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Glomus Type I Cell
Glomus cells are the cell type mainly located in the carotid bodies and aortic bodies. Glomus type I cells are peripheral chemoreceptors which sense the oxygen, carbon dioxide and pH levels of the blood. When there is a decrease in the blood's pH, a decrease in oxygen (pO2), or an increase in carbon dioxide ( pCO2), the carotid bodies and the aortic bodies signal the dorsal respiratory group in the medulla oblongata to increase the volume and rate of breathing. The glomus cells have a high metabolic rate and good blood perfusion and thus are sensitive to changes in arterial blood gas tension. Glomus type II cells are sustentacular cells having a similar supportive function to glial cells. Structure The signalling within the chemoreceptors is thought to be mediated by the release of neurotransmitters by the glomus cells, including dopamine, noradrenaline, acetylcholine, substance P, vasoactive intestinal peptide and enkephalins. Vasopressin has been found to inhibit the res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glomus Body
:''The glomus body is not to be confused with the glomus cell which is a kind of chemoreceptor found in the carotid body, carotid bodies and aortic body, aortic bodies.'' A glomus body (or glomus organ) is a component of the dermis layer of the skin, involved in thermoregulation , body temperature regulation. The glomus body is a small arteriovenous anastomosis surrounded by a capsule of connective tissue. Glomus bodies (glomera) are most numerous in the fingers and toes. The role of the glomus body is to shunt blood away (heat transfer) from the skin surface when exposed to cold temperature, thus preventing heat loss, and allowing maximum blood flow to the skin in warm weather to allow heat to dissipate. The glomus body has high sympathetic tone and potentiation leads to near complete vasoconstriction. Endothelial cells form a single, continuous layer that lines all vascular segments. Junctional complexes keep the endothelial cells together in arteries but are less numerous in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enkephalin
An enkephalin is a pentapeptide involved in regulating nociception in the body. The enkephalins are termed endogenous ligands, as they are internally derived and bind to the body's opioid receptors. Discovered in 1975, two forms of enkephalin have been found, one containing leucine ("leu"), and the other containing methionine ("met"). Both are products of the proenkephalin gene. * Met-enkephalin is Tyr-Gly-Gly-Phe-Met. * Leu-enkephalin has Tyr-Gly-Gly-Phe-Leu. Endogenous opioid peptides There are three well-characterized families of opioid peptides produced by the body: enkephalins, B-endorphin, and dynorphins. The met-enkephalin peptide sequence is coded for by the enkephalin gene; the leu-enkephalin peptide sequence is coded for by both the enkephalin gene and the dynorphin gene. The proopiomelanocortin gene (POMC) also contains the met-enkephalin sequence on the N-terminus of beta-endorphin, but the endorphin peptide is not processed into enkephalin. Effects on stress ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adenosine
Adenosine ( symbol A) is an organic compound that occurs widely in nature in the form of diverse derivatives. The molecule consists of an adenine attached to a ribose via a β-N9-glycosidic bond. Adenosine is one of the four nucleoside building blocks of RNA (and its derivative deoxyadenosine is a building block of DNA), which are essential for all life. Its derivatives include the energy carriers adenosine mono-, di-, and triphosphate, also known as AMP/ADP/ATP. Cyclic adenosine monophosphate (cAMP) is pervasive in signal transduction. Adenosine is used as an intravenous medication for some cardiac arrhythmias. Adenosyl (abbreviated Ado or 5'-dAdo) is the chemical group formed by removal of the 5′-hydroxy (OH) group. It is found in adenosylcobalamin (an active form of vitamin B12) and as a radical in radical SAM enzymes. Medical uses Supraventricular tachycardia In individuals with supraventricular tachycardia (SVT), adenosine is used to help identify and convert the rhyt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carotid Sinus Nerve
The carotid branch of the glossopharyngeal nerve (carotid sinus nerve or Hering's nerve) is a small branch of the glossopharyngeal nerve that innervates the carotid sinus and carotid body. It is a branch of the glossopharyngeal nerve that runs downwards, anterior to the internal carotid artery. It communicates with the vagus nerve and sympathetic trunk and then divides in the angle of the bifurcation of the common carotid artery to innervate the carotid body and carotid sinus. It carries impulses from the baroreceptors in the carotid sinus to the vasomotor center in the brainstem (to help maintain a more consistent blood pressure) and from chemoreceptors in the carotid body The carotid body is a small cluster of chemoreceptor cells, and supporting sustentacular cells. The carotid body is located in the adventitia, in the bifurcation (fork) of the common carotid artery, which runs along both sides of the neck. The ... (mainly monitoring blood gas PaO2 and PaCO2 levels). Refere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Afferent Nerve Fiber
Afferent nerve fibers are the axons (nerve fibers) carried by a sensory nerve that relay sensory information from sensory receptors to regions of the brain. Afferent projections ''arrive'' at a particular brain region. Efferent nerve fibers are carried by efferent nerves and ''exit'' a region to act on muscles and glands. In the peripheral nervous system afferent and efferent nerve fibers are part of the somatic nervous system and arise from outside of the spinal cord. Sensory nerves carry the afferent fibers to enter into the spinal cord, and motor nerves carry the efferent fibers out of the spinal cord to act on skeletal muscles. In the central nervous system non-motor efferents are carried in efferent nerves to act on glands. Structure Afferent neurons are pseudounipolar neurons that have a single process leaving the cell body dividing into two branches: the long one towards the sensory organ, and the short one toward the central nervous system (e.g. spinal cord). The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acidosis
Acidosis is a process causing increased acidity in the blood and other body tissues (i.e., an increase in hydrogen ion concentration). If not further qualified, it usually refers to acidity of the blood plasma. The term ''acidemia'' describes the state of low blood pH, while ''acidosis'' is used to describe the processes leading to these states. Nevertheless, the terms are sometimes used interchangeably. The distinction may be relevant where a patient has factors causing both acidosis and alkalosis, wherein the relative severity of both determines whether the result is a high, low, or normal pH. Acidemia is said to occur when arterial pH falls below 7.35 (except in the fetus – see below), while its counterpart ( alkalemia) occurs at a pH over 7.45. Arterial blood gas analysis and other tests are required to separate the main causes. The rate of cellular metabolic activity affects and, at the same time, is affected by the pH of the body fluids. In mammals, the normal pH of ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypercapnia
Hypercapnia (from the Greek ''hyper'' = "above" or "too much" and ''kapnos'' = "smoke"), also known as hypercarbia and CO2 retention, is a condition of abnormally elevated carbon dioxide (CO2) levels in the blood. Carbon dioxide is a gaseous product of the body's metabolism and is normally expelled through the lungs. Carbon dioxide may accumulate in any condition that causes hypoventilation, a reduction of alveolar ventilation (the clearance of air from the small sacs of the lung where gas exchange takes place) as well as resulting from inhalation of CO2. Inability of the lungs to clear carbon dioxide, or inhalation of elevated levels of CO2, leads to respiratory acidosis. Eventually the body compensates for the raised acidity by retaining alkali in the kidneys, a process known as "metabolic compensation". Acute hypercapnia is called acute hypercapnic respiratory failure (AHRF) and is a medical emergency as it generally occurs in the context of acute illness. Chronic hypercapnia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypoxemia
Hypoxemia is an abnormally low level of oxygen in the blood. More specifically, it is oxygen deficiency in arterial blood. Hypoxemia has many causes, and often causes hypoxia as the blood is not supplying enough oxygen to the tissues of the body. Definition ''Hypoxemia'' refers to the low level of oxygen in blood, and the more general term ''hypoxia'' is an abnormally low oxygen content in any tissue or organ, or the body as a whole. Hypoxemia can cause hypoxia (hypoxemic hypoxia), but hypoxia can also occur via other mechanisms, such as anemia. Hypoxemia is usually defined in terms of reduced partial pressure of oxygen (mm Hg) in arterial blood, but also in terms of reduced content of oxygen (ml oxygen per dl blood) or percentage saturation of hemoglobin (the oxygen-binding protein within red blood cells) with oxygen, which is either found singly or in combination. While there is general agreement that an arterial blood gas measurement which shows that the partial pressure of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sensory Neuron
Sensory neurons, also known as afferent neurons, are neurons in the nervous system, that convert a specific type of stimulus, via their receptors, into action potentials or graded potentials. This process is called sensory transduction. The cell bodies of the sensory neurons are located in the dorsal ganglia of the spinal cord. The sensory information travels on the afferent nerve fibers in a sensory nerve, to the brain via the spinal cord. The stimulus can come from ''exteroreceptors'' outside the body, for example those that detect light and sound, or from ''interoreceptors'' inside the body, for example those that are responsive to blood pressure or the sense of body position. Types and function Different types of sensory neurons have different sensory receptors that respond to different kinds of stimuli. There are at least six external and two internal sensory receptors: External receptors External receptors that respond to stimuli from outside the body are called ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AT1 Receptor
Angiotensin II receptor type 1 (AT1) is the best characterized angiotensin receptor. It is encoded in humans by the ''AGTR1'' gene. AT1 has vasopressor effects and regulates aldosterone secretion. It is an important effector controlling blood pressure and volume in the cardiovascular system. Angiotensin II receptor blockers are drugs indicated for hypertension, diabetic nephropathy and congestive heart failure. Function The AT1 receptor mediates the major cardiovascular effects of angiotensin II. Effects include vasoconstriction, aldosterone synthesis and secretion, increased vasopressin secretion, cardiac hypertrophy, augmentation of peripheral noradrenergic activity, vascular smooth muscle cells proliferation, decreased renal blood flow, renal renin inhibition, renal tubular sodium reuptake, modulation of central sympathetic nervous system activity, cardiac contractility, central osmocontrol and extracellular matrix formation. The main function of angiotensin II in the bra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angiotensin II
Angiotensin is a peptide hormone that causes vasoconstriction and an increase in blood pressure. It is part of the renin–angiotensin system, which regulates blood pressure. Angiotensin also stimulates the release of aldosterone from the adrenal cortex to promote sodium retention by the kidneys. An oligopeptide, angiotensin is a hormone and a dipsogen. It is derived from the precursor molecule angiotensinogen, a serum globulin produced in the liver. Angiotensin was isolated in the late 1930s (first named 'angiotonin' or 'hypertensin') and subsequently characterized and synthesized by groups at the Cleveland Clinic and Ciba laboratories. Precursor and types Angiotensinogen Angiotensinogen is an α-2-globulin synthesized in the liver and is a precursor for angiotensin, but has also been indicated as having many other roles not related to angiotensin peptides. It is a member of the serpin family of proteins, leading to another name: Serpin A8, although it is not known ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypovolemia
Hypovolemia, also known as volume depletion or volume contraction, is a state of abnormally low extracellular fluid in the body. This may be due to either a loss of both salt and water or a decrease in blood volume. Hypovolemia refers to the loss of extracellular fluid and should not be confused with dehydration. Hypovolemia is caused by a variety of events, but these can be simplified into two categories: those that are associated with kidney function and those that are not. The signs and symptoms of hypovolemia worsen as the amount of fluid lost increases. Immediately or shortly after mild fluid loss (from blood donation, diarrhea, vomiting, bleeding from trauma, etc.), one may experience headache, fatigue, weakness, dizziness, or thirst. Untreated hypovolemia or excessive and rapid losses of volume may lead to hypovolemic shock. Signs and symptoms of hypovolemic shock include increased heart rate, low blood pressure, pale or cold skin, and altered mental status. When these ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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