L2: Glomerular structure and function Flashcards

1
Q

hilum of the kidney=

A

where blood vessels come in and ureter comes out

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2
Q

2 main parts of the kidney

A

cortex and medulla

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3
Q

what is in the medulla

A

renal pyramids

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4
Q

how many renal pyramids

A

8-18

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5
Q

where do the renal pyramids drain into

A

major calyxes

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6
Q

where are the renal pyramids found

A

border between medulla and cortex

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7
Q

what arteries supply the kidneys

A

renal arteries

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8
Q

renal arteries branch into

A

inter-lobar arteries

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9
Q

inter-lobar arteries branch into

A

arcuate arteries

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10
Q

arcuate arteries branch into

A

interlobular arteries

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11
Q

what do interlobular arteries form

A

afferent arterioles

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12
Q

what do afferent arterioles branch into

A

glomerular capillaries

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13
Q

what do glomerular capillaries form

A

efferent arterioles

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14
Q

what blood supply does each nephron receive

A

one afferent arteriole

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15
Q

what do the efferent arteries in the cortex form

A

peritubular capillaries

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16
Q

what arteries may extend down from the efferent arteries

A

vasa recta

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17
Q

what do vasa recta supply

A

tubular portions of the nephron in the renal medulla

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18
Q

which part of the kidney has the best blood supply

A

the cortex

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19
Q

what does a nephron consist of

A

renal corpuscle and tubules

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20
Q

what does the renal corpuscle consist of

A

glomerulus surrounded by bowman’s capsule

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21
Q

what is the glomerulus

A

a tuft of capillaries

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22
Q

6 parts of the kidney tubule

A
  1. proximal kidney tubule
  2. thin descending loop
  3. thin ascending loop
  4. thick ascending loop
  5. distal convoluted tubule
  6. collecting tubule
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23
Q

histology of the proximal kidney tubule=

A
  • cuboidal cells and microvilli + lots of mitochondria

- basolateral membrane has tight junctions

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24
Q

where is urine formed

A

renal pelvis

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25
Q

2 types of nephrons

A
  1. cortical/ superficial nephron

2. juxta-medullary nephron

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26
Q

where are cortical/ superficial nephrons found

A

mainly in the cortex (very short loop of henle)

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27
Q

percentage of juxta-medullary nephrons

A

15%

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28
Q

what do cortical nephrons receive a blood supply from

A

peritubular capillaries

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29
Q

what do juxtamedullar nephrons receive a blood supply from

A

vasa recta

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30
Q

histology of thin descending and ascending loops

A

simple squamous

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31
Q

histology of thick ascending loop

A

simple cuboidal to low columnar

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32
Q

histology of DCT

A
  • simply cuboidal

- and later on get principal and intercalated cells

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33
Q

what do principal cells have receptors for

A

ADH and aldosterone

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34
Q

what do intercalated cells do

A

homeostasis of blood pH

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35
Q

what is the first step in the urine production

A

glomerular filtration

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36
Q

what happens in glomerular filtration

A

water and most solutes in blood plasma move across from the capillaries into the glomerular capsule and into the renal tubule

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37
Q

what are glomerular capillaries impermeable to

A

proteins

38
Q

what type of capillaries are the glomerular ones

A

fenestrated

39
Q

3 things the capillaries are made up off

A

endothelium
basement membrane
podocytes

40
Q

what is the charge of the basement membrane

A

negative charge

41
Q

what is the juxtaglomerular apparatus comprised of (3)

A
  • granular cells
  • Macula densa
  • extraglomerular mesangial cells
42
Q

where are the granular cells in the JGA

A

in afferent arterioles walls

43
Q

what are the granular cells

A
  • modified smooth muscle cells that contain renin

- innervated by sympathetic NS

44
Q

where are the macula densa found in the JGA

A

where the DCT comes into contact with afferent and efferent arterioles

45
Q

what is the role of the JGA

A

to synthesise and store renin

46
Q

3 things glomerular filtration is based on

A

surface area
membrane permeability
net filtration pressure

47
Q

what is the glomerular capillary pressure

A

pressure of blood entering the afferent arteriole drives fluid across filtration barrier

48
Q

what opposes the glomerular capillary pressure

A

fluid in Bowman’s space (hydrostatic pressure)

49
Q

what other pressure is caused by the Bowman’s space

A

weak osmotic pressure

50
Q

what does Bowman’s space weak osmotic pressure cause

A

forces fluid out from blood

51
Q

what exerts the plasma oncotic pressure

A

plasma proteins

52
Q

how much urine production a day in normal

A

1-2 litres

53
Q

Kf=

A

ultrafiltration coefficient

54
Q

Puf=

A

net filtration pressure

55
Q

what is Kf a product of

A

permeability of membrane and surface area

56
Q

the filtration of a solute depends on 3 things

A
  • molecular size
  • electrical charge
  • shape of the molecule
57
Q

how come albumin cannot cross

A

negatively charged so basement membrane repels it

58
Q

renal blood flow= (equation)

A

renal artery pressure - renal vein pressure

/ total renal vascular resistance

59
Q

which arteries offer maximum resistance

A

efferent arterioles

60
Q

why do efferent arterioles offer maximum resistance

A

they are much smaller in comparison to afferent

61
Q

what is different about capillaries in the kidney vs rest of the body

A

main high pressure all the way through the capillary

62
Q

what is autoregulation between

A

80-180mmHg

63
Q

afferent arteriolar dilation affect on GFR=

A

increases GFR

64
Q

efferent arteriolar dilation effect on GFR=

A

decreases GFR

65
Q

afferent arteriolar constriction affect on GFR=

A

fall in GFR (and hydrostatic pressure)

66
Q

efferent arteriolar constriction on GFR=

A

increase GFR

67
Q

what is the effect on the afferent arterioles with Ang 2, Noradrenaline, Endothelin and ADH

A

vasoconstriction–> decrease in GFR

68
Q

2 mechanisms involved in autoregulation

A

myogenic mechanism

tubuloglomerular feedback

69
Q

myogenic mechanism for high BP =

A
  • increase Bp
  • stretch of afferent arterioles
  • increased GFR and NFP (net filtration pressure)
  • triggers smooth muscle arteriolar vasoconstriction
  • decrease glomerular Bp
  • decrease NFP
  • decreased filtration
70
Q

in shock/ haemorrhage what happens with myogenic mechanism

A

sympathetic vasoconstriction of afferent arterioles decrease GFR

71
Q

tubuloglomerular feedback uses which cells

A

macular densa in JGA

72
Q

what is tubuloglomerular feedback when GFR is increased

A
  • increased GFR
  • increases tubular fluid flow
  • increases NaCL reabsorbed in macula densa
  • causes vasoconstriction substance (possibly adenosine) released onto JGA
  • vasoconstriction of afferent arteriole
73
Q

what do macula densa act as a sensor of

A

sodium

74
Q

where is renin released from

A

JGA

75
Q

when is renin released from JGA

A

decreased blood pressure

76
Q

what cells release renin

A

granular cells

77
Q

what does renin do

A

converts angiotensinogen into angiotensin 1

78
Q

what happens to angiotensin 1

A

is converted to angiotensin 2 in the lungs by ACE

79
Q

what is angiotensin 2 affect on systemic arteries

A

vasoconstriction increasing Blood pressure

80
Q

what is Ang 2 affect on adrenal cortex

A

releases aldosterone

81
Q

what affect does aldosterone have on the kidneys

A

-increases reabsorption of sodium and water by the kidneys (more concentrated urine)

82
Q

what does aldosterone stimulate the release off from the pituitary gland

A

ADH

83
Q

what does ADH do

A

stimulates pituitary gland to secrete ADH

84
Q

affect of increased sympathetic activity on GFR=

A

decrease GFR

85
Q

affect of angiotensin 2 on GFR

A

decrease GFR

86
Q

affect of atrial natriuretic peptide on GFR

A

increase

87
Q

name 2 invasive techniques for measuring GFR

A
  1. inulin or isothalamate clearance

2. chromium labelled EDTA

88
Q

4 problems with using serum creatinine for GFR

A
  • actively secreted by tubules
  • insensitive as marker for early kidney disease
  • affected by muscle mass
  • affected by certain drugs
89
Q

MDRD=

A

modification of diet in renal disease

90
Q

what does MDRD use to estimate eGFR

A

serum creatinine, age, sex, ethnicity