Regulation of Internal Environment (Homeostasis)

Homeostasis is the regulation of internal environment of the body so as to maintain a steady  state by self-regulating adjustment .or homeostasis is the maintenance of a fairly constant internal environment of an organism .This self-regulating adjustment  provides optimum  conditions for normal and efficient functioning of the body  cells thereby preventing the damage of the cells. Homeostasis takes place at all levels of living organism .In one celled organism such as amoeba the adjustment involves the whole body using contractile vacuole to collect and expel excess water while higher animal such as mammals, the adjustment are the tissues, organs and system levels .Structure that carry out these homeostasis in the mammalian body are the kidney , liver , skin, hormones and brain.

Regulating functions of kidney.

1. i) Osmoregulation (water balance in the body) is defined as the process by which living organisms balances the amount of water to mineral salts in its body fluids.

When the body contains small quantity of water and at the same time loosing water through sweating such as during exercise the body start conserving water to prevent damaging the body cell due to loss of water, the osmotic pressure of the blood changes, the osmoreceptor in the hypothalamus in the brain detect the changes in the osmotic pressure in the blood as the water content drops. The pituitary gland is simulated to release more ADH (anti diuretic hormones or vasopressin into the blood thus making the wall of the kidney tubules to be more permeable to water and so water is reabsorbed into the blood by osmosis.

When there is too much water in the blood, the hypothalamus in brain releases less ADH into the blood making the wall of the kidney less permeable to water so that less water is reabsorbed by osmosis

ii)Excretion of urea – the kidney removes urea as waste product of metabolism from the body.

iii)Maintenance of acids-base balance of the body.- the acid-base balance of the body fluid is maintained by the kidney . The PH of human blood is between 7.35 and 7.45           (neutral). Anything below or above this range is dangerous to the body. if the acid content of the blood get higher, the cells of the distal convoluted tubules reabsorb more hydroxyl ions (OH) from the urine and more hydrogen ions (H+) or acid are therefore excreted with the urine . On the other hand, if the hydroxyl ions content of the  blood get higher , less  hydrogen ions are produced by the cells of distal convoluted tubule while more hydroxyl ions   are excreted with the urine. In this way, the acid-base balance of the body is maintained

iv). The kidney eliminates undesirable substances such as drug, alcohol and toxins

v)The kidney helps to maintain the osmotic pressure of the blood by regulating the amount of mineral salt in the blood.

External Macro anatomy of kidney