Kidney

Question 1

Structure of kidney?

Answer 1

Renal artery/vein.
Ureter leading out.
Pelvis
Capsule
Cortex
Medulla

Question 2

Parts of the Nephron?

Answer 2

Renal cortex contains glomerulus and bowman’s capsule.

Renal medulla contains collecting ducts, loop of henle, proximal and distal convoluted tubules.

Question 3

Describe ultrafiltration.

Answer 3

(Cortex)
Wide afferent arteriole narrows to the thin efferent arteriole producing high hydrostatic pressure.

Glomerulus filters by size through capillary endothelium, basement membrane, podocytes, into the bowman’s capsule.

Question 4

Describe selective reabsorption of glucose in the proximal convoluted tubule.

Answer 4

(Cortex)
Sodium ions actively transported into the blood 3 sodium out 2 potassium in.
Establishes a conc gradient for glucose/amino acids to diffuse into the cell from the filtrate with sodium ions through a co transport protein.

Question 5

Describe the countercurrent multiplier system in the loop of henle.

Answer 5

(Medulla)
Descending limb- permeable to water and ions

Ascending limb- permeable to ions only.

AL: Sodium and chloride ions actively transported into tissue fluid of medulla.

DL: lowers WP of medulla tissue, causing osmosis out of filtrate into tissues.

DL: Increases WP of filtrate, increasing ion concentration towards the base of the loop of henle.

AL: Ions diffuse out of filtrate into the tissue fluid, multiplier effect begins to surmount.

Question 6

Describe Osmoregulation in the collecting duct.

Answer 6

Osmoreceptors in hypothalamus detect decrease in water potential (as they lose water).

Causes release of ADH
(Anti-diuretic hormone) from posterior pituitary gland into the blood

ADH travels to kidneys in blood and ADH binds to receptors on the surface of collecting duct and distal convoluted tubule causing them to become more permeable to water

By causing a series of enzyme catalysed reactions resulting in vesicles containing aquaporins fusing the cell membrane.

Permeability of membrane to water is increased so more water moves from the CD and DCT down a water potential gradient (due to high ion concentration in medulla) out of filtrate back into blood.

More water reabsorbed - lower volume of more concentrated urine produced