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Biology Chapter 16 (AQA) > 5.3 Kidneys & Osmoregulation > Flashcards

5.3 Kidneys & Osmoregulation Flashcards

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1
Q

what is osmoregulation?

A

controlling water potential of blood within very narrow boundaries

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2
Q

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

A 
salty foods
drinking a lot
exercise
fevers
hot climates
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3
Q

what could happen is kPa was not kept stable?

A

damage or even death

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4
Q

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

A

changing the concentration of urine

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5
Q

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

A

ADH

negative feedback system

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6
Q

ADH is produced by the hypothalamus and secreted where?

A

posterior pituitary where it is stored

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7
Q

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

A

changes their permeability to water

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8
Q

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

A

on cell membrane of tubule cells

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9
Q

when ADH binds it triggers the formation of what?

A

cyclic AMP

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10
Q

Cyclic AMP is a second messenger, what is this?

A

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

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11
Q

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

A

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

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12
Q

membranes of the vesicles contain what?

A

aquaporins

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13
Q

what are aquaporins?

A

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

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14
Q

what do aquaporins provide?

A

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

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15
Q

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

A

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

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16
Q

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

A

kPa

17
Q

what happens when ADH levels fall?

A

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
Q

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

A

osmoreceptors in the hypothalamus

19
Q

what are osmoreceptors sensitive to?

A

the concentrations of inorganic ions in the blood

20
Q

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

A

it becomes more negative

21
Q

(little water) what detects the change in kPa?

A

osmoreceptors

22
Q

(little water) what do the osmoreceptors do?

A

send nerve impulses to posterior pituitary which releases ADH

23
Q

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

A

increases permeability to water

24
Q

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

A

small amount of concentrated urine

25
Q

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

A

less negative

26
Q

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

A

osmoreceptors

27
Q

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

A

reduced or stopped and release of ADH inhibited

28
Q

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

A

remain impermeable to water little reabsorption takes place

29
Q

(excess of water) what is produced?

A

large amount of dilute urine

30
Q

what other receptors control ADH release?

A

baroreceptors

31
Q

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

A

blood pressure which can stimulate or inhibit ADH release

32
Q

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

A

blood vol

33
Q

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

A

prevent release of ADH

34
Q

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

A

reduced blood volume

reduced blood pressure

35
Q

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

A

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

Biology Chapter 16 (AQA) (11 decks)

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