Kidneys are two bean-shaped organs that perform several vital functions besides formation of urine. By excreting urine, kidney plays the principal role in homeostasis.
They reside against the back muscles in the upper abdominal cavity. They reside in opposite to each other on both aspects of the backbone. The right kidney sits a little bit lower than the left to accommodate the liver.
The kidneys are multi-functional powerhouses of activity when it comes to components of the urinary system. Some of the core functions of the kidneys are detailed below.
They reside against the back muscles in the upper abdominal cavity. They reside in opposite to each other on both aspects of the backbone. The right kidney sits a little bit lower than the left to accommodate the liver.
The kidneys are multi-functional powerhouses of activity when it comes to components of the urinary system. Some of the core functions of the kidneys are detailed below.
ROLE IN HOMEOSTASIS
The primary function of the kidney is homeostasis. Homeostasis is the maintenance of internal environment from the harms of fluctuations in the external environment. Kidney accomplished this by the formation of urine, kidneys regulate various activities in the body, which are concerned with homeostasis such as.
- Excretion of waste products. Kidneys excrete the unwanted waste products, which are formed during metabolic activities:
- Urea (cease manufactured form of amino acid metabolism)
- Uric acid (cease manufactured form of nucleic acid metabolism)
- Creatinin (cease manufactured form of metabolism in muscles)
- Bilirubin (cease manufactured form of hemoglobin degradation)
- Maintenance of Electrolyte Balance. Preservation of electrolyte balance, mainly sodium is in relation to water balance. Kidneys reserve sodium if the osmolarity of body water decreases and do away with sodium when osmolarity increases. It does this via lively shipping of sodium from the proximal tubule of the nephron.
- Preservation of Water Balance. Kidneys hold the water stability in the body via conserving water, whilst it is reduced and excreting water while it is far in extra in the body. This is a crucial process for homeostasis in the body.
- Maintenance of Acid-Base Balance. The pH of blood and body fluids must be maintained within a narrow variety for a healthful dwelling. It is achieved with the aid of the characteristic of kidneys. A pair of the kidneys prevents the body from developing acidosis via disposing of certain metabolic acids like sulphuric acid and phosphoric acid.
REGULATION OF BLOOD CALCIUM LEVEL
Kidneys play a position inside the regulation of blood calcium degree via activating 1,25-dihydroxycholecalciferol into vitamin D. Vitamin D is essential for the absorption of calcium from the intestine.
HEMATOPOIETIC FUNCTIONS
Kidneys stimulate the production of the erythrocytes by secreting erythropoietin. Erythropoietin is the important stimulating factor for erythropoiesis. Kidney also secrets another factor called thrombopoietin, which stimulates the production of thrombocytes.
REGULATION OF BLOOD PRESSURE
Kidneys play an important role in long-term regulation of arterial blood pressure by two ways:
- With the aid of regulating the quantity of extracellular fluid.
- Through renin-angiotensin mechanism.
Renin is secreted by the juxtaglomerular apparatus of the nephron. when released into the blood it acts on the plasma protein called angiotensinogen or renin substrate. By a series of complex reactions, it converts renin substrate into the angiotensin 2. The actions of angiotensin 2 in maintaining blood pressure are:
1. On Blood Vessels:
It increases atrial blood pressure by directly acting on the blood vessels and causing vasoconstriction. It does this also indirectly by increasing the release of noradrenaline from postganglionic sympathetic fibers.
2. On Adrenal Cortex:
It stimulates adrenal cortex to secrete aldosterone. It acts on renal tubules and increases retention of sodium, which is also responsible for the elevation of blood pressure.
3. On Kidneys:
It constricts the efferent arteriole of the glomerulus to regulate glomerular filtration rate, which causes a decrease in filtration after an initial increase.
ENDOCRINE FUNCTIONS
Kidneys secrete many hormonal substances in addition to erythropoietin and thrombopoietin. Some of the main hormones are listed below:
- Renin
- Prostaglandins
- Erythropoietin
- 1,25-dihydroxycholecalcifeferol
- Thrombopoietin
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