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Flashcards in KIDNEY Deck (48)
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1

which structures make up the renal corpuscle?

glomerular tuft
bowmans capsule

2

what is the glomerular tuft?

convoluted, interconnected glomerular capillaries protruding into the bowmans capsule

3

what are mesangial cells?

specialised pericytes

4

what are the functions of the renal corpuscle?

- structural support for the capillary
- production of extracellular matrix protein
- contraction to regulate flow (tubuloglomerular feedback)
phagocytosis of breakdown products

5

what is the most proximal part of the urinary tract?

bowmans capsule

6

what is the total glomerular surface area?

1m2

7

what are the properties of the membranes in the renal corpuscle?

fenestrated
negatively charged membrane - repels proteins

8

what is the parietal layer of the renal corpuscle membrane?

the bowmans capsule - 2 layers
(parietal cells and basement membrane)

9

what is the visceral layer of the renal corpuscle membrane?

the glomerulus - 3 layers
(endothelial cells, basement membrane, podocytes)

10

what is the structure of the endothelial cells in the glomerulus?

fenestrated
single cell thick

11

what is the structure of the basement membrane in the glomerulus?

it is the fusion of 2 basement membranes
the capillary and podocyte basement membranes fuse
it is negatively charged

12

what is the structure of glomerular podocytes?

single cell layer
they have a large number of interdigitating foot processes which act as a filtrate barrier
each podocyte is in contact with multiple cells

13

what are the 2 methods of autoregulation in the kidney?

myogenic
tubuloglomerular feedback

14

what happens in myogenic autoregulation in the kidney?

smooth muscle contraction in response to external stretching force
it occurs in capillary walls
it is a passive mechanism

15

what happens in tubuloglomerular feedback in autoregulation in the kidney?

there is constriction of afferent arteriole to increased sodium chloride concentration
dilation in response to decreased concentration
fast response = GFR
slow response = RAAS

16

what is the role of macula densa cells in tubuloglomerular feedback?

they detect Na+ concentration levels through NKCC2 transporter
this signals through adenosine and nitric oxide to walls of arterioles

17

which arterioles are affected by the tubuloglomerular feedback?

afferent

18

what happens in the tubuloglomerular feedback system?

macula densa cells detect Na+ concentration levels through NKCC2 transporter
this signals through adenosine and nitric oxide to walls of arterioles
if flow rate is low = dilation of afferent arteriole
if flow rate is high = constriction of afferent arteriole

19

what is the action of the tubuloglomerular feedback if flow is low?

dilation of afferent arteriole

20

what is the action of the tubuloglomerular feedback if flow is high?

constriction of afferent arteriole

21

what is the effect of sympathetic activity on tubuloglomerular feedback?

a reduced GFR and renal blood flow increases sympathetic activity
this cause vasoconstriction of afferent arteriole
this increases heart rate, BP and cardiac output
this tries to shunt blood to muscles

22

what happens to increase GFR?

constrict efferent arteriole
dilate afferent arteriole

23

what happens to decrease GFR?

dilates efferent arteriole
constricts afferent arteriole

24

what is the general state of renal perfusion and when does it fail?

it is generally stable
fails above 200mmHg and below 80mmHg

25

what is glomerular filtration?

it is the passage of fluid from the blood into bowmans space

26

what is glomerular filtration determined by?

- pressure gradients
- the size of the molecule
- charge of the molecule
- rate of blood flow
- surface area
- binding to plasma proteins

27

what is the normal GFR?

125ml / min

28

in an average 70Kg person, how much plasma passes through the glomerulus?

roughly 20%

29

what is used to measure GFR?

creatinine

30

what are the requirements for using a substance to measure GFR?

- must be freely filtered by glomerulus
- not secreted or absorbed in tubules
- not metabolised
- constantly produced as a muscle metabolite
- amount depends on muscle mass