The nephron

Question 1

Where does ultrafiltration occur?

Answer 1

glomerulus and Bowman’s capsule

Question 2

How does the glomerulus create high pressure?

Answer 2

afferent arteriole supplying the glomerulus is wider than the narrow efferent arteriole leaving

Question 3

What are the 3 filters in ultrafiltration?

Answer 3

capillary wall of glomerulus, basement membrane and podocytes

Question 4

What cant pass into the Bowman’s capsule?

Answer 4

cells, platelets or large plasma proteins

Question 5

What filtrate enters the Bowman’s capsule?

Answer 5

glucose, urea, sodium, chloride, water, vitamins, hormones, amino acids

Question 6

What is the role of reabsorption?

Answer 6

returning water, glucose and salts back to the blood

Question 7

What is the name of the first tubule for reabsorption?

Answer 7

proximal convoluted tubule

Question 8

What are the adaptations of the PCT?

Answer 8

1. microvilli to increase SA for reabsorption
2. lots of mitochondria for energy for active transport

Question 9

What substances exit the PCT to return to the blood?

Answer 9

glucose, amino acids, vitamins, hormones and 85% of water, sodium and chloride.

Question 10

How does water and sodium chloride get reabsorbed in the PCT?

Answer 10

water and chloride move down conc gradient out of nephron. Sodium is actively transported out

Question 11

What is the conc. of the fluid that reaches the loop of henle?

Answer 11

isotonic

Question 12

What is the role of the loop of henle?

Answer 12

to produce urine that is more concentrated than the blood

Question 13

What moves out the descending limb?

Answer 13

water in the lower part as upper part is impermeable

Question 14

What is the concentration of the fluid that reaches the hairpin of loop of henle and why?

Answer 14

hypertonic as descending limb is impermeable to sodium or chloride so they remain in the filtrate

Question 15

What happens in the first section of the ascending limb?

Answer 15

sodium and chloride diffuses out down conc. gradient

Question 16

How does sodium and chloride leave the upper section of ascending limb?

Answer 16

actively transported out

Question 17

What is the concentration of salts in the medulla of kidney?

Answer 17

highly concentrated

Question 18

What is the concentration of the fluid at the top of the ascending limb?

Answer 18

hypotonic and very dilute

Question 19

How is the permeability of the walls of the DCT altered?

Answer 19

ADH is release from the pituitary gland

Question 20

What happens in the DCT if the body lacks salt?

Answer 20

sodium ions are actively pumped out and chloride ions follow down electrochemical gradient

Question 21

What happens in the DCT if the body wants to conserve water?

Answer 21

ADH is released which makes DCT walls more permeable to water and it leaves via osmosis

Question 22

What is the role of the collecting duct?

Answer 22

to determine the final vol. and conc. of the urine

Question 23

What happens to urine if more water leaves the collecting duct?

Answer 23

becomes more concentrated and less of it

Question 24

How does the countercurrent multiplier system of the Loop of Henle work?

Answer 24

level of sodium in medulla becomes more concentrated further down, so there’s always a higher water potential in the convoluted tubule meaning water can always move out the whole way down

Question 25

How is the permeability of the collecting duct affected?

Answer 25

releasing ADH from the pituitary gland