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Biology A2 > Organisms Response to Change - Kidneys > Flashcards

Organisms Response to Change - Kidneys Flashcards

1
Q

what are the roles of the kidneys?

A

osmoregulation

excretion

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2
Q

how do the kidneys carry out osmoregulation?

A

by controlling the volume and concentration of urine produced

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3
Q

how do the kidneys carry out excretion?

A

by removing waste products from the metabolism

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4
Q

what is a nephron?

A

the functional unit of a kidney

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5
Q

what is the fibrous capsule?

A

the outer membrane that protects the kidney

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6
Q

what is the cortex?

A

the lighter coloured outer region consisting of renal capsules, convulated tubules and blood vessels

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7
Q

what is the medulla?

A

darker coloured inner region of the kidney consisting of the loops of henle, collecting ducts and blood vessels

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8
Q

what is the renal pelvis?

A

a funnel-shaped cavity that collects urine into the ureter

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9
Q

what is the ureter?

A

a tube that carries urine to the bladder

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10
Q

what is the renal artery?

A

the artery that supplies the kidney with blood

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11
Q

what is the renal vein?

A

the vein that returns blood to the heart from the kidney

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12
Q

what are the main components of a nephron?

A

renal capsule

proximal convulated tubule

loop of henle

distal convulated tubule

collecting duct

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13
Q

what is the renal capsule?

A

closed end at the start of the nephron

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14
Q

what is the structure of the renal capsule?

A

cup-shaped and surrounds the glomerulus

inner layer consists of podocytes - specialised cells

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15
Q

what is the proximal convulated tubule?

A

series of loops surrounded by blood capillaries

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16
Q

what is the structure of proximal convulated tubule?

A

walls consist of epithelial cells containing microvilli

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17
Q

what is the loop of henle?

A

long, hairpin loop extending from the cortex into the medulla and back again

surrounded by blood capillaries

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18
Q

what is the distal convulated tubule?

A

series of loops surrounded by blood capillaries, but less than proximal convulated tubule

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19
Q

what is the collecting duct?

A

tube that distal convulated tubules empty into

becomes increasingly wide as it empties into pelvis of kidney

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20
Q

what is the structure of the collecting duct?

A

lined with epithelial cells

becomes wider as it empties into pelvis of the kidney

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21
Q

what are the different blood vessels present in a nephron?

A

afferent and efferent arterioles

glomerulus

blood capillaries

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22
Q

what is the afferent arteriole?

A

vessel from the renal artery that supplies the nephron and glomerulus with blood

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23
Q

what is the glomerulus?

A

branched knot of capillaries between the afferent and efferent arterioles

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24
Q

what is the efferent arteriole?

A

blood vessel attached to the glomerulus, carrying blood away from the renal capsule

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25
Q

describe the blood capillaries present in a nephron

A

concentrated network surrounding:

distal/proximated convulated tubules

loop of henle

they merge to form the renal vein

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26
Q

what are the 2 processes involved in the production of urine?

A

ultrafiltration

selective readsorption

27
Q

label this diagram of a nephron

A

A - afferent arteriole

B - glomerulus

C - efferent arteriole

D - distal convulated tubule

E - renal capsule

F - proximal convulated tubule

G - ascending loop of henle

H - descending loop of henle

I - collecting duct

28
Q

describe the process of ultrafiltration

A

high pressure created in glomerulus

water and small molecules are forced out of the blood and into renal capsule

29
Q

how is a high pressure created in the glomerulus?

A

efferent arteriole has a narrower diameter than the afferent arteriole

coiling of capillaries in the glomerulus restricts blood flow

30
Q

what is the pathway for filtration in the renal capsule?

A

glomerular capillary endothelium

basement membrane

renal capsule epithelium / podocytes

31
Q

what components of the filtrate cannot pass through the glomerular capillary endothelium in ultrafiltration?

A

red blood cells

32
Q

which components of the filtrate cannot pass through the basement membrane in ultrafiltration?

A

plasma proteins

33
Q

which components of the filtrate can pass through the filtration pathway in ultrafiltration?

A

water

glucose

electrolytes

amino acids

fatty acids

nitrogenous wastes

34
Q

what components of the nephron are involved in selective readsorption?

A

proximal convulated tubule

loop of henle

distal convulated tubule

collecting duct

35
Q

how much of the filtrate is readsorbed in the proximal convulated tubule?

A

85%

36
Q

what is the role of the loop of henle in selective readsorption?

A

allows water to be readsorbed from collecting duct

37
Q

what is the role of the distal convulated tubule in selective readsorption?

A

makes final adjustments

toxic substances are secreted into the filtrate

water readsorption

38
Q

what is the role of the collecting duct in selective readsorption?

A

water readsorption

39
Q

what is readsorbed in the proximal convulated tubule?

A

water

ions

glucose

amino acids + small proteins

urea

40
Q

which substances are readsorbed through facilitated diffusion / active transport in the PCT?

A

ions

glucose

amino acids

41
Q

how is water readsorbed in the PCT?

A

osmosis

42
Q

how is urea readsorbed in the PCT?

A

passively due to the movement of water by osmosis

43
Q

what are the adaptations of the PCT for selective readsorption?

A

microvilli and infoldings to increase surface area

mitochondria for active transport/facilitated diffusion

44
Q

which substances are readsorbed by co-transport in the PCT?

A

glucose

amino acids

45
Q

describe how glucose and amino acids are readsorbed by co-transport in the PCT

A
  1. Na+ actively transported from PCT into blood and are carried away
  2. Na+ diffuse into PCT cells from lumen of PCT by facilitated diffusion
  3. glucose or amino acid carried with the ion
  4. glucose/amino acid and Na+ then diffuses into blood from PCT
46
Q

what % of water and ions have been readsorbed at the end of the proximal convulated tubule?

A

65%

47
Q

what % of glucose and amino acids have been readsorbed at the end of the proximal convulated tubule?

A

100%

48
Q

what change is there to the concentration of urea at the end of the proximal convulated tubule?

A

conc will have increased

49
Q

how does the loop of henle allow water to be readsorbed in the collecting duct?

A

makes the medulla concentrated with ions, lowering water potential, promoting readsorption by osmosis

50
Q

why is the water potential high at the start of the loop of henle?

A

all of the glucose and amino acids were readsorbed in the PCT so the filtrate is less concentrated

51
Q

what are the 2 regions of the loop of henle?

A

descending limb

ascending limb

52
Q

what are the differences between the descending and ascending limbs of the loop of henle?

A

descending: narrow, thin walls that are highly permeable to water
ascending: wider, thick walls impermeable to water

53
Q

describe what happens in the descending limb of the loop of henle

A

water potential lowered so water diffuses out of descending limb and into blood capillaries

filtrate moves along descending limb, becoming more concentrated

54
Q

how is the water potential lowered in the descending limb of the loop of henle?

A

Na+ actively transported out of ascending limb, some passively diffuse into the descending limb, but most accumulate in interstitial region

55
Q

what is the interstitial region?

A

region between the cortex and medulla of the kidney

56
Q

describe what happens in the ascending limb of the loop of henle

A

at bottom of the limb - sodium ions diffuse out

as filtrate moves along limb, sodium ions actively transported out

filtrate becomes less concentrated and water potential increases

57
Q

what is the countercurrent multiplier?

A

filtrate in collecting duct with a low water potential meets interstitial fluid with lower water potential

ensures water potential gradient exists for entire length of collecting duct

58
Q

where is ADH produced?

A

hypothalamus

59
Q

where is ADH stored and secreted from?

A

posterior pituitary

60
Q

how does the hypothalamus detect low water potential in the blood?

A

osmoreceptors in the hypothalamus shrink

61
Q

describe what happens when low water potential is detected in the hypothalamus

A

impulses sent to posterior pituitary

ADH released into blood and travels to kidneys

62
Q

how does ADH cause the kidneys to change the water potential of the blood?

A

ADH binds to receptors of distal convulated tubule and collecting duct, activating phosphorlyase

phosphorylase causes vesicles in the cells to move and fuse will cell membrane, inserting aquaporins into the membrane

permeability to water + urea of collecting duct increased

more water passes into medulla fluid and blood vessels

urea passes into medulla fluid, lowering water potential

63
Q

how do osmoreceptors respond to thirst?

A

impulses sent to thirst centre of the brain increasing intake of water

64
Q
A

Biology A2 (15 decks)

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