Renal Mod 1 Flashcards
1
Q
2 capsules of the kidney
A
- renal capsule - surrounds each kidney
2. renal fascia - surrounds kidney and fatty mass
2
Q
list the gross anatomy of the kidneys
A
- capsules
- cortex
- medulla
- renal pyramid
- minor calyces
- major calyces
- renal pelvis
- ureter
3
Q
what does the cortex include
A
- glomeruli
2. proximal and distal portions of tubules
4
Q
what is the medulla of the kidneys
A
straight segments of proximal and distal tubules
5
Q
what is the renal pyramid
A
functional arrangement for collection
-includes the renal papilla
6
Q
what is the renal papilla
A
the apex of the pyramid which drains into the minor calyces
7
Q
what are minor calyces
A
collect urine from renal pyramids
8
Q
what are the major calyces
A
collect urine from 2-3 minor calyces
9
Q
what is the renal pelvis
A
- collects urine from major calyces
2. funnel shaped duct that becomes continuous with the ureter
10
Q
what is the ureter
A
smooth muscle tube
drains urine from renal pelvis and descends to the bladder
11
Q
how long is the ureter
A
25-35cm long
12
Q
three regions of constriction of the ureter
A
- junction of renal pelvis and ureter (ureteropelvic junction)
- as ureter passes over pelvic brim
- as the ureter enters the bladder
13
Q
clinical importance of ureter constriction regions
A
potential for kidney stones to be lodged
14
Q
what facilitates flow of urine into the bladder
A
the smooth muscle that the calyces, renal pelvis and ureteres all contain
15
Q
each lobe of the kidney has?
A
pyramid and cortex surrounding the pyramid
16
Q
what is a nephron
A
functional unit of the kidney for formation of urine
17
Q
how many nephrons do kidneys have
A
1.2 million per kidney
18
Q
types of nephrons
A
- superficial cortical nephrons (85% of total nephrons) - extend partially into the medulla
- mid-cortical nephron - short and long loops
- juxtamedullary nephron - (12% of total nephrons) - extend deep into medulla
19
Q
which type of nephron is responsible for urine concentration
A
juxtamedullary nephrons
20
Q
regions of the nephron
A
- renal corpuscle
- PCT
- Loop of Henle
- DCT
- Collecting duct
21
Q
function of renal corpuscle
A
site of filtration
22
Q
renal corpuscle is formed by?
A
glomerulus
Bowman’s capsule
mesangial cells
23
Q
what is the function of glomerulus
A
site of capillary filtration
24
Q
what is the glomerulus formed by?
A
glomberular capillaries that extend into Bownman’s capsule
25
what is the glomeruluar filtration membrane
capillary wall
| serves as filtration
26
three layers of glomerular filtration membrane
1. capillary endothelium - fenestrated capillary wall
2. basement membrane - negative charge which plays role in filtration
3. capillary epithelium - foot like projections that form matrix of filtration slits
27
another name for capillary epithelium
podocytes
28
blood supply to the glomerulus
1. afferent arteriole
2. efferent arteriole
3. juxtaglomerular apparatus (JGA)
29
function of afferent arteriole
regulated flow of blood into glomerulus to optimize filtration
30
function of efferent arteriole
glomerulus capillaries drain into efferent arteriole
| -blood then travels to peritubular capillaries
31
importance of blood flowing from efferent arteriole to peritubular capillaries
allows reabsorption and secretion along the tubules of the nephrons
32
what makes up the JGA
juxtaglomerular cells + macula densa
33
where are juxtaglomerular cells located
adjacent to afferent glomerular arteriole
34
what is the macula densa
- cells in distal convoluted tubule located adjacent to afferent and efferent glomerular arterioles
- macula densa cells function as sodium-chloride receptors
35
JGA regulates what?
renal blood flow
glomerular filtration
renin secretion
36
what are mesangial cells
matrix of smooth muscle and phagocytic cells
located bw glomerular capillaries and Bowman's capsule
functional role in regulating filtration
37
what is the Bowman's capsule
collects filtrate from glomerular capillaries
38
what is the space inside the Bowman's capsule
Bowman's space
39
what is the PCT
proximal convoluted tubule
- continuation from Bowman's capsule
- 15mm long, single layer of cells along wall with microvilli (brush border) along the lumen
40
function of microvilli in PCT
provide large surface area for reabsorption
41
function of PCT
major site of sodium reabsorption (and other substances) as filtrate travels through tubules
42
Loop of Henle composed of?
composed of descending and ascending loops
43
functional characteristic of Loop of Henle depends on what?
function varies by location
44
2 locations of Loop of Henle
1. nephrons located near medulla (juxtamedullary nephron)
| 2. nephrons in cortical area (superficial cortical and mid cortical nephrons)
45
function of Loop of Henle - nephrons located near medulla
Loop of Henle extends deep into the medulla - concetrates urine
46
function of Loop of Henle - in cortical area
Loop of Henle - short and only partially extend into medulla - doesn't play role in concentrating urine
47
location of DCT and what it stands for
distal convoluted tubule
| -begins at macula densa and end at connection to collecting duct
48
function of DCT
1. early DCT - continues to dilute filtrate as reabsorbs sodium
2. late DCT - begins to concentrate the fluid as it enters collecting duct
49
DCT's from many nephrons drain into?
single collecting duct
50
collecting duct descends where?
to the renal papilla and drain into minor calyces
51
function of collecting duct
final concentration of urine
52
how are kidneys unique?
they have two successive capillary networks
53
pathway of blood supply to the kidney
descending aorta --> R/L renal arteries --> multiple branches eventually form afferent glomerular arterioles -->supply glomerular capillary beds (site of filtration)
54
what happens to blood after glomerular capillary beds
blood exits glomerular capillary beds via efferent arterioles and contribute to two capillary beds in the nephron
55
what are peritubular capillary beds
surround the PCT and DCT and some of the short Loop of Henle
56
function of peritubular capillary beds
secretion and reabsorption of filtrate throughout the tubules of the nephrons
57
what two capillary beds does the blood from efferent arteriole contribute to?
1. pertubular capillaries
| 2. vasta recta
58
what is the vasa recta
run parallel to the long loops of Henle
59
function of vasta recta
plays critical role in concentrating urine by regulating concentration gradients along loop of Henle
60
pressure in glomerular capillary beds and what does this facilitate?
high pressure system to encourage filtration
61
pressure of glomerular capillary bed at start vs end
-45mmHg at the start
| pressure drops by 1-3 mmHg at the end of glomerular capillary beds
62
pressure in peritubular capillaries and what does this facilitate
lower pressure to encourage exchange (absorption/secretion)
| 8mmHg
63
blood leaves the kidney via what vein
renal vein
64
what is the pressure of blood as it leaves kidney via renal vein
4mmHg
65
what is RBF
renal blood flow - volume of blood that flows thru the glomerular capillaries of both kidneys/min
66
normal RBF
1.2L/min (20-25% of resting CO)
67
what is RPF
renal plasma flow - volume of plasma that flows thru the glomerular capillaries of both kidneys/min
68
avg RPF
600-700ml/min
69
how to calculate RPF
RPF = RBF x (1-HCT)
if HCT = 45% then 1.2*(1.0 - 0.45) = 660 ml/min
70
what is the GFR
glomerular filtration rate - volume of plasma that is filtered into Bowman's capsule per unit of time
71
approx how much of the plasma flowing thru glomerular capillaries of both kidneys will filter into Bowman's capsule?
20-25%
72
avg GFR
120ml/min
73
calculate GFR
GFR = 20% x RPF
0.2* 600ml/min = 120ml/min
74
what happens to the remaining 80% of RPF that does not flow thru glomerular capillaries
flow to peritubular capillaires/vasa recta
75
how much of the GFR is reabsorbed back into the blood stream
approx 98-99% is reabsorbed into the peritubular capillaries as it travels thru the tubules
76
what is the FF
filtration fraction - ratio of GFR to RPF
77
avg FF?
0. 2
| 0. 2 = 120/660
78
what volume (and %) of GFR is excreted / min
1-2ml (1-2%)
79
calculate urine production/min
urine output = GFR * 1.5%
ex. 120 ml/min * 0.015 = 1-2 ml/min
80
how much plasma do the kidneys filter in a day
approx 180L/day (based on GFR of slightly >120ml/min)
81
what is average urine output per day
1-2L/day
82
how much would kidney reabsorb each day?
approx 178-179 L/day
83
how long does it take to filter entire plasma volume
45 mins
84
renal blood flow and pressure must be maintained at _______ levels for optimal GFR/filtration function
constant
85
GFR is directly related to what
RBF
| -if decr in RBF = decr in GFR
86
what could give you a decreased RBF?
decreased MAP or increased total vascular resistance
87
how does the body maintainRBF/GFR despite systemic changes in MAP/vascular resistance?
the body has feedback mechanisms to maintain them
88
how is RBF/GFR regulated
1. autoregulation
2. neuroregulation
3. hormonal feedback mechanisms
- the net result of all three determines actual RBF/GFR
89
what is autoregulation of GFR
local feedback mechanism in the kidney will keep GFR constant despite fluctuations in systemic pressures/resistance
90
the systemic arteriole BP can vary from what pressures without significant change in GFR?
80-180mmHg
91
if systemic arteriole BP exceeds upper or lower threshold pressures what happens to RBF/GFR?
1. if arterial pressures are great than 180-210 then RBF and GFR increase
2. if arterial pressures are less than 70-80mmHg then RBF and GFR decrease
92
how does autoregulation maintain constant GFR - if systemic pressures increase?
glomerular afferent arterioles will constrict
constriction of arterioles will limit RBF
this prevents an increase in GFR as systemic pressures increase
93
how does autoregulation maintain constant GFR - if systemic pressure decrease?
glomerular afferent arterioles will dilate
dilation of arterioles will increase RBF
this prevents a decrease in GFR as systemic pressure drop
94
2 mechanisms of autoregulation of the kidneys
1. myogenic mechanism (stretch feedback)
| 2. tubuloglomerular feedback
95
what is the myogenic mechanism of autoregulation of GFR
- smooth muscle of afferent arteriole wall is sensitive to stretch
- if systemic pressures cause afferent arteriole to stretch then smooth muscle constricts
- the afferent arteriole constriction limits RBF
96
what is tubuloglomerular feedback of autoregulation of GFR
- macula densa located in DCT near afferent/efferent arterioles is sensitive to flow rate and sodium levels in the renal tubules (DCT)
- changes in sodium and flow rates will also signal constriction/dilation of afferent arterioles
ex. increased NaCl thru the macula densa represents an increased GFR
ex. an increase in NaCl in the macula signals the afferent arterioles to constrict and decrease the GFR by slowing the RBF
97
what is neuroregulation of GFR
sympathetic nervous system provides feedback mechanism to regulate/influence GFR
98
if systemic BP decreases how does neuroregulation respond?
- baroreceptors in aortic arch and carotid sinus sense decrease BP and stimulate sympathetic nervous system
- sympathetic nervous system stimulates the renal/glomerular arterioles to constrict
- arteriole constriction limits RBF which either maintains or decreases GFR
99
why would a corresponding decrease in GFR be beneficial as a result of neuroregulation?
1. the goal of the sympathetic nervous system is to increase systemic BP
2. if they can decrease GFR then less sodium/water will be filtered and excreted
3. this will promote an increase in systemic blood volume and BP
100
exercise and GFR
sympathetic mechanisms causes the decrease in RBF and GFR that occur during exercise
101
hemorrhage and GFR
hemorrhaging stimulates large sympathetic response for survival
-sympathetic activity decreases RBF/GFR to promote increased blood volume/pressures
102
2 hormones that regulate GFR
1. RAAS - decrease GFR/increase fluid resorption/decrease fluid excretion
2. natriuretic peptides - increase GFR/decrease fluid reabsorption/increase fluid excretion
103
RAAS pathway to regulate GFR
Liver - produces pre-angiotensin
Kidney - release renin
blood stream - renin converts pre-angiotensin to angiotensin I
lungs - produce ACE into pulm capillaries
--ACE converts angiotensin I to angiotensin II - stimulates multiple events to promote increased BP/volume and sodium retention
104
where is renin synthesized and released
synthesized in and released from juxtaglomerular cells of juxtaglomerular apparatus
-release renin into afferent glomerular arteriole
105
RAAS - goal of RAAS ?
to increase BP/blood volume
106
stimulus of RAAS
decreased BP/blood volume
- sympathetic activity stimulate renin release
- decrease glomerular pressure stimulates renin release
- decrease Na/Cl flow thru macula densa stimulates renin release
107
action of RAAS
stimulate sympathetic activity and renin release
108
sympathetic action due to RAAS
1. increase vasoconstriction = incr BP
| 2. stimulate renin release
109
renin activity d/t RAAS
angiotensin II release
110
increased angiotensin II and increased aldosterone =?
increased fluid/NaCl reabsorption in nephron
111
actions of angiotensin II
1. vasoconstriction of blood vessels
2. stimulate thirst centers in brainstem
3. enhances sympathetic function by promoting release of norepinephrine
4. stimulate adrenal cortex to release aldosterone (increase NaCl reabsorption in distal nephron)
5. sitmulate posterior pituitary gland to release ADH (increases water/fluid reabsorption in distal nephron)
6. decreases peritubular capillary hydrostatic pressure, which promotes increased fluid reabsorption in distal nephron
7. stimulates contractions of mesangial cell (results in decr GFR)
8. long term = vascular hypertrophy
112
inhibition of renin
increased GFR or NaCl flow
increased systemic/glomerular BP
negative feedback of increased angiotensin II and ADH
113
stimulus of renin
sympathetic nervous system/activity
decreased systemic/glomerular BP (renal hypotension)
decreased NaCl flow in distal tubule (macula densa receptors)
114
what are natriuretic peptides
group of peptides that counteract the RAAS
115
name the peptides included in Natriuretic peptides
1. ANP (atrial natriuretic peptide)
2. BNP (brain natriuretic peptide)
3. CNP (C-type natriuretic peptide)
4. urodilatin (renal natriuretic pepetide)
116
where is ANP produced and secreted
produced and secreted from atrial walls of heart
117
where is BNP produced and secreted
right ventricle (and brain)
118
where is CNP produced/secreted
from vascular endothelium in heart
119
where is urodilatin secreted
DCT/collecting ducts
120
functions of ANP/BNP
inhibit secretion of renin and aldosterone
promote sodium/water excretion
---increase GFR = vasodilation of glomerular afferent arterioles
inhibit sodium/water reabsorption in tubules
121
function of CNP
promotes vasodilation of blood vessels
122
function of urodilatin
promotes sodium/water excretion in DCT/collecting ducts
