Nephron structure

Question 1

What arteriole enters the nephron?

Answer 1

Afferent

Question 2

What is the glomerulus?

Answer 2

a bundle of lots of capillaries, made up when the afferent arteriole branches out forming lots of capillaries

Question 3

Where is the glomerulus found?

Answer 3

the renal capsule

Question 4

What branches out from the renal capsule?

Answer 4

the proximal convoluted tubule

Question 5

What is the function of the nephron?

Answer 5

filter the blood to remove waste and selectively reabsorb useful substances back in to the blood

Question 6

What does urine not contain? (in a healthy person)

Answer 6

proteins and blood cells- too big
glucose - is selectively reabsorbed

Question 7

What does urine contain?

Answer 7

mineral ions
water
urea
small substances

Question 8

What happens in the glomerulus?

Answer 8

ultrafiltration forces out water and small molecules due to high hydrostatic pressure. These enter the renal capsule

Question 9

What happens at the loop of Henle?

Answer 9

Na+ gradient maintained, so water can be reabsorbed by the blood

Question 10

What arteriole leaves the renal capsule?

Answer 10

efferent

Question 11

How are the cells lining the proximal convoluted tubule adapted to it’s function?

Answer 11

• cells have microvilli that create large SA for reabsorption of glucose
• cells have lots of mitochondria which produce the ATP needed for active transport

Question 12

Why is the [Na+] low in the PCT cells?

Answer 12

Na+ is actively transported into the blood

Question 13

Why does a low concentration of Na+ ions in the cells lead to glucose being absorbed?

Answer 13

Na+ can diffuse down its conc. gradient through a co-transport protein. The co-transport protein carries glucose also

Question 14

Why cant water move out in the ascending limb of the loop of Henle?

Answer 14

the walls are impermeable

Question 15

What happens in the ascending limb?

Answer 15

Na+ ions are actively transported out, into the interstitial space

Question 16

What does the increase in Na+ ions do?

Answer 16

lowers water potential in interstitial space

Question 17

What happens at the base of the loop of Henle?

Answer 17

some Na+ ions diffuse into the interstitial space

Question 18

Describe the liquid that enters the distal convoluted tubule

Answer 18

very dilute (as Na+ ions moved out, however still has higher WP than medulla so moves out by osmosis

Question 19

How is glucose reabsorbed in the PCT?

Answer 19

• Na+ actively transported out of Epithelial cells lining PCT (into blood)
• forms conc. gradient, so Na+ diffuse down conc gradient into epithelial cells from the lumen
• through co-transport protein, which takes glucose with it
• diffuses into blood via facilitated diffusion

Question 20

How is water reabsorbed in the Loop of Henle?

Answer 20

• Na+ actively transported out of ascending limb, which is impermeable to water
• low water potential in the medulla
• water moves out of descending limb, into the medulla by osmosis
• water potential in the medulla decreases as you go down the loop of Henle so WP gradient maintained

Question 21

How is the PCT adapted for its function?

Answer 21

• microvilli; large SA for reabsorption
• infoldings; large SA to transfer substances into capillaries
• lots of mitochondria for AT

Question 22

How might length of loop of Henle change depending on the environment they live in? why?

Answer 22

drier environments = longer loop of Henle
so more water absorbed along the whole length

Question 23

What is the gross structure of the kidney? (go from the outside in)

Answer 23

• capsule
• cortex
• medulla
• pelvis
• ureter