Dialysis in Human Excretory System

In medicine, Dialysis is also known as renal dialysis, hemodialysis, or kidney dialysis. It is the method of extracting blood from a patient whose kidney function is impaired, purifying it with dialysis, and then adding it to the patient's bloodstream. Hemodialyzer or artificial kidney is a machine, which provides a means for removing certain undesirable substances from blood or adding required components to it. By these particular processes, the apparatus may control the acid-base balance of the blood, including its content of dissolved materials and water.

Dialysis Treatment - Introduction 

In 1945, Dialysis was first used to treat human patients, such as replacing or supplementing the kidneys' action in a person suffering from chronic or acute renal failure or from poisoning by diffusible substances, such as bromides, barbiturates, or aspirin. Usually, the blood is diverted from an artery, one in the wrist, into the dialyzer, in which it flows either by its own respective impetus or with the mechanical pump's aid - along one membrane's surface.

Finally, the blood passes via a trap, which removes bubbles, clots, and returns to a vein in the forearm of the patient. In persons with chronic kidney failure, who need frequent dialysis, repeated surgical access to the blood vessels that are used in the treatments is obviated by a provision of an external plastic shunt between them.

Function of Dialysis 

The secretion of hormones, which affect blood pressure and cannot be duplicated, is another known feature of the natural kidney. Many modern dialyzers rely on the two physicochemical principles, ultrafiltration, and dialysis.

In dialysis, two liquids separated by a porous membrane exchange those components, which exist as particles small enough to diffuse via pores. When the blood is brought to contact with a single side of such a membrane, the dissolved substances (including inorganic salts and urea) pass via a sterile solution placed on the membrane's other side. Since the particles are too huge, white and red cells, proteins, and platelets cannot pass through the membrane.

To limit or prevent the diffusible loss of substances required by the body, such as amino acids, sugars, and required amounts of salts, such compounds are added to the sterile solution; hence their diffusion from the blood is offset by an equal movement in the opposite direction. The shortage of diffusible materials in the blood can be remedied by including them in the solution, where they join the circulation.

Although water easily passes via the membrane, it is not removed by dialysis since its concentration in the blood is less than that in the solution; indeed, water tends to pass from the solution into the blood. The blood's dilution that would result from this particular process is prevented by ultrafiltration, where some of the water, along with few dissolved materials, is forced via membrane by maintaining the blood at higher pressure than the solution.

Symptoms for Dialysis Treatment? 

The following symptoms associated with kidney failure may or may not point to being indications of needing a dialysis treatment: 

• A sudden and/or persistent change in urination

• A metallic taste in the mouth, known as ammonia breath

• Itching or pruritus

• Fatigue

• Nausea followed by throwing up

• Aversion from protein

• Loss of appetite

• Swelling

Types of Dialysis

Let us look at the types of dialysis and the dialysis procedure.

There exist three primary and two secondary types of dialysis, which are

• Hemodialysis dialysis (primary)

• Peritoneal dialysis (primary)

• Hemofiltration dialysis (primary)

• Hemodiafiltration dialysis (secondary)

• Intestinal dialysis (secondary)

• Hemodialysis Procedure In hemodialysis, the patient's blood is pumped into the dialyzer's blood compartment (using a hemodialysis machine), where it is exposed to a partly permeable membrane. Then, the dialyzer is composed of thousands of tiny and hollow synthetic fibres, and the fibre wall acts as a semipermeable membrane. Blood circulates through fibres, dialysis solution circulates around the outside of the fibres, and wastes and water circulate between the two solutions. Then, the cleansed blood can be returned through the circuit back to the body. Ultrafiltration takes place by increasing the hydrostatic pressure across the dialyzer membrane usually; this can be done by applying negative pressure to the dialyzer's dialysate compartment.

• Peritoneal Dialysis In the case of peritoneal dialysis, a sterile solution with glucose (known as dialysate) is run via a tube into the abdominal body cavity around the intestine, the peritoneal cavity, where the peritoneal membrane will act as a partially permeable membrane.

• Hemofiltration Hemofiltration is the same treatment as hemodialysis, but it will make use of a varied principle. The blood is pumped via "hemofilter" or dialyzer as in dialysis, but no dialysate can be used. A pressure gradient will be applied, and as a result, water will quickly pass through the very permeable membrane, "dragging" many dissolved substances along with it, including those with extremely large molecular weights that are not cleared by hemodialysis.

• Hemodiafiltration Hemodiafiltration is given as a combination between hemofiltration and hemodialysis, hence used to purify the blood from toxins when the kidney is not functioning normally and also used to treat the acute kidney injury (AKI).

• Intestinal Dialysis In the case of intestinal dialysis, the diet can be supplemented with soluble fibres like acacia fibre that is digested by the colon's bacteria. This particular bacterial growth increases the amount of nitrogen, which is eliminated in the faecal waste. A secondary native approach utilises the ingestion from 1 to 1.5 litres of non-absorbable solutions of mannitol or polyethylene glycol every fourth hour.

Conclusion

Did you know? Earlier, the membranes that were used for dialysis were procured from animals. It was in the late 1960s, that other materials like hollow filaments made out of synthetic and/or cellulosic materials were used for dialysis. To get more information, study materials, questions on dialysis you can register at Vedantu.com.