Topic 9

Question 1

nephron

Answer 1

the nephron is the functional unit of the kidney. There are 1-2 million per kidney.

Question 2

Ultrafiltration

Answer 2

Glomerulus
Blood enters the glomerulus via afferent arteriole which runs from the renal artery. So this blood is under relatively high pressure. Blood leaves the glomerulus via efferent arteriole to renal vein.

The hydrostatic pressure in the capillary forces small molecules to pass out of blood and into the bowman capsule. This inculdes urea,water,glucose and amino acids. Bowmans capsule contains specialised cells called podocytes

Podocytes have feet like extensions called pedicels, which are wrapped around outside the capillary. Gaps between the pedicles allow only small molecules to pass through into the bowman’s capsule

Useful molecules (glucose and amino acids) are returned back into the blood. Selective reabsorption which takes in the proximal convoluted tubule

Question 3

proximal tubule

Answer 3

The wall of the proximal tubule has adaptations for rapid absorption, including a large surface area due to microvilli and ATP readily available from many mitochondria.

Question 4

vasa recta

Answer 4

is the group of capillaries that drop into the medulla and return to the cortex. the direction of blood flow in the vasa recta is opposite to that of the fluid in the tubules, which is a countercurrent flow.