Excretory Disorders

For the removal of waste products from the human body to keep homeostasis, an excretory system is necessary. Through metabolism, these products are formed and removed in the form of sweat, urine, and feces.  In the process of excretion, some excretory organs include kidneys, sweat glands, liver, and large intestine. When one or more excretory organs stop working properly. It causes excretory disorders.

Haemodialysis 

Haemodialysis utilizes the procedure of diffusion over a semipermeable membrane to detach undesirable, poisonous material from the blood while attaching desirable elements.  A continuous flow of blood on one side of the semipermeable membrane and a cleaning solution (dialysate) also permit the moving of waste products from the blood. 

In this method, a dialysis machine or artificial kidney is attached to the patient’s body. It is worked in the case of uremia (blood with an excess of urea). In this, blood from an artery of the patient is redirected by dialysing a membrane after refrigerating it to 0°C and intermixing it with an anti-coagulant (heparin). Dialysing membrane has openings identical to those of glomerular capillaries and functions as a superfine strainer. This cellophane membrane is impermeable to macromolecules such as plasma proteins but is permeable to micromolecules such as urea, uric acid, creatinine, and mineral ions. This tune is submerged in a solution called dialysate. Dialysate is isotonic to blood plasma except for the nitrogenous wastes, for which it is hypotonic to blood plasma. In consequence, the wastes such as urea, uric acid, creatinine, excess H⁺ ammonium salts, etc. from blood spread over the membrane into the dialysate. The dialysate is swapped as and when needed. Blood from the dialyser goes back to the body by a vein after warming it to the body temperature and combining it with an antiheparin.

Advantage of Haemodialysis 

1. Little treatment time and least interruptions of lifestyle between treatments.
2. Patients can guide to a greater extent or smaller normal life.
3. It can too help in the recovery of reversible kidney injury.
4. No part of the apparatus is the shaped interior of the body. 
5. Bacteria and viruses are unable to go through it. 

Animals by metabolic activities collect ammonia, urea, uric acid, carbon dioxide, water and ions such as Na⁺, K⁺, Cl^–, phosphate, sulphate, etc. These substances need to be removed. Nitrogenous wastes such as ammonia, urea, and uric acid are excreted by the animals. Ammonia is more destructive than uric acid. Hence, ammonia needs a large amount of water and uric acid needs less amount of water for its elimination. Ammonotelism is the procedure of excreting ammonia. Numerous bony fishes, aquatic amphibians, and aquatic insects are ammonotelic in nature. Ammonia is normally excreted by diffusion across body surfaces or through gill surfaces (in fishes) as ammonium ions because ammonia is willingly soluble. For its removal, kidneys do not play any remarkable role. Terrestrial conversation required the manufacturing of lesser destructive nitrogenous wastes such as urea and uric acid in order of conserving water. Mammals, numerous terrestrial amphibians, and marine fishes mostly excrete urea and are called Ureotelic animals. Ammonia manufactured by metabolism is changed into urea in the liver of these animals and free into the blood, which is purified and excreted out by the kidneys. Some quantity of urea possibly continued in the kidney matrix of some of these animals to keep a wanted osmolarity. Reptiles, birds, land snails, and insects excrete nitrogenous wastes as uric acid in the shape of pellets or paste with a minimal loss of water and are called uricotelic animals.