Life processes class 10 notes part 4 – Human excretory system
EXCRETION IN HUMAN BEING
Excretory system of Human remains located in the abdominal cavity and consists of two kidney, two ureter, bladder and urethra.
Kidney of human is bean shaped, and function is to remove the poisonous substance urea, other waste salts and excess water from blood and excrete them in form of yellow liquid called urine it is due to the presence urochrome pigment in urine. Thus, kidney helps in filtering the blood and removes the toxic wastes in the form of urine throughout the body. Each of kidneys made up of large no of unit called nephron.
Nephron: Each nephron consists of two parts. Malpighian body and tubular parts. And glomerulous while tubular portion consists of P.C.T. Loop of henel and the D.C.T. (Distal convulated tubules).
The blood in the capillaries of glomerulous comes from the aorta via renal arteries & after passing through glomerulous it returns to posterior vena cava via renal veins.
NEPHRON
Blood entering into the glomerulus carries wastes material which is filtered out in the Bowman’s capsule. Wall of glomerular capillaries and bowman’s capsule are very thin are the selectively permeable. Once the waste material is filtered out, blood free from these waste materials goes into the renal veins from where it goes into heart. Fluid containing waste materials is forced out of the glomerular capillaries in the Bowman’s capsule.
The filtered out fluid is known as the glomerular filtrates which contains Na, K & C l, glucose, A. Along with urea, uric acid and large amount of water. During flow of glomerular filtrates usual substances reabsorbed and secretion of certain substances takes place fluid reaches the end of collecting duct is called urine. Human urine contain about 95% water and 5% nitrogenous substances (urea, uric a) finally urine passes through ureter and collects in bladder till thrown out of body by urethra.
Osmoregulation
It is the process of the regulating ion concentration and water content in the body. kidneys not only functions to remove toxic waste, but also act as osmoregulatory organs by controlling the water balance and levels of mineral-ions in the body.
The efficiency of kidney gradually declines with the increase of age. Its activity decline to about 50% by age of 70 in human being. Other cause of decline its function is kidney infection, injury related to blood flow. This will causes the kidney damage or mol functioning. Term for decline in its performance due to a disease called kidney failure.
There two alternative for kidney failure persons.- A matching kidney from a healthy person may be transplanted.
An artificial kidney machine may be employed in order to get rid of metabolic wastes from the blood and to maintain normal levels of H2O and mineral ions in body fluid. Artificial kidney work on principle of natural kidney and procedure is called Dialysis. Finally cleaned blood is pumped back to the patient.
During dialysis heparin (As an anticoagulant substance) adds into blood to prevent clotting.
Renel dialysis
