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Thirst
Thirst is the craving for potable fluids, resulting in the basic instinct of animals to drink. It is an essential mechanism involved in fluid balance. It arises from a lack of fluids or an increase in the concentration of certain osmolites, such as sodium. If the water volume of the body falls below a certain threshold or the osmolite concentration becomes too high, structures in the brain detect changes in blood constituents and signal thirst. Continuous dehydration can cause acute and chronic diseases, but is most often associated with renal and neurological disorders. Excessive thirst, called polydipsia, along with excessive urination, known as polyuria, may be an indication of diabetes mellitus or diabetes insipidus. There are receptors and other systems in the body that detect a decreased volume or an increased osmolite concentration. Some sources distinguish "extracellular thirst" from "intracellular thirst", where extracellular thirst is thirst generated by decreased v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diabetes Insipidus
Diabetes insipidus (DI) is a condition characterized by large amounts of dilute urine and increased thirst. The amount of urine produced can be nearly 20 liters per day. Reduction of fluid has little effect on the concentration of the urine. Complications may include dehydration or seizures. There are four types of DI, each with a different set of causes. # Central DI (CDI), now known as arginine vasopressin deficiency (AVP-D), is due to a lack of vasopressin (antidiuretic hormone) production. This can be due to injury to the hypothalamus or pituitary gland or due to genetics. # Nephrogenic DI (NDI), also known as arginine vasopressin resistance (AVP-R), occurs when the kidneys do not respond properly to vasopressin. # Dipsogenic DI is a result of excessive fluid intake due to damage to the hypothalamic thirst mechanism. It occurs more often in those with certain psychiatric disorders or on certain medications. # Gestational DI occurs only during pregnancy. Diagnosis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dehydration
In physiology, dehydration is a lack of total body water that disrupts metabolic processes. It occurs when free water loss exceeds intake, often resulting from excessive sweating, health conditions, or inadequate consumption of water. Mild dehydration can also be caused by immersion diuresis, which may increase risk of decompression sickness in divers. Most people can tolerate a 3-4% decrease in total body water without difficulty or adverse health effects. A 5-8% decrease can cause fatigue and dizziness. Loss of over 10% of total body water can cause physical and mental deterioration, accompanied by severe thirst. Death occurs with a 15 and 25% loss of body water.Ashcroft F, Life Without Water in Life at the Extremes. Berkeley and Los Angeles, 2000, 134-138. Mild dehydration usually resolves with oral rehydration, but severe cases may need intravenous fluids. Dehydration can cause hypernatremia (high levels of sodium ions in the blood). This is distinct from hypovolemia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polydipsia
Polydipsia is excessive thirst or excess drinking.Porth, C. M. (1990). ''Pathophysiology: Concepts of altered health states''. Philadelphia: J.B. Lippincott Company. The word derives , which is derived . Polydipsia is a nonspecific symptom in various medical disorders. It also occurs as an abnormal behaviour in some non-human animals, such as in birds. Causes Diabetes Polydipsia can be characteristic of diabetes mellitus, often as an initial symptom. It is observed in cases of poorly controlled diabetes, which is sometimes the result of low patient adherence to anti-diabetic medication. Diabetes insipidus ("tasteless" diabetes, as opposed to diabetes mellitus) can also cause polydipsia. Other physiological causes It can also be caused by a change in the osmolality of the extracellular fluids of the body, hypokalemia, decreased blood volume (as occurs during major hemorrhage), and other conditions that create a water deficit. This is usually a result of osmotic diuresis. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diabetes Mellitus
Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained hyperglycemia, high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or the cells of the body becoming unresponsive to insulin's effects. Classic symptoms include polydipsia (excessive thirst), polyuria (excessive urination), polyphagia (excessive hunger), Weight loss#Unintentional, weight loss, and blurred vision. If left untreated, the disease can lead to various health complications, including disorders of the Cardiovascular disease, cardiovascular system, Diabetic retinopathy, eye, Diabetic nephropathy, kidney, and Diabetic neuropathy, nerves. Diabetes accounts for approximately 4.2 million deaths every year, with an estimated 1.5 million caused by either untreated or poorly treated diabetes. The major types of diabetes are Type 1 diabetes, type 1 and Type 2 diabetes, type 2. The most common treatment for ty ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drinking
Drinking is the act of ingesting water or other liquids into the body through the mouth, proboscis, or elsewhere. Humans drink by swallowing, completed by peristalsis in the esophagus. The physiological processes of drinking vary widely among other animals. Most animals drink water to maintain bodily hydration, although many can survive on the water gained from their food. Water is required for many physiological processes. Both inadequate and (less commonly) excessive water intake are associated with health problems. Methods of drinking In humans When a liquid enters a human mouth, the swallowing process is completed by peristalsis which delivers the liquid through the esophagus to the stomach; much of the activity is assisted by gravity. The liquid may be poured from the hands or drinkware may be used as vessels. Drinking can also be by sipping or sucking, typically when imbibing hot liquids or drinking from a spoon. Infants employ a method of suction wherein the lip ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subfornical Organ
The subfornical organ (SFO) is one of the circumventricular organs of the brain. Its name comes from its location on the ventral surface of the fornix near the interventricular foramina (foramina of Monro), which interconnect the lateral ventricles and the third ventricle. Like all circumventricular organs, the subfornical organ is well-vascularized, and like all circumventricular organs except the subcommissural organ, some SFO capillaries have fenestrations, which increase capillary permeability. The SFO is considered a sensory circumventricular organ because it is responsive to a wide variety of hormones and neurotransmitters, as opposed to secretory circumventricular organs, which are specialized in the release of certain substances. Anatomy As noted above, capillaries in some subregions within the SFO are fenestrated, and thus lack a blood–brain barrier. All circumventricular organs except the subcommissural organ contain fenestrated capillaries, a feature that distingu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluid Balance
Fluid balance is an aspect of the homeostasis of organisms in which the amount of water in the organism needs to be controlled, via osmoregulation and behavior, such that the concentrations of electrolytes (salts in solution) in the various body fluids are kept within healthy ranges. The core principle of fluid balance is that the amount of water lost from the body must equal the amount of water taken in; for example, in humans, the output (via respiration, perspiration, urination, defecation, and expectoration) must equal the input (via eating and drinking, or by parenteral intake). Euvolemia is the state of normal body fluid volume, including blood volume, interstitial fluid volume, and intracellular fluid volume; hypovolemia and hypervolemia are imbalances. Water is necessary for all life on Earth. Humans can survive for 4 to 6 weeks without food but only for a few days without water. Profuse sweating can increase the need for electrolyte replacement. Water-electrolyte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Renin
Renin ( etymology and pronunciation), also known as an angiotensinogenase, is an aspartic protease protein and enzyme secreted by the kidneys that participates in the body's renin-angiotensin-aldosterone system (RAAS)—also known as the renin-angiotensin-aldosterone axis—that increases the volume of extracellular fluid (blood plasma, lymph, and interstitial fluid) and causes arterial vasoconstriction. Thus, it increases the body's mean arterial blood pressure. Renin is not commonly referred to as a hormone, although it has a receptor, the (pro)renin receptor, also known as the renin receptor and prorenin receptor (see also below), as well as enzymatic activity with which it hydrolyzes angiotensinogen to angiotensin I. Biochemistry and physiology Structure The primary structure of renin precursor consists of 406 amino acids with a pre- and a pro-segment carrying 20 and 46 amino acids, respectively. Mature renin contains 340 amino acids and has a mass of 37 kDa. Secr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Area Postrema
The area postrema, a paired structure in the medulla oblongata of the brainstem, is a circumventricular organ having permeable capillaries and sensory neurons that enable its role to detect circulating chemical messengers in the blood and transduce them into neural signals and networks. Its position adjacent to the bilateral nuclei of the solitary tract and role as a sensory transducer allow it to integrate blood-to-brain autonomic functions. Such roles of the area postrema include its detection of circulating hormones involved in vomiting, thirst, hunger, and blood pressure control. Structure The area postrema is a paired protuberance found at the inferoposterior limit of the fourth ventricle. Specialized ependymal cells are found within the area postrema. These cells differ slightly from the majority of ependymal cells (ependymocytes), forming a unicellular epithelial lining of the ventricles and central canal. The area postrema is separated from the vagal trigone by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Renin Angiotensin System
Renin (etymology and pronunciation), also known as an angiotensinogenase, is an aspartic protease protein and enzyme secreted by the kidneys that participates in the body's renin-angiotensin-aldosterone system (RAAS)—also known as the renin-angiotensin-aldosterone axis—that increases the volume of extracellular fluid (blood plasma, lymph, and interstitial fluid) and causes arterial vasoconstriction. Thus, it increases the body's mean arterial blood pressure. Renin is not commonly referred to as a hormone, although it has a receptor, the (pro)renin receptor, also known as the renin receptor and prorenin receptor (see also below), as well as enzymatic activity with which it hydrolyzes angiotensinogen to angiotensin I. Biochemistry and physiology Structure The primary structure of renin precursor consists of 406 amino acids with a pre- and a pro-segment carrying 20 and 46 amino acids, respectively. Mature renin contains 340 amino acids and has a mass of 37 kDa. Secreti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angiotensin I
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", later renamed "angiotensin" as a consensus by the 2 groups that independently discovered it) 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angiotensinogen
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", later renamed "angiotensin" as a consensus by the 2 groups that independently discovered it) 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
