L2: Glomerular structure and function Flashcards
1
Q
hilum of the kidney=
A
where blood vessels come in and ureter comes out
2
Q
2 main parts of the kidney
A
cortex and medulla
3
Q
what is in the medulla
A
renal pyramids
4
Q
how many renal pyramids
A
8-18
5
Q
where do the renal pyramids drain into
A
major calyxes
6
Q
where are the renal pyramids found
A
border between medulla and cortex
7
Q
what arteries supply the kidneys
A
renal arteries
8
Q
renal arteries branch into
A
inter-lobar arteries
9
Q
inter-lobar arteries branch into
A
arcuate arteries
10
Q
arcuate arteries branch into
A
interlobular arteries
11
Q
what do interlobular arteries form
A
afferent arterioles
12
Q
what do afferent arterioles branch into
A
glomerular capillaries
13
Q
what do glomerular capillaries form
A
efferent arterioles
14
Q
what blood supply does each nephron receive
A
one afferent arteriole
15
Q
what do the efferent arteries in the cortex form
A
peritubular capillaries
16
Q
what arteries may extend down from the efferent arteries
A
vasa recta
17
Q
what do vasa recta supply
A
tubular portions of the nephron in the renal medulla
18
Q
which part of the kidney has the best blood supply
A
the cortex
19
Q
what does a nephron consist of
A
renal corpuscle and tubules
20
Q
what does the renal corpuscle consist of
A
glomerulus surrounded by bowman’s capsule
21
Q
what is the glomerulus
A
a tuft of capillaries
22
Q
6 parts of the kidney tubule
A
- proximal kidney tubule
- thin descending loop
- thin ascending loop
- thick ascending loop
- distal convoluted tubule
- collecting tubule
23
Q
histology of the proximal kidney tubule=
A
- cuboidal cells and microvilli + lots of mitochondria
- basolateral membrane has tight junctions
24
Q
where is urine formed
A
renal pelvis
25
2 types of nephrons
1. cortical/ superficial nephron
| 2. juxta-medullary nephron
26
where are cortical/ superficial nephrons found
mainly in the cortex (very short loop of henle)
27
percentage of juxta-medullary nephrons
15%
28
what do cortical nephrons receive a blood supply from
peritubular capillaries
29
what do juxtamedullar nephrons receive a blood supply from
vasa recta
30
histology of thin descending and ascending loops
simple squamous
31
histology of thick ascending loop
simple cuboidal to low columnar
32
histology of DCT
- simply cuboidal
| - and later on get principal and intercalated cells
33
what do principal cells have receptors for
ADH and aldosterone
34
what do intercalated cells do
homeostasis of blood pH
35
what is the first step in the urine production
glomerular filtration
36
what happens in glomerular filtration
water and most solutes in blood plasma move across from the capillaries into the glomerular capsule and into the renal tubule
37
what are glomerular capillaries impermeable to
proteins
38
what type of capillaries are the glomerular ones
fenestrated
39
3 things the capillaries are made up off
endothelium
basement membrane
podocytes
40
what is the charge of the basement membrane
negative charge
41
what is the juxtaglomerular apparatus comprised of (3)
- granular cells
- Macula densa
- extraglomerular mesangial cells
42
where are the granular cells in the JGA
in afferent arterioles walls
43
what are the granular cells
- modified smooth muscle cells that contain renin
| - innervated by sympathetic NS
44
where are the macula densa found in the JGA
where the DCT comes into contact with afferent and efferent arterioles
45
what is the role of the JGA
to synthesise and store renin
46
3 things glomerular filtration is based on
surface area
membrane permeability
net filtration pressure
47
what is the glomerular capillary pressure
pressure of blood entering the afferent arteriole drives fluid across filtration barrier
48
what opposes the glomerular capillary pressure
fluid in Bowman's space (hydrostatic pressure)
49
what other pressure is caused by the Bowman's space
weak osmotic pressure
50
what does Bowman's space weak osmotic pressure cause
forces fluid out from blood
51
what exerts the plasma oncotic pressure
plasma proteins
52
how much urine production a day in normal
1-2 litres
53
Kf=
ultrafiltration coefficient
54
Puf=
net filtration pressure
55
what is Kf a product of
permeability of membrane and surface area
56
the filtration of a solute depends on 3 things
- molecular size
- electrical charge
- shape of the molecule
57
how come albumin cannot cross
negatively charged so basement membrane repels it
58
renal blood flow= (equation)
renal artery pressure - renal vein pressure
| / total renal vascular resistance
59
which arteries offer maximum resistance
efferent arterioles
60
why do efferent arterioles offer maximum resistance
they are much smaller in comparison to afferent
61
what is different about capillaries in the kidney vs rest of the body
main high pressure all the way through the capillary
62
what is autoregulation between
80-180mmHg
63
afferent arteriolar dilation affect on GFR=
increases GFR
64
efferent arteriolar dilation effect on GFR=
decreases GFR
65
afferent arteriolar constriction affect on GFR=
fall in GFR (and hydrostatic pressure)
66
efferent arteriolar constriction on GFR=
increase GFR
67
what is the effect on the afferent arterioles with Ang 2, Noradrenaline, Endothelin and ADH
vasoconstriction--> decrease in GFR
68
2 mechanisms involved in autoregulation
myogenic mechanism
| tubuloglomerular feedback
69
myogenic mechanism for high BP =
- 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
in shock/ haemorrhage what happens with myogenic mechanism
sympathetic vasoconstriction of afferent arterioles decrease GFR
71
tubuloglomerular feedback uses which cells
macular densa in JGA
72
what is tubuloglomerular feedback when GFR is increased
- 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
what do macula densa act as a sensor of
sodium
74
where is renin released from
JGA
75
when is renin released from JGA
decreased blood pressure
76
what cells release renin
granular cells
77
what does renin do
converts angiotensinogen into angiotensin 1
78
what happens to angiotensin 1
is converted to angiotensin 2 in the lungs by ACE
79
what is angiotensin 2 affect on systemic arteries
vasoconstriction increasing Blood pressure
80
what is Ang 2 affect on adrenal cortex
releases aldosterone
81
what affect does aldosterone have on the kidneys
-increases reabsorption of sodium and water by the kidneys (more concentrated urine)
82
what does aldosterone stimulate the release off from the pituitary gland
ADH
83
what does ADH do
stimulates pituitary gland to secrete ADH
84
affect of increased sympathetic activity on GFR=
decrease GFR
85
affect of angiotensin 2 on GFR
decrease GFR
86
affect of atrial natriuretic peptide on GFR
increase
87
name 2 invasive techniques for measuring GFR
1. inulin or isothalamate clearance
| 2. chromium labelled EDTA
88
4 problems with using serum creatinine for GFR
- actively secreted by tubules
- insensitive as marker for early kidney disease
- affected by muscle mass
- affected by certain drugs
89
MDRD=
modification of diet in renal disease
90
what does MDRD use to estimate eGFR
serum creatinine, age, sex, ethnicity
