Everything about Human Homeostasis totally explained
Human homeostasis is the
homeostasis of
humans, for example the property to regulate the internal environment of the body so as to maintain a stable, constant condition.
The
kidneys are major contributors to human homeostasis, regulating in five important ways: regulation of blood water levels, reabsorption of substances into the blood, maintenance of salt and ion levels in the blood, regulation of blood pH, and excretion of urea and other wastes.
Much disease results from disturbance of homeostasis, a condition known as
homeostatic imbalance. For instance,
heart failure has been seen where negative feedback mechanisms become overwhelmed, and destructive positive feedback mechanisms then take over. Diseases which result from a homeostatic imbalance include
diabetes,
dehydration,
hypoglycemia,
hyperglycemia,
gout and any disease caused by a toxin present in the bloodstream. All of these conditions result from the presence of an increased amount of a particular substance. In these cases medical intervention may be required to restore balance, or permanent damage to the organs may result.
Temperature
Humans are
warm-blooded, maintaining a near-constant body temperature. Thermoregulation is an important aspect of human
homeostasis. Heat is mainly produced by the liver and muscle contractions. Humans have been able to adapt to a great diversity of climates, including hot humid and hot arid. High temperatures pose serious stresses for the human body, placing it in great danger of injury or even death. In order to deal with these climatic conditions, humans have developed physiologic and cultural modes of adaptation.
Temperature may enter a circle of
positive feedback, when temperature reaches extremes of 45ºC (113ºF), at which cellular proteins denature, causing the active site in proteins to change, thus causing metabolism stop and ultimately death.
Iron
Iron is an essential element for human beings. The control of this necessary but potentially
toxic substance is an important part of many aspects of human
health and
disease.
Hematologists have been especially interested in the system of iron
metabolism because iron is essential to
red blood cells. In fact, most of the
human body's iron is contained in red blood cells'
hemoglobin, and iron deficiency is the most common cause of
anemia.
When body levels of iron are too low, then
hepcidin in the
duodenal epithelium is decreased. This causes an increase in
ferroportin activity, stimulating iron uptake in the
digestive system. Vice versa in iron surplus.
In individual cells, an iron deficiency causes
responsive element binding protein (IRE-BP) to bind to
iron responsive elements (IRE) on mRNAs for
transferrin receptors, resulting in increased production of transferrin receptors. These receptors increase binding of
transferrin to cells, and therefore stimulating iron uptake.
Blood composition
The balance of many blood solutes belongs to
renal physiology.
Sugar
Humans regulate their blood glucose with
insulin and
glucagon. These hormones are released by the
pancreas.
When blood sugar levels become too high, insulin is released from the pancreas, lowering the blood sugar levels. On the other hand, when blood sugar levels become too low, glucagon is released, increasing blood sugar levels.
If the pancreas is for any reason unable to produce enough of these two hormones
diabetes results.
Fats
Osmoregulation
Osmoregulation is the active regulation of the
osmotic pressure of bodily fluids to maintain the homeostasis of the body's
water content; that's it keeps the body's fluids from becoming too dilute or too concentrated. Osmotic pressure is a measure of the tendency of water to move into one
solution from another by
osmosis. The higher the osmotic pressure of a solution the more water wants to go into the solution.
The
kidneys are used to remove excess ions from the blood, thus affecting the osmotic pressure. These are then expelled as
urine.
Pressure
The renin-angiotensin system (RAS) is a
hormone system that helps regulate long-term
blood pressure and
extracellular v
olume in the body.
Calcium
When blood
calcium becomes too low, calcium-sensing
receptors in the
parathyroid gland become inactivated. This results in the release of
PTH, which acts to increase blood calcium, for example by release from
bones.
On the other hand, excessive blood calcium levels causes an activation of calcium-sensing receptors in the parathyroid gland, resulting in decreased PTH release and a decrease in blood calcium.
Calcitonin works the opposite way, increasing calcium levels.
Acid-base
The kidneys maintain acid-base homeostasis by regulating the pH of the
blood plasma. Gains and losses of acid and base must be balanced. The study of the acid-base reactions in the body is
acid base physiology.
Volume
The body's
homeostatic control mechanisms, which maintain a constant internal environment, ensure that a balance between fluid gain and fluid loss is maintained. The hormones ADH (
Anti-diuretic Hormone, also known as vasopressin) and
Aldosterone play a major role in this.
- If the body is becoming fluid-deficient, there will be an increase in the secretion of these hormones (ADH), causing fluid to be retained by the kidneys and urine output to be reduced.
- Conversely, if fluid levels are excessive, secretion of these hormones (aldosterone) is suppressed, resulting in less retention of fluid by the kidneys and a subsequent increase in the volume of urine produced.
- If you've too much Carbon dioxide(CO2) in the blood, it can cause the blood to become acidic. People respirate heavily not due to low oxygen(O2) content in the blood, but because they've too much CO2.
Hemostasis
Hemostasis is the process whereby bleeding is halted. A major part of this is
coagulation.
Platelet accumulation causes
blood clotting in response to a break or tear in the lining of blood vessels. Another example is the release of
oxytocin to intensify the contractions that take place during childbirth.
Extracellular fluid
The
kidneys by regulating the blood composition, also controls the extracellular fluid homeostasis.
Further Information
Get more info on 'Human Homeostasis'.
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