5.3 Kidneys & Osmoregulation Flashcards Preview

A Level Biology > 5.3 Kidneys & Osmoregulation > Flashcards

Flashcards in 5.3 Kidneys & Osmoregulation Deck (35):
1

what is osmoregulation?

controlling water potential of blood within very narrow boundaries

2

what sorts of things can put the osmotic stress on the body?

salty foods
drinking a lot
exercise
fevers
hot climates

3

what could happen is kPa was not kept stable?

damage or even death

4

what is crucial to maintaining kPa, regardless of water sources is taken in or lost?

changing the concentration of urine

5

amount of water lost in urine is controlled by which hormone? in what sort of system?

ADH
negative feedback system

6

ADH is produced by the hypothalamus and secreted where?

posterior pituitary where it is stored

7

what does ADH do to the collecting duct and distal convoluted tubule?

changes their permeability to water

8

ADH is released from pituitary and travels in the blood till it binds to receptors where?

on cell membrane of tubule cells

9

when ADH binds it triggers the formation of what?

cyclic AMP

10

Cyclic AMP is a second messenger, what is this?

a molecule relaying signals received at cell surface to molecules inside the cell

11

cAMP causes vesicles in the cells lining the collecting duct to do what?

fuse with cell surface membranes in contact with tissue fluid of medulla

12

membranes of the vesicles contain what?

aquaporins

13

what are aquaporins?

protein based water channels which are inserted into the cell surface membrane making it permeable to water

14

what do aquaporins provide?

a route for water to move out of tubule cells into tissue fluid of medulla and blood capillaries by osmosis

15

the more ADH released, the more aquaporins inserted making what easier?

water to leave tubule cells by osmosis resulting in a small amount of concentrated urine

16

when water is returned to tissue fluid and blood capillaries what does it maintain?

kPa

17

what happens when ADH levels fall?

levels of cAMP fall
aquaporins removed from tubule membrane and are enclosed in vesicles
collecting duct impermeable to water
large amounts of dilute urine

18

control of ADH levels is done by a negative feedback system involving which receptors?

osmoreceptors in the hypothalamus

19

what are osmoreceptors sensitive to?

the concentrations of inorganic ions in the blood

20

(little water) when concentration of inorganic ions in the blood increases what happens to its kPa?

it becomes more negative

21

(little water) what detects the change in kPa?

osmoreceptors

22

(little water) what do the osmoreceptors do?

send nerve impulses to posterior pituitary which releases ADH

23

(little water) ADH binds to receptors on collecting duct and has what effect?

increases permeability to water

24

(little water) water leaves filtrate and diffuses into blood by osmosis producing what?

small amount of concentrated urine

25

(excess of water) blood becomes more dilute with an excess of water, what effect does this have on kPa?

less negative

26

(excess of water) the change is detected by what?

osmoreceptors

27

(excess of water) what happens to the nerve impulses to the posterior pituitary?

reduced or stopped and release of ADH inhibited

28

(excess of water) what happens to the walls of the collecting duct?

remain impermeable to water little reabsorption takes place

29

(excess of water) what is produced?

large amount of dilute urine

30

what other receptors control ADH release?

baroreceptors

31

baroreceptors in the aortic and carotid arteries detect changes in what?

blood pressure which can stimulate or inhibit ADH release

32

(baroreceptors) increase in blood pressure can be caused by a rise in what?

blood vol

33

(baroreceptors) increase in blood pressure is detected by baroreceptors which do what?

prevent release of ADH

34

(baroreceptors) less ADH increases the amount of water lost in urine which has what effect?

reduced blood volume
reduced blood pressure

35

(baroreceptors) what happens if a decrease in blood pressure and vol is detected by baroreceptors?

more ADH released
increased permeability to water
small amount of concentrated urine
increase in blood vol & blood pressure

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