Question

How kidney functions are regulated? Add a note on kidney transplantation?

Answer 1

1) Hypothalamus juxtaglomerular apparatus (JGA) and heart are the three important coordinators for the proper working of kidneys.

2) In the hypothalamus, there are osmoreceptors. When the body fluid is at high concentration, then the osmoreceptors in the hypothalamus are activated.

3)This releases ADH or antidiuretic hormone from neurohypophysis which increases the permeability of renal tubules. This, in turn, stimulates increased absorption of water.

4) So urine becomes concentrated as there is the prevention of loss of water from the kidneys. So, the volume of the body fluid increases.

5)This cause osmoreceptors in the hypothalamus to become suppressed. ADH level thus falls down.

6) It has an effect on blood pressure, an increase in ADH cause increase in blood pressure and subsequent increase in glomerular filtration rate (GFR).

7)Fall in GFR activates JG cells to release renin, which converts angiotensinogen to angiotensin which is secreted by the liver and is present in the blood.

8) Lung secretes the angiotensin converting enzyme which converts angiotensin I to II.

9) Angiotensinogen is vasoconstrictor which stimulates adrenal cortex to secrete aldosterone which increases blood pressure and GFR.

10) The heart produces Atrial Natriuretic Factor (ANF) which is secreted when blood flow in atria increases. ANF causes vasodilatation and decreases blood pressure.

Kidney Transplantation:

1) It is done on patients with the end-stage renal disease.

2) It is of two types which depend on the source of the donor organ: a) deceased donor or cadaveric b) living donor transplantation.

3) Living donor are classified into genetically related or non-related.

4) In living donor related transplant, relative with biological relation donates the kidney.

5) The unrelated donor is not biologically related.