5.1.2 (c) the Kidney Flashcards

1
Q

what 2 homeostatic roles do the kidneys play in the body?

A

excretion
osmoregulation

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2
Q

how are the kidneys involved in excretion?

A

they filter nitrogenous waste out of the blood

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3
Q

how are the kidneys involved in osmoregulation?

A

by helping maintain water balance and the pH of the blood

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4
Q

what vessel carries blood into the kidneys?

A

the renal arteries which branch off of the aorta

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5
Q

which vessel carries blood out of the kidneys?

A

renal vein which drains into the vena cava

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6
Q

what are the kidneys composed of?

A

nephrons which are filtering units

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7
Q

what liquid is produced by the kidney tubules?

A

urine

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8
Q

what does the urine leave the kidney in?

A

the ureter

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9
Q

what does the ureter lead to?

A

the bladder

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10
Q

how does urine leave the bladder?

A

through the urethra and out of the body

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11
Q

what are the 3 main areas of the kidney?

A

cortex
medulla
pelvis

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12
Q

what happens in the kidney cortex?

A

site of ultrafiltration

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13
Q

what happens in the kidney medulla?

A

selective reabsorption and osmoregulation

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14
Q

what happens in the kidney pelvis?

A

where the urine collects and then passed into the ureter

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15
Q

what are the 5 regions of a nephron?

A

bowman’s capsule
proximal convoluted tubule
loop of Henle
distal convoluted tubule
collecting duct

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16
Q

what is the bowman’s capsule?

A

contains the glomerulus which is where ultrafiltration takes place

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17
Q

what is the proximal convoluted tubule?

A

coiled region following the bowman’s capsule where selective reabsorption begins

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18
Q

what is the loop of Henle?

A

long loop with an ascending and descending loop where selective reabsorption takes place

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19
Q

what is the distal convoluted tubule?

A

second coiled region following the loop of Henle where osmoregulation occurs with its wall’s permeability affected by ADH levels

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20
Q

what is the collecting duct?

A

moves urine down the medulla and into the pelvis as well as more osmoregulation

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21
Q

what are the 3 functions of the nephrons?

A

ultrafiltration
selective reabsorption
osmoregulation

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22
Q

what supplies the glomerulus with blood?

A

afferent arteriole

23
Q

what forces blood out through the capillary walls of the glomerulus?

A

the greater pressure created by the efferent arteriole

blood moves from a high pressure to a low pressure through fenestrations in the glomerulus

24
Q

what does the blood leave the glomerulus in?

A

efferent arteriole

which is narrower and therefore creates greater pressure

25
Q

what are the three layers between the capillary and Bowman’s capsule?

A

capillary endothelium
basement membrane
podocytes

26
Q

what are found in the capillary endothelium to control entry of blood?

A

fenestrations to prevent large molecules from passing through

27
Q

what is the basement membrane?

A

acts as a second sieve by filtering out the plasma contents

28
Q

what cannot pass through the basement membrane and why?

A

plasma proteins and red blood cells

they are both too large to fit through…

29
Q

what effect does the plasma proteins remaining in the blood have on the capillaries?

A

this creates a low water potential which allows for water to move back into the blood later

30
Q

what are podocytes?

A

specialised cells which wrap around the capillaries and form slits to prevent large molecules from passing through

31
Q

what do podocytes filter out?

A

any cells, platelets or large plasma proteins which have managed to get through the epithelial and basement membrane

32
Q

order of 3 part filter

A

glomerulus endothelium
basement membrane
podocytes

33
Q

what does the filtrate after the bowman’s capsule contain?

A

salt
glucose
urea
water

34
Q

why does selective reabsorption occur?

A

to bring back necessary substances which have been removed from the blood, back into the blood

35
Q

where does selective reabsorption occur?

A

at the proximal convoluted tubule

36
Q

what is reabsorbed at the proximal convoluted tubule?

A

sodium chloride
water

glucose
amino acids

37
Q

how are glucose and amino acids removed from the filtrate at the proximal convoluted tubule?

A

by active transport

38
Q

how are sodium ions removed from the filtrate at the proximal convoluted tubule?

A

pumped out by active transport

39
Q

how are chloride ions and water removed from the filtrate at the proximal convoluted tubule?

A

passively down a concentration gradient

40
Q

what are the adaptations of the proximal convoluted tubule?

A
  • covered with microvilli which increase the SA so more substances can be reabsorbed
  • have many mitochondria to provide ATP for active transport
  • epithelium lines walls
41
Q

where do the reabsorbed materials go after being reabsorbed?

A

they diffuse into extensive capillary network which has a steep concentration gradient between them which is maintained by a constant flow of blood

42
Q

what does Loop of Henle act as?

A

acts as a countercurrent multiplier by using energy to produce a concentration gradient that allows for the movement of substances

43
Q

what happens to Na+ and Cl- ions in the descending loop?

A

they stay in the filtrate as the walls are impermeable to Na+ and Cl-

makes the filtrate very concentrated

44
Q

what happens to Na+ and Cl- in the ascending limb?

A

Na+ and Cl- ions are pumped out into the medulla at the top

Na+ and Cl- ions diffuse into the medulla at the bottom

this makes the water potential in the medulla lower

filtrate leaves very dilute

45
Q

as the water potential of the medulla is lower what happens at the top of the descending limb?

A

water moves into the medulla by osmosis from high water potential to low water potential

water is reabsorbed into the blood via capillaries

46
Q

as the water potential of the medulla is lower what happens to the collecting duct?

A

water moves out by osmosis and then reabsorbed into the blood via capillaries

47
Q

what stops water and ions re-entering the Loop of Henle at the ascending loop?

A

it is impermeable to water

48
Q

what is the role of the distal convoluted tubule?

A

site of water balancing
controls the pH levels

49
Q

what hormone are the walls of the DCT affected by?

A

ADH

50
Q

what organelle is found in excess in the DCT and why?

A

contain a lot of mitochondria to power active transport

51
Q

what is pumped out of the filtrate at the DCT when salt conc is low?

A

Na+ ions and Cl- ions are actively pumped back into the blood to restore salt conc

52
Q

what is the function of the collecting duct?

A

more osmoregulation
walls effected by ADH
water moves out by diffusion

53
Q

why cant podocytes underogo mitosis?

A

they are specialised so remain in G0
therefore formation of spindle fibres and mitosis cannot occur

54
Q

features of glomerulus

A

efferent arteriole more narrower than afferent
causes a high hydrostatic pressure
forces filtrate to form in bowman’s capsule

fenestrations in the endothelium are small
prevent large plasma proteins and RBCs from entering