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Hyperemia
Hyperaemia (also hyperemia) is the increase of blood flow to different tissues in the body. It can have medical implications but is also a regulatory response, allowing change in blood supply to different tissues through vasodilation. Clinically, hyperaemia in tissues manifests as erythema (redness of the skin) because of the engorgement of vessels with oxygenated blood. Hyperaemia can also occur due to a fall in atmospheric pressure outside the body. The term is from Greek ὑπέρ (''hupér'') 'over' + αἷμα (''haîma'') 'blood'. Regulation of blood flow Functional hyperaemia is an increase in blood flow to a tissue due to the presence of metabolites and a change in general conditions. When a tissue increases activity there is a well-characterized fall in the partial pressure of oxygen and pH, an increase in partial pressure of carbon dioxide, and a rise in temperature and the concentration of potassium ions. The mechanisms of vasodilation are predominantly local metabolit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erythema
Erythema (from the Greek , meaning red) is redness of the skin or mucous membranes, caused by hyperemia (increased blood flow) in superficial capillaries. It occurs with any skin injury, infection, or inflammation. Examples of erythema not associated with pathology include nervous blushes. Types * Erythema ab igne * Erythema chronicum migrans * Erythema induratum * Erythema infectiosum (or fifth disease) * Erythema marginatum * Erythema migrans * Erythema multiforme (EM) * Erythema nodosum * Erythema toxicum * Erythema elevatum diutinum * Erythema gyratum repens * Keratolytic winter erythema * Palmar erythema Causes It can be caused by infection, massage, electrical treatment, acne medication, allergies, exercise, solar radiation (sunburn), photosensitization, acute radiation syndrome, mercury toxicity, blister agents, niacin administration, or waxing and tweezing of the hairs—any of which can cause the capillaries to dilate, resulting in redness. Erythema is a common sid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erythema
Erythema (from the Greek , meaning red) is redness of the skin or mucous membranes, caused by hyperemia (increased blood flow) in superficial capillaries. It occurs with any skin injury, infection, or inflammation. Examples of erythema not associated with pathology include nervous blushes. Types * Erythema ab igne * Erythema chronicum migrans * Erythema induratum * Erythema infectiosum (or fifth disease) * Erythema marginatum * Erythema migrans * Erythema multiforme (EM) * Erythema nodosum * Erythema toxicum * Erythema elevatum diutinum * Erythema gyratum repens * Keratolytic winter erythema * Palmar erythema Causes It can be caused by infection, massage, electrical treatment, acne medication, allergies, exercise, solar radiation (sunburn), photosensitization, acute radiation syndrome, mercury toxicity, blister agents, niacin administration, or waxing and tweezing of the hairs—any of which can cause the capillaries to dilate, resulting in redness. Erythema is a common sid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neuron
A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. Non-animals like plants and fungi do not have nerve cells. Neurons are typically classified into three types based on their function. Sensory neurons respond to stimuli such as touch, sound, or light that affect the cells of the sensory organs, and they send signals to the spinal cord or brain. Motor neurons receive signals from the brain and spinal cord to control everything from muscle contractions to glandular output. Interneurons connect neurons to other neurons within the same region of the brain or spinal cord. When multiple neurons are connected together, they form what is called a neural circuit. A typical neuron consists of a cell body (soma), dendrites, and a single axon. The soma is a compact structure, and the axon and dend ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vasospasm
Vasospasm refers to a condition in which an arterial spasm leads to vasoconstriction. This can lead to tissue ischemia and tissue death (necrosis). Cerebral vasospasm may arise in the context of subarachnoid hemorrhage. Symptomatic vasospasm or delayed cerebral ischemia is a major contributor to post-operative stroke and death especially after aneurysmal subarachnoid hemorrhage. Vasospasm typically appears 4 to 10 days after subarachnoid hemorrhage. Along with physical resistance, vasospasm is a main cause of ischemia. Like physical resistance, vasospasms can occur due to atherosclerosis. Vasospasm is the major cause of Prinzmetal's angina. Pathophysiology Normally endothelial cells release prostacyclin and nitric oxide (NO) which induce relaxation of the smooth muscle cells, and reduce aggregation of platelets. Aggregating platelets stimulate ADP to act on endothelial cells and help them induce relaxation of the smooth muscle cells. However, aggregating platelets also stimulat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Raynaud's Phenomenon
Raynaud syndrome, also known as Raynaud's phenomenon, eponymously named after the physician Auguste Gabriel Maurice Raynaud, who first described it in his doctoral thesis in 1862, is a medical condition in which the spasm of small arteries causes episodes of reduced blood flow to end arterioles. Typically, the fingers, and less commonly, the toes, are involved. Rarely, the nose, ears, or lips are affected. The episodes classically result in the affected part turning white and then blue. Often, numbness or pain occurs. As blood flow returns, the area turns red and burns. The episodes typically last minutes but can last several hours. Episodes are typically triggered by cold or emotional stress. Primary Raynaud's, also known as idiopathic, means that it is spontaneous, of unknown cause, and unrelated to another disease. Secondary Raynaud's occurs as a result of another condition and has an older age at onset; episodes are intensely painful and can be asymmetric and associated wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buerger's Test
Buerger's test is used in an assessment of arterial sufficiency. It is named after Leo Buerger. The ''vascular angle'', which is also called ''Buerger's angle'', is the angle to which the leg has to be raised before it becomes pale, whilst lying down. In a limb with a normal circulation the toes and sole of the foot, stay pink, even when the limb is raised by 90 degrees. In an ischaemic leg, elevation to 15 degrees or 30 degrees for 30 to 60 seconds may cause pallor. (This part of the test checks for ''elevation pallor''.) A vascular angle of less than 20 degrees indicates severe ischaemia. From a sitting position, in normal circulation, the foot will quickly return to a pink colour. Where there is peripheral artery disease the leg will revert to the pink colour more slowly than normal and also pass through the normal pinkness to a red-range colouring (''rubor'' - redness) often known as ''sunset foot''. This is due to the dilatation of the arterioles in an attempt to rid the m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metabolic Waste
Metabolic wastes or excrements are substances left over from metabolic processes (such as cellular respiration) which cannot be used by the organism (they are surplus or toxic), and must therefore be excreted. This includes nitrogen compounds, water, CO2, phosphates, sulphates, etc. Animals treat these compounds as excretes. Plants have chemical "machinery" which transforms some of them (primarily the nitrogen compounds) into useful substances. All the metabolic wastes are excreted in a form of water solutes through the excretory organs (nephridia, Malpighian tubules, kidneys), with the exception of CO2, which is excreted together with the water vapor throughout the lungs. The elimination of these compounds enables the chemical homeostasis of the organism. Nitrogen wastes The nitrogen compounds through which excess nitrogen is eliminated from organisms are called nitrogenous wastes () or nitrogen wastes. They are ammonia, urea, uric acid, and creatinine. All of these substance ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypoxia (medical)
Hypoxia is a condition in which the body or a region of the body is deprived of adequate oxygen supply at the tissue level. Hypoxia may be classified as either '' generalized'', affecting the whole body, or ''local'', affecting a region of the body. Although hypoxia is often a pathological condition, variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise.. Hypoxia differs from hypoxemia and anoxemia, in that hypoxia refers to a state in which oxygen present in a tissue or the whole body is insufficient, whereas hypoxemia and anoxemia refer specifically to states that have low or no oxygen in the blood. Hypoxia in which there is complete absence of oxygen supply is referred to as anoxia. Hypoxia can be due to external causes, when the breathing gas is hypoxic, or internal causes, such as reduced effectiveness of gas transfer in the lungs, reduced capacity of the blood to carry oxygen, compromised general ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ischemia
Ischemia or ischaemia is a restriction in blood supply to any tissue, muscle group, or organ of the body, causing a shortage of oxygen that is needed for cellular metabolism (to keep tissue alive). Ischemia is generally caused by problems with blood vessels, with resultant damage to or dysfunction of tissue i.e. hypoxia and microvascular dysfunction. It also implies local hypoxia in a part of a body resulting from constriction (such as vasoconstriction, thrombosis, or embolism). Ischemia causes not only insufficiency of oxygen, but also reduced availability of nutrients and inadequate removal of metabolic wastes. Ischemia can be partial (poor perfusion) or total blockage. The inadequate delivery of oxygenated blood to the organs must be resolved either by treating the cause of the inadequate delivery or reducing the oxygen demand of the system that needs it. For example, patients with myocardial ischemia have a decreased blood flow to the heart and are prescribed with medi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erection
An erection (clinically: penile erection or penile tumescence) is a physiological phenomenon in which the penis becomes firm, engorged, and enlarged. Penile erection is the result of a complex interaction of psychological, neural, vascular, and endocrine factors, and is often associated with sexual arousal or sexual attraction, although erections can also be spontaneous. The shape, angle, and direction of an erection varies considerably between humans. Physiologically, an erection is required for a male to effect vaginal penetration or sexual intercourse and is triggered by the parasympathetic division of the autonomic nervous system, causing the levels of nitric oxide (a vasodilator) to rise in the trabecular arteries and smooth muscle of the penis. The arteries dilate causing the corpora cavernosa of the penis (and to a lesser extent the corpus spongiosum) to fill with blood; simultaneously the ischiocavernosus and bulbospongiosus muscles compress the veins of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Penis
A penis (plural ''penises'' or ''penes'' () is the primary sexual organ that male animals use to inseminate females (or hermaphrodites) during copulation. Such organs occur in many animals, both vertebrate and invertebrate, but males do not bear a penis in every animal species, and in those species in which the male does bear a so-called penis, the penises in the various species are not necessarily homologous. The term ''penis'' applies to many intromittent organs, but not to all. As an example, the intromittent organ of most cephalopoda is the hectocotylus, a specialized arm, and male spiders use their pedipalps. Even within the Vertebrata there are morphological variants with specific terminology, such as Hemipenis, hemipenes. In most species of animals in which there is an organ that might reasonably be described as a penis, it has no major function other than intromission, or at least conveying the sperm to the female, but in the Eutheria, placental mammals the peni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haemodynamic Response
In haemodynamics, the body must respond to physical activities, external temperature, and other factors by homeostatically adjusting its blood flow to deliver nutrients such as oxygen and glucose to stressed tissues and allow them to function. Haemodynamic response (HR) allows the rapid delivery of blood to active neuronal tissues. The brain consumes large amounts of energy but does not have a reservoir of stored energy substrates. Since higher processes in the brain occur almost constantly, cerebral blood flow is essential for the maintenance of neurons, astrocytes, and other cells of the brain. This coupling between neuronal activity and blood flow is also referred to as neurovascular coupling. Vascular anatomy overview In order to understand how blood is delivered to cranial tissues, it is important to understand the vascular anatomy of the space itself. Large cerebral arteries in the brain split into smaller arterioles, also known as pial arteries. These consist of endothe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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