Unit 11.3 - The Kidney

Question 1

What is the function after the renal artery

Answer 1

the afferent arterioles (which have a short lumen) increase the pressure of the blood before the glomerulus in the bowman’s capsule. Then the efferent arterioles carries the blood back to the heart. In the glomerulus ultrafiltration occurs due to the existence of small pores in the bowman’s capsule, which allows molecules that are small (simple molecules like glucose, ions, urea, amino acids) but primarily blocking erythrocytes from entering.

Question 2

What happens after the Bowman’s capsule

Answer 2

In the proximal convoluted tubule, selective reabsorption occurs, whereby necessary ions, such as calcium are absorbed, glucose, as well as potassium. This also causes some water to be absorbed via osmosis as a solute gradient occurs.

Question 3

What happens in the loop of Henle

Answer 3

In the descending loop, only water is permeable, but due to the salty conditions present in the medulla, this causes water to osmose into the medulla. In the ascending loop only salt is permeable, this causes the salt to diffuse into the ascending loop.

Question 4

What happens in the collecting duct

Answer 4

In the collecting duct, it is normally impermeable to water and travels straight to the ureter for eventual excretion. However, if water is needed to be reabsorbed due to conditions such as dehydration then the posterior lobe of the pituitary gland will secrete ADH, which then causes aquaporins to increase the permeability of the collecting duct via pore creation, and due to the nature of the medulla (being salty), water will diffuse via osmosis out of the duct and into the medulla.