or clarify your question? I'm here to help!
I'm sorry for any confusion, but "Fire Extinguishing Systems" is not a term typically used in medical definitions. It is more related to fire safety and building codes.
However, I can provide you with a general definition:
Fire extinguishing systems are engineering solutions designed to suppress or control fires in a given area. They are installed in buildings and other facilities to protect life and property. These systems can use various types of extinguishing agents, such as water, foam, dry chemicals, clean agents, or carbon dioxide, depending on the specific fire hazards present. Examples of fire extinguishing systems include automatic sprinkler systems, clean agent fire suppression systems, and portable fire extinguishers.
'Hypericum' is a genus of flowering plants, also known as St. John's Wort. While it is primarily used in herbal medicine and not considered a standard medical term, it is important to note that some species of Hypericum have been found to have medicinal properties. The most commonly studied and used species is Hypericum perforatum, which has been found to have potential benefits in treating depression, anxiety, and sleep disorders. However, its use as a medical treatment is still a subject of ongoing research and debate, and it can interact with several medications. Always consult with a healthcare provider before starting any new supplement or medication.
I believe there may be some confusion in your question. "Firefighters" are not a medical term, but rather a professional title for those who extinguish fires and prevent fire-related hazards. They are emergency responders who play a crucial role in public safety. If you're asking about any medical conditions or health aspects related to firefighting, I would be happy to help with that.
"Beetles" is not a medical term. It is a common name used to refer to insects belonging to the order Coleoptera, which is one of the largest orders in the class Insecta. Beetles are characterized by their hardened forewings, known as elytra, which protect their hind wings and body when not in use for flying.
There are many different species of beetles found all over the world, and some can have an impact on human health. For example, certain types of beetles, such as bed bugs and carpet beetles, can cause skin irritation and allergic reactions in some people. Other beetles, like the Colorado potato beetle, can damage crops and lead to economic losses for farmers. However, it is important to note that most beetles are not harmful to humans and play an essential role in ecosystems as decomposers and pollinators.
Fossil fuels are not a medical term, but rather a term used in the field of earth science and energy production. They refer to fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes even hundreds of millions of years.
There are three main types of fossil fuels: coal, petroleum, and natural gas. Coal is primarily composed of carbon and hydrogen, and it is formed from the remains of plants that lived hundreds of millions of years ago in swamps and peat bogs. Petroleum, also known as crude oil, is a liquid mixture of hydrocarbons and other organic compounds, formed from the remains of marine organisms such as algae and zooplankton. Natural gas is primarily composed of methane and other light hydrocarbons, and it is found in underground reservoirs, often in association with petroleum deposits.
Fossil fuels are a major source of energy for transportation, heating, and electricity generation, but their combustion also releases large amounts of carbon dioxide and other pollutants into the atmosphere, contributing to climate change and air pollution.
'Erwinia amylovora' is a species of gram-negative, facultatively anaerobic bacteria that is a plant pathogen and the causative agent of fire blight, a destructive disease affecting members of the Rosaceae family, including apple and pear trees. The bacteria are capable of producing various virulence factors, such as cell wall-degrading enzymes and toxins, which contribute to their ability to cause disease in plants.
The bacteria typically enter the plant through wounds or natural openings, such as flowers, and then spread through the vascular system, causing wilting, discoloration, and death of infected tissues. In severe cases, fire blight can lead to the death of entire trees or orchards. The disease is difficult to control once it becomes established in an area, and management strategies typically involve a combination of cultural practices, such as pruning and sanitation, and the use of protective chemicals.
In addition to its economic impact on agriculture, 'Erwinia amylovora' has also been studied as a model organism for understanding plant-pathogen interactions and the mechanisms of bacterial pathogenesis.
Medulla oblongata
Medulla Oblongata (film)
Posterolateral sulcus of medulla oblongata
Posterior median sulcus of medulla oblongata
Anterior median fissure of the medulla oblongata
Parafacial zone
Medial medullary syndrome
Medullary pyramids (brainstem)
Nucleus raphe obscurus
Medial vestibular nucleus
Intercalated nucleus
Glossopharyngeal nerve
Human brain
Posterior inferior cerebellar artery
Subarachnoid cisterns
Circumventricular organs
Bulbar palsy
Posterior cranial fossa
Babinski-Nageotte syndrome
Pallesthesia
Differential diagnoses of anorexia nervosa
Ventral reticular nucleus
Hindbrain
Trigger zone
HCN1
Brain tumor
Peristalsis
Dorsal column nuclei
Mansour Ali Haseeb
Vasomotor center
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Pons11
- The brainstem is divided into the medulla, pons, and midbrain. (medscape.com)
- The brainstem is comprised of three main parts: the midbrain, the pons, and the medulla oblongata. (proprofs.com)
- It consists of three parts: the midbrain, pons, and medulla oblongata. (proprofs.com)
- The midbrain gives rise to two pairs, the pons gives rise to four pairs, and the medulla oblongata gives rise to four pairs. (proprofs.com)
- The brain stem has 3 main parts: the midbrain, pons, and medulla oblongata. (cancer.org)
- Three major regions make up the brain stem: medulla oblongata, pons, and midbrain. (innerbody.com)
- Superior to the medulla is the pons, which is larger and structurally more complex than the medulla. (innerbody.com)
- Like the medulla, the pons plays a vital role in communication as it contains all of the neurons that connect the higher regions of the brain to the medulla and spinal cord. (innerbody.com)
- Like the pons and medulla, all of the neurons descending to the lower brain stem, cerebellum and spinal cord and ascending to the diencephalon and cerebrum pass through the midbrain. (innerbody.com)
- and the brain stem contains the midbrain, pons, and medulla oblongata. (cdc.gov)
- The midbrain controls movement, vision, and hearing, while the pons manages communication between different parts of the brain and the medulla oblongata controls involuntary processes like breathing and digestion. (nhnscr.org)
Brainstem6
- The medulla oblongata or simply medulla is a long stem-like structure which makes up the lower part of the brainstem. (wikipedia.org)
- The proportion, quantity or volume in the medulla oblongata (the region of the brainstem that lies directly above the spinal cord and controls vital autonomic functions) of a monoamine neurotransmitter derived primarily from tryptophan. (mcw.edu)
- Medulla oblongata is the lower part of the brainstem (lower end of the brain that continues downwards as the spinal cord). (anatomic.us)
- An abnormality of the medulla oblongata, the lower half of the brainstem. (beds.ac.uk)
- The medulla oblongata, located on the lower part of the brainstem near the other more primitive brain structures responsible for fight or flight, is the part in charge of the involuntary functions of your body, including your heart rate, and the rate of your breathing, and vomiting. (calmclinic.com)
- Encephalitic necrotic lesions were multifocal but predominant in the inferior brainstem and superior cervical medulla. (cdc.gov)
Spinal cord6
- The posterior part of the medulla between the posterior median sulcus and the posterolateral sulcus contains tracts that enter it from the posterior funiculus of the spinal cord. (wikipedia.org)
- With the use of an en bloc in vitro preparation of mouse spinal cord (2-3 d old), which either was isolated completely or had muscles of the hindlimb left intact, we show that the bath application of AVP or OXT can evoke an increase in population bursting of motoneurons recorded from the lumbar ventral roots. (jneurosci.org)
- The medulla is the inferior-most region of the brain stem that connects the brain to the spinal cord. (innerbody.com)
- The medulla contains all of the neurons that connect the brain to the spinal cord, and it is at the level of the medulla that about 90% of these neurons switch from the left side of the body to the right and vice versa. (innerbody.com)
- The apricot was the sniper's nickname for the medulla oblongata, the cone-shaped mass of neurons that connected the brain to the spinal cord. (wiktionary.org)
- Demyelination in the brain (medulla oblongata) and spinal cord was observed in male and female rats in the 13-week study. (nih.gov)
Neurons3
- The soma (cell bodies) in these nuclei are the second-order neurons of the posterior column-medial lemniscus pathway, and their axons, called the internal arcuate fibers or fasciculi, decussate from one side of the medulla to the other to form the medial lemniscus. (wikipedia.org)
- Participation of reticular neurons of the cat medulla oblongata in the integration of the respiration center activity]. (consensus.app)
- These neurons passing through the medulla also form many relays, where one neuron passes its signal on to another neuron that continues onward to the brain or body. (innerbody.com)
Adrenal medulla3
- Your sympathetic nerves alert the adrenal medulla to release that famous hormone that goes by the name of adrenaline into the body, along with a small amount of dopamine, making the body initially feel better than it otherwise would (which is known in combination as the adrenaline rush). (calmclinic.com)
- Browse 3,700+ medulla stock photos and images available, or search for adrenal medulla or medulla oblongata to find more great stock photos and pictures. (istockphoto.com)
- 13. Fos-related antigen 2: potential mediator of the transcriptional activation in rat adrenal medulla evoked by repeated immobilization stress. (nih.gov)
Cerebellum1
- The fossa is bounded on either side by the inferior cerebellar peduncle, which connects the medulla to the cerebellum. (wikipedia.org)
Nuclei1
- Nuclei of gray matter in the medulla include the cardiovascular center, which controls the heart rate and blood pressure, and the medullary rhythmicity area, which controls the breathing rate. (innerbody.com)
Hindbrain1
- The Medulla Oblongata is a subsection of the hindbrain. (boom-online.co.uk)
Posterior3
- Just above the tubercles, the posterior aspect of the medulla is occupied by a triangular fossa, which forms the lower part of the floor of the fourth ventricle. (wikipedia.org)
- Posterior inferior cerebellar artery: This is a major branch of the vertebral artery, and supplies the posterolateral part of the medulla, where the main sensory tracts run and synapse. (wikipedia.org)
- Posterior spinal artery: This supplies the dorsal column of the closed medulla containing fasciculus gracilis, gracile nucleus, fasciculus cuneatus, and cuneate nucleus. (wikipedia.org)
Nerves2
- The word bulbar can refer to the nerves and tracts connected to the medulla, and also by association to those muscles innervated, such as those of the tongue, pharynx and larynx. (wikipedia.org)
- The word " bulbar " is also used in medical clinics for the nerves and associated structures of medulla. (anatomic.us)
Neurological1
- Jupiter controls the medulla oblongata, the neurological center of the brain, and the three rings of the brain stem. (3ho.org)
Bulbar1
- In modern clinical usage, the word bulbar (as in bulbar palsy) is retained for terms that relate to the medulla oblongata, particularly in reference to medical conditions. (wikipedia.org)
Centers2
- The medulla contains the cardiac, respiratory, vomiting and vasomotor centers, and therefore deals with the autonomic functions of breathing, heart rate and blood pressure as well as the sleep-wake cycle. (wikipedia.org)
- Respiratory centers were affected, as were vegetative nucleates of the medulla oblongata ( Figure 1 ). (cdc.gov)
Inferior1
- a lower closed part or inferior part where the fourth ventricle has narrowed at the obex in the caudal medulla, and surrounds part of the central canal. (wikipedia.org)
Cardiac1
- Once tagged by the parabrachial nucleus, the medulla oblongata starts sending word to the lungs and cardiac muscles that extra air is needed for circulation to the muscles of the body by way of the blood. (calmclinic.com)
Breath2
- When the body doesn't actually need to fight or flee, the quick breathing and extra air that the medulla oblongata has sent for overwhelms the body and results in both dyspnea, or shortness of breath, and hyperventilation. (calmclinic.com)
- The mantra Hong-Sau has a vibratory connection with the breath through its resonance in the medulla oblongata, which controls the breath (as well as the pulse rate and the blood pressure). (spiritualityhealth.com)
Artery1
- Anterior spinal artery: This supplies the whole medial part of the medulla oblongata. (wikipedia.org)
Superior1
- The medulla can be thought of as being in two parts: an upper open part or superior part where the dorsal surface of the medulla is formed by the fourth ventricle. (wikipedia.org)
Lower1
- The lower part of the medulla, immediately lateral to the cuneate fasciculus, is marked by another longitudinal elevation known as the tuberculum cinereum. (wikipedia.org)
Region1
- The region between the anterolateral and posterolateral sulcus in the upper part of the medulla is marked by a pair of swellings known as olivary bodies (also called olives). (wikipedia.org)
Forms1
- The medulla oblongata forms in fetal development from the myelencephalon. (wikipedia.org)
Blood2
- Blood to the medulla is supplied by a number of arteries. (wikipedia.org)
- The nucleus ambiguus, located just below the medulla oblongata, is the part that receives its urgent call for more blood to transport extra oxygen. (calmclinic.com)
Thought3
- Nigeness: 'I know he thought a lotta My Medulla Oblongata. (blogspot.com)
- I know he thought a lotta My Medulla Oblongata. (blogspot.com)
- It is thought that psychopathy is caused by a misfiring in the brain so the unconditioned fear stimulus in the medulla oblongata does not work in some people as it does in what we call "normal" people. (boyfrombrazil.co.uk)
Term1
- The bulb is an archaic term for the medulla oblongata. (wikipedia.org)
Seat1
- The medulla oblongata is the seat of ego-consciousness. (spiritualityhealth.com)
Structure1
- The amygdala starts by communicating with the parabrachial nucleus, a structure looking something like a small gray horseshoe, which, in turn, triggers the medulla oblongata. (calmclinic.com)
Upper1
- Typical localization: focal: upper cervical cord and medulla oblongata (12). (cdc.gov)