Question

how does the vessel diameter of the afferent arteriole change in order to decrease glomerular hydrostatic pressure (ghp) and restore the glomerular filtration rate (gfr) to normal?

Answer 1

Answer:

Nephron of the kidneys is the cells which are associated with the process of urine formation. They are divided into two divisions;

Renal corpuscle and the renal tubule

Components of the renal corpuscle: Glomerulus and the Bowman’s capsule

Components of the renal tubule: proximal convoluted tubule, loop of Henle, Distal convoluted tubule

Glomerulus: It is a tuft of capillaries which brings in the blood to the nephron for filtration

Bowman’s capsule: It is a sac like structure which provides support to the glomerulus

In the renal tubule, the reabsorption of all the essential components of the filtrate occurs.

Mechanism of urine formation is divided into three stages namely;

1. Glomerular filtration

2. Tubular reabsorption and

3. Tubular secretion

And there is a definite and a constant pressure which is required for the process of urine formation to occur. During the pressure variations, the glomerulus of the nephron is regulated by the myogenic as well as auto regulatory mechanisms which helps control the process of urine formation.

As a part of the myogenic regulatory mechanism; the afferent arteriole entering can constrict or dilate their lumen thereby resisting the pressure changes.

As for an example, when the blood pressure within the body rises, the lumen of the afferent arteriole bringing blood for filtration reduces. This thus reduces the blood blow within the nephron for filtration and likewise the glomerular filtrate formed gets maintained by their amount getting reduced in response to the high blood pressure.

Similarly, when there is a drop in the blood pressure, the lumen of the afferent arteriole bringing blood for filtration gets increased due to which more blood is carried for filtration to take place thus restoring the filtrate thus formed.

Thus in this way in response to the blood pressure variation, there is also a myogenic mechanism which leads to maintain the balance between the variations in the blood pressure and the urine output.