Biology · Excretory Products and Their Elimination · NEET
No. Uremia is the accumulation of urea in the blood because the kidneys are not filtering properly. NCERT says it is highly harmful and may lead to kidney failure. So uremia is the toxic condition; kidney failure is the loss of kidney function that uremia can progress to. In NEET wording, uremia = urea in blood, not the same as failure.
This is the key NEET point. The fluid matches plasma in salts and glucose so useful substances have no concentration gradient and stay in the blood. Only nitrogenous wastes (urea, uric acid) are absent from the fluid, so ONLY they move out down the gradient. If the fluid were plain water, glucose and salts would also be lost.
Heparin is an anticoagulant. Blood taken from an artery could clot inside the machine tubes, so heparin is added to keep it flowing. Before returning the cleared blood to the body through a vein, anti-heparin (protamine) is added so the blood can clot normally again inside the body. Order: artery to heparin to dialyser to anti-heparin to vein.
The cellophane tube is a porous (selectively permeable) membrane and movement is by diffusion along the concentration gradient. Since urea and other nitrogenous wastes are high in blood but absent in the dialysing fluid, they diffuse out. Glucose and ions are equal on both sides, so no net loss. There is no pump or active transport here.
It only cleans the blood. The artificial kidney filters wastes but cannot do the kidney's hormone jobs, so it does not activate vitamin D (calcium absorption drops) or make erythropoietin (RBC production drops). NCERT calls kidney transplantation the ultimate correction for acute renal failure; dialysis is a supportive boon, not a permanent cure.
Use of an artificial kidney during hemodialysis may result in: (a) Nitrogenous waste build-up in the body (b) Non-elimination of excess potassium ions (c) Reduced absorption of calcium ions from gastro-intestinal tract (d) Reduced RBC production Which of the following options is the most appropriate?
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Uremia is the harmful accumulation of urea in the blood due to malfunctioning kidneys, which may lead to kidney failure.
It is a dialysing unit containing a coiled cellophane (selectively permeable) tube surrounded by dialysing fluid; wastes diffuse from blood in the tube into the fluid.
It has the same composition as blood plasma EXCEPT that it contains no nitrogenous wastes, so only those wastes diffuse out of the blood.
Heparin is added to the blood entering the dialyser; anti-heparin is added before the cleared blood is returned to the body through a vein.
Kidney transplantation is the ultimate correction for acute renal failure; a kidney from a close relative is preferred to reduce immune rejection.
