lecture 18 Flashcards

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1
Q

what are the four main functions of the excretory system

A
  1. regulate volume of the fluid in the body 2. maintain individual solutes (CA2+, NA+, H+) at appropriate concentrations 3. regulate solute concentration in extracellular fluid (osmolarity) 4. eliminate nitrogenous waste
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2
Q

an excretory systems ability to change ECF composition depends on

A

its ability to make a dilute or concentrate urine

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3
Q

ALL vertebrates can make a urine

A

less concentrated than the ECF, therefore concentrate the ECF (U/P<1)

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4
Q

kidneys of mammals and birds ONLY can also make urine

A

more concentrated urine than the ECF there fore can dilute the ECF via the kidneys (U/P>1)

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5
Q

what does u/p = 1 mean

A

150 mM, no net ECF concentration change, what you put in is what you take out

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6
Q

what does u/p > 1 mean

A

300 -> 150 mM ECF conc is decreased, more salt less water so you get rid of salt and keep h20

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7
Q

what does u/p < 1 mean

A

50 -> 150 mM ECF conc is increased water is more salt is less, you take out water and keep salt

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8
Q

what does the U and P stand for

A

urine and plasma

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9
Q

what i the functional unit of kidneys

A

nephrons

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10
Q

what do nephrons consist of

A

renal tubules and surrounding blood vessels

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11
Q

how is urine produced

A

by filtering blood plasma

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12
Q

where does ultrafiltration occur

A

glomerulus

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13
Q

after ultrafiltration, where does the plasma go

A

water and solutes are pushed into BOWMANS capsule by blood pressure

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14
Q

what do renal tubules do

A

they selectively secrete and reabsorb solutes and water to form urine

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15
Q

what do the proximal segments of vertebrate tubules do

A

they reabsorb salt water and nutrients back into blood while leaving toxins in the tubules

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16
Q

terrestrial animals that drink a lot of fresh water must produce

A

lots of volumes of dilute urine

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17
Q

the late tubules of ALL vertebrates can make urine with what ratio

A

u/p <1

18
Q

diuresis

A

a state in which dilute urine is made to eliminate excess water and conserve salts

19
Q

where does diuresis and antidiuresis occur

A

the distal/late tubules

20
Q

in diuresis what happens in the kidneys

A

osmosis of water doesnt happen (means that water isnt reabsorbed) but active trasport of NaCI yes!

21
Q

vertebrates in dry environments must conserve water by

A

producing very little urine that as very concentrated

22
Q

the most concentrated urine that fish and amphibians can make is

A

u/p is equal to one

23
Q

antidiuresis

A

the state in which concentrated urine is made to conserve water

24
Q

how is antidiuresis achieved

A

by increasing water permeability (osmosis of water) in the distal tubules

25
Q

distal tubules can add or remove what

A

water channels of aquaporins to become more or less permeable to water

26
Q

what hormone regulated these aquaporins

A

ADH or antidiuretic hormone

27
Q

why does body do all of this renal stuff

A

homeostasis

28
Q

ADH is how we regulate

A

water and salt levels in our bodies

29
Q

what kind of feedback is this renal stuff

A

negative

30
Q

what happens if water level drops

A

ADH is released and kidneys absorb more water

31
Q

what happens if water level rises

A

ADH is released less and kidneys reabsorb less water

32
Q

diuresis has

A

low ADH so few aquaporins, dilute urine u/p<1

33
Q

antidiuresis has

A

high ADH so more aquaporins , more conc urin u/p=1

34
Q

how do mammals and birds get a u/p>1 4 steps

A

1.they use the loop of henle to create a concentration gradient in the medulla of the kidney 2.the collecting ducts pass through tissue that is increasingly high conc 4. resulting urine is more conc than plasma

35
Q

what is the toxic byproduct of amino acid and protein metabolism

A

ammonia

36
Q

what do fish do with ammonia

A

they have a bunch of water to dissolve it in so they keep the ammonia

37
Q

what do mammals do with ammonia

A

they change it to urea

38
Q

what do reptiles and birds do with ammonia

A

they change it to uric acid

39
Q

what nitrogenous compounds are more energetically costly (most to less)

A

uric acid, urea, and ammonia

40
Q

what nitrogenous compounds need more water (most to less)

A

ammonia, urea, uric acid

41
Q

urine that exits the proximal tubules is

A

lower volume and same conc as plasma

42
Q

urine that exits distal tubules is

A

influenced by homeostatic mechanisms to be more dilute or conc