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PSC1002- Physiology > renal system L11-13 > Flashcards

renal system L11-13 Flashcards

1
Q

juxtamedullary nephrons

A

involved in making concentrated urine

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2
Q

no. nephrons per kidney

A

1 million
~80% cortical

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3
Q

renal distribution of blood flow

A

93% cortex
7% medulla
1% papilla

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4
Q

afferent arterioles

A

feed into glomeruli

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5
Q

efferent arterioles

A

leave glomeruli and wrap around nephron

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6
Q

vascular supply to nephrons pathway

A

afferent arterioles > glomeruli> efferent arterioles > peritubular capillaries/ vasa recta> renal veins> inferior vena cava

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7
Q

kidney functions

A

homeostatic regulation of water/ ion content of blood
metabolic waste product excretion
hormone production

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8
Q

hormones produced by kidney

A

erythropoietin (RBC synthesis)
renin (sodium balance)
vit D activation
prostaglandins and kinins (renal blood flow)

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9
Q

what’s filtered at glomerular filtration?

A

all plasma constituents except proteins >67kDa
as filtration barrier filters on size/ charge

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10
Q

glomerular filtration fraction

A

~20%

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11
Q

glomerular filtration rate (GFR)

A

~180 litres/ day

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12
Q

filtration barrier layers surrounding

A

capillary lumen
filtration barrier
capillary endothelium
basement membrane
bowman’s capsule epithelium

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13
Q

pressures controlling glomerular filtration

A

hydrostatic p of blood through glomerular capillaries (~55mmHg)
colloid (30mmHg)
hydrostatic p of fluid in Bowman’s space (15mmHg)

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14
Q

colloid osmotic pressure

A

caused by proteins in blood, favouring fluid retention in capillaries

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15
Q

net glomerular filtration pressure

A

55-30-15=10mmHg

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16
Q

afferent arteriole resistance effect on blood flow to glomerulus

A

^R decreases blood flow
decrease in R ^blood flow

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17
Q

efferent arteriole resistance effect on blood flow to glomerulus

A

^R increases blood flow
decrease in R decreases blood flow

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18
Q

GFR /RBF control

A

maintained relatively constant over range of arterial pressure as a protective mechanism (autoregulation)
neural control
tubuloglomerular feedback

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19
Q

autoregulation local control mechanisms

A

myogenic response
tubuloglomerular feedback (fluid flow influences arteriole resistance/ GFR

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20
Q

why does the nephron loop back in on itself

A

so ascending limb of henle loop passes between afferent/ efferent arterioles

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21
Q

macula densa cells function

A

sense distal tubule flow/ release paracrines that affect afferent arteriole diameter

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22
Q

tubuloglomerular feedback

A

GFR/ tubule flow ^ so ^macula densa flow^ and Na+/Cl- conc sensed
paracrine factors released from macula densa (adenosine/ ATP/ nitric oxide)
afferent constricts and afferent r ^
GFR decrease

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23
Q

urine formation process

A

filtration
reabsorption
secretion (at proximal convoluted tubule)

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24
Q

amount excreted

A

amount filtered - amount reabsorbed + amount excreted

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25
Q

reabsorption

A

movement of solutes/ fluid out of filtrate and into capillaries via epithelial transport mechanisms

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26
Q

epithelial transcellular transport

A

substances cross apical and basolateral membranes of tubule epithelial cells

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27
Q

paracellular transport pathway

A

substances pass through cell-cell junction between 2 adjacent cells

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28
Q

passive transport

A

diffusion (membrane-permeable)
leak channels
paracellular transport

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29
Q

active transport

A

membrane channels
transporters
co-transporters
pumps
carriers

30
Q

PCT functions

A

reabsorption (microvilli on apical surface maximise sa)
secretion
interdigitations of basolateral membrane shorten distance to mitochondria for active transport

31
Q

Na+ reabsorption at PCT-1

A

Passive at apical membrane (down echem gradient)
co-transport w essential solutes

32
Q

water reabsorption at PCT-1

A

paracellular route via osmosis

33
Q

ion reabsorption

A

paracellular/ transcellular along echem gradient

34
Q

glucose at PCT-2

A

co-transport at apical membrane and carrier at basolateral membrane

35
Q

urate at PCT2

A

anion transporters/ paracellular/ passive/ transcellular/ secretion

36
Q

Tm

A

max transport rate

37
Q

renal threshold

A

plasma conc of substrate at Tm

38
Q

diabetes mellitus

A

excessive glucose conc saturates carrier no. and therefore appears in urine

39
Q

PCT secretion

A

peritubular capillary transfer to tubule actively
isosmotic fluid leaving (300mOsm)

40
Q

nephron osmolarity changes

A

descending limb ^ conc (permeable to water/ impermeabe to ions)
ascending limb > hypoosmotic fluid (impermeable water)

41
Q

H2O reabsorption in urine formation

A

ADH^ collecting duct permeability to water
countercurrent systems maintain osmotic gradient in medullary interstitium

42
Q

urine formation countercurrent system multiplier

A

enhanced by active transport of solutes maintaining osmotic gradient

43
Q

acidosis in renal adjustment

A

A intercalated cells in collecting ducts excrete H+ and reabsorb HCO3-

44
Q

alkalosis in renal adjustment

A

B intercalated cells in collecting duct excrete HCO3- and reabsorb H+

45
Q

diuresis

A

removal of excess water from urine

46
Q

what controls permeability in collecting duct?

A

vasopressin
ADH
reabsorption passivelycvia osmotic gradient in medullary interstitium

47
Q

ADH cellular action

A
  1. binds to basolateral membrane receptor
  2. adenlyl cyclase stimulation > cAMP generation and protein kinase activation
  3. aquaporin 2 insertion into apical membrane
  4. ^ permeability
48
Q

ADH release control

A

osmoreceptors

49
Q

ADH release

A

produced by cells in supraopitc/ paraventricular nuclei of hypothalamus
stored in vesicles in p pituitary gland

50
Q

normal plasma osmolarity

A

~290mOsm

51
Q

ADH half-life/ removal

A

~15 mins
removed by liver and kidneys

52
Q

physio ADH release stimuli

A

stress
high temp
exercise
pain

53
Q

alcohol effect on ADH release

A

inhibits

54
Q

inappropriate ADH release stimuli

A

post-operative pain
intracranial disease/ injury
ectopic ADH production
opiates
MDMA/ nicotine
pneumonia/ TB

55
Q

nocturnal enuresis

A

delay in normal circadian rhythm of ADH development

56
Q

MdMa effect on body

A

^ thirst reflex/ ADH secretion/ circulatin g volume
hyponatraemia

57
Q

diabetes insipidus

A

polyuria
ADH secretion deficiency
nephrogenic diabetes insipidus (nephrons don’t respond to ADH)

58
Q

Na+ reabsorption

A

free filtration at glomerulus
~67% PCT reabsorption
none from henle thin ~35% from thick

59
Q

renin-angiotensin-aldosterone axis

A

renin release from kidney
stimulates angiotensin> angiotensin I> angiotensin II> aldosterone> ^Na+rebasorption/ extracellular fluid

60
Q

renin release

A

stretch receptors in afferent arteriole sense low BP and NaCl at macula densa
^renal symp nerve stimulation

61
Q

aldosterone cellular action

A

binds to cytoplasm receptors and initiates txn
^ENaC channels in apical surface
^Na+/Cl- pumps
^Na+ reabsorption (^Cl- and K+ secretion)

62
Q

aldosterone production

A

steroid hormone synthesis in adrenal cortex

63
Q

aldosterone function

A

stimulates angiotensin II
promotes Na+ reabsorption promotion via principle cells in final third of DCT/ Cortical collecting duct
^ blood vol and decreases NaCl/water excretion

64
Q

angiotensin II function

A

stimulates aldosterone release from adrenal cortex
^thirst/ vasoconstriction
^norepinephrine release from symp postganglionic fibres

65
Q

atrial natriuretic peptide

A

produced by atria in response to stretch
regulates plasma vol

66
Q

nephrolithiasis symptoms

A

nausea
renal colic
sweating
blood in urine

67
Q

nephrolithiasis

A

renal calculi formation due to build up of ion/solute conc in filtrate in nephron loop/ distal tube/ collecting system

68
Q

risk factors of nephrolithiasis

A

dehydration
obesity
diet

69
Q

micturition

A

emptying urine from urinary bladder
* up to 500ml

70
Q

2 sphincter muscle rings

A

internal (smooth muscle)
external (skeletal muscle controlled by somatic motor)
neurones/tonic CNS stimulation maintains contraction

71
Q

micturition process

A

stretch receptors fire
para neurones fire and motor stop firing
smooth muscle contracts/ internal sphincter passively pulled open, external sphincter relaxes

PSC1002- Physiology (8 decks)

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