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Flashcards in KIDNEYS Deck (26)
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1
Q

what is the function of the kidneys

A

to excrete waste (urea)

to regulate blood water potential

2
Q

how does blood enter the kidneys

A

through the renal artery

3
Q

where does ultafiltration tank place

A

the glomerulus and bowmans capsule

4
Q

which arteriole takes blood into the glomerulus

A

afferent arteriole

5
Q

which arteriole takes filtered blood away the glomerulus

A

efferent arteriole

6
Q

how do you generate high pressure in the glomerulus causing ultrafiltration

A

The afferent arteriole (opening) is wider than the efferent arteriole (closing) therefore blood is at high pressure in glomerulus

7
Q

what is passed onto bowmans capsule in ultrafiltration

A

liquid and small molecules into bowmans capsule

8
Q

what are the 3 layers the liquid and small molecules have to pass through to get from the capillary to the bowmans capsule

A

the capillary wall
the basement membrane
epithelium of bowmans capsule

9
Q

what is the glomerular filtrate and what does it consist of

A

the large molecules that can to fit through the membrane into the bowmans capsule and therefore stay in the blood
eg proteins and blood cells

10
Q

what happens next to glomerular filtrate from stage 1

A

it passes along the nephron to the PCT (proximal convoluted tubule), loop of Henle and DCT (distal convoluted tubule) where selective reabsorption happens

11
Q

what does the PCT wall have on it

A

microvilli

providing a large SA for the reabsorption of useful materials from the glomerular filtrate into the blood

12
Q

What is reabsorbed along the PCT and how

A

glucose is selectively reabsorbed

by active transport and facilitated diffusion

13
Q

what is urine made up of

A
water
urea
dissolved salts
hormones
excess vitamins
14
Q

where is water reabsorbed

A

PCT
Loop of henle
DCT
Collecting duct

15
Q

state 2 ways water is lost

A

urea

sweat

16
Q

what is osmoregulation

A

the regulation of water potential

17
Q

what happens if water potential is too low

A

if water potential is too low
more water reabsorbed by osmosis into blood from nephron
Means urine is more concentrated, so less water lost during excretion

18
Q

what happens if water potential is too high

A

if water potential is too high
less water reabsorbed by osmosis into blood from nephron
Means urine is more dilute, so more water lost during excretion

19
Q

where along the nephron is water potential regulated

A

loop of henle
DCT
collecting duct

20
Q

what 2 limbs make uptake loop of henle

A

the ascending and descending limb

21
Q

what is the gap called in between the 2 limbs

A

the medulla

22
Q

how does the loop of henle maintain the Na+ ion electrochemical gradient

A

At the top of the ascending limb Na+ ions are pumped out by activeT
Ascending limb impermeable to water so water remains inside
This movement of Na+ ions into medulla lowers the water potential
Then water moves via osmosis (high to low) from the descending limb into the medulla (descending limb = permeable to water)
At the bottom of the ascending limb Na+ ions diffuse into the medulla, again lowering water potential
Water then moves out of the DCT by osmosis and is reabsorbed into the blood
Water also moves out of the collecting duct

23
Q

what cells monitor water potential of the blood

A

osmoreceptors

24
Q

where in the brain is blood water potential regulated

A

hypothalamus

25
Q

when your dehydrated what happens to blood ADH levels

A

Water content of blood drops
Water potential drops
Osmoreceptors in hypothalamus detect a change
Posterior pituitary gland is stimulated to release MORE ADH into blood
More ADH means DCT and collecting duct more permeable to water
More water is reabsorbed from tubules into medulla and blood via osmosis
A small amount of conc urine is produced
Meaning less water lost from the body

26
Q

when your hydrated what happens to blood ADH levels

A

Water content of blood increases
Water potential increases
Osmoreceptors in hypothalamus detect a change
Posterior pituitary gland is stimulated to release LESS ADH into blood
Less ADH means DCT and collecting duct less permeable to water
Less water is reabsorbed from tubules into medulla and blood via osmosis
A large amount of dilute urine is produced
Meaning more water lost from the body