Lecture 17: Renal Physiology Flashcards
1
Q
if RBF is too low, the afferent arteriole:
A
relaxes
2
Q
if RBF is too high, the afferent arteriole:
A
constricts
3
Q
this vessel is primarily responsible for autoregulation of renal blood flow
A
afferent arteriole
4
Q
this vessel is primarily responsible for fine-tuning GFR
A
efferent arteriole
5
Q
what effect does increasing afferent arteriole resistance have on glomerular pressure?
A
decreased glomerular pressure
6
Q
what effect does decreasing glomerular presure have on GFR?
A
decreased GFR
7
Q
what effect does increasing afferent arteriole resistance have on renal blood flow?
A
decreased renal blood flow
8
Q
what effect does decreased renal blood flow have on GFR?
A
decreased GFR
9
Q
what effect does increasing efferent arteriole resistance have on glomerular pressure?
A
increasing glomerular pressure
10
Q
what effect does increasing glomerular pressure have on GFR?
A
increased GFR
11
Q
what effect does increasing efferent arteriole resistance have on renal blood flow?
A
decreased renal blood flow
12
Q
what effect does increased glomerular pressure have on GFR?
A
increased GFR
13
Q
what would cause a decreased renal blood flow?
A
- increased afferent arteriole resistance
- increased efferent arteriole resistance
14
Q
what effect would dilation of the afferent arteriole have on GFR?
A
dilation of afferent > increased glomerular pressure > increased GFR
15
Q
what effect would dilation of the efferent arteriole have on GFR?
A
dilation of efferent arteriole > decreased glomerular pressure > decreased GFR
16
Q
what might cause impediment of arterial dilation?
A
- being sick/critically ill
- chronic hypertension
- uncontrolled diabetes
17
Q
GFR autoregulation is dependent on
A
renal blood flow autoregulation
18
Q
GFR is better regulated at higher or lower blood pressures?
A
higher; at pressures of 50 mmHg or lower, GFR has a steeper decline than when BP is closer to 150 mmHg or higher (a more shallow, flatter slope)
19
Q
GFR autoregulation at high pressures prevents the kidneys from:
A
spilling massive amounts of fluid into the urine
20
Q
the normal UOP rate
A
1 ml/min
21
Q
as MAP increases, UOP:
A
increases
22
Q
as MAP decreases, UOP:
A
decreases
23
Q
in terms of autoregulation:
with an initial rise in BP, then we’ll have an increase in RBF, then GFR is increased, UOP ____ and, therefore, blood pressure will _____
A
- increases
- decrease
24
Q
in terms of autoregulation:
with an initial decrease in BP, then we’ll have a decrease in RBF, then GFR is decreased, UOP ____ and, therefore, blood pressure will _____
A
- decreases
- increase
25
filtration only:
some substances are completely reabsorbed
26
filtration with partial reabsorption:
some substances are partially reabsorbed
ex) Na+
| excessive Na+ in our diet gets partially reabsorbed
27
filtration with complete reabsorption:
some substances are filtered and secreted
ex) glucose (in a NON-DM patient)
normally, **ALL** of the glucose gets **COMPLETELY** reabsorbed in the **PCT**
28
filtration with secretion
some substances are filtered and secreted
ex) **paramino hippuric acid (PAH)**
29
in filtration with secretion, how much substance gets filtered and how much gets secreted?
1. 1/5 gets filtered
2. 4/5 gets secreted
30
what is PAH and why is it used?
paramino hippuric acid
it is used as a diagnostic compound to measure **renal blood flow** by observing how much of the compound is cleared by the kidneys
the **more** **PAH** that is **cleared** by the kidneys, the **higher** the **RBF** is
the **less** **PAH** that is **cleared** by the kidneys, the **lower** the **RBF** is
31
what is the normal reabsorption rate?
124 ml/min
32
urinary excretion = ?
filtration - reabsorption + secretion
33
NFP = ?
Pcap - Pisf - Picap + Piisf
34
what is the innermost layer of the glomerular capillaries?
endothelium
| these are MORE permeable than generic capillaries
35
the porous openings in the glomerular capillary endothelium
fenestrations
36
the layer superficial to glomerular endothelium capillaries
basement membrane
37
what is the purpose of the epithelium in glomerular capillaries?
houses **podocytes** which provide structural support; the capillary beds resist a lot of increased pressure and the podocytes provides structural support to prevent glomerular swelling
38
the podocytes have foot processes that have openings called:
split pores
39
the glomerular capillaries have a (positive/negative) charge within membrane
negative
40
what is the benefit to having negative charges scattered within the glomerular capillary?
to repel **negatively charged proteins**
41
describe the role of renal podocytes
1. to provide structural support to the glomerular capillaries
2. to prevent glomerular swelling (with structural support) d/t high BP
3. to regulate surface area of glomerular capillaries
42
what is dextran?
a synthetic sugar that is modifiable in compound size
43
polycationic dextran is (more/less) filterable
more filterable
44
polyanionic dextran is (more/less) filterable
less
45
the larger a compound is, the _____ filterable it is
less
46
what is inulin?
a synthetic compound used to accurate way to estimate GFR (similar to creatinine clearance)
47
a filterability of 1.0 =
high filterability
| i.e. H2O
48
a filterability of .005 =
a low filterability
| i.e. albumin
49
roles of the kidney include (9)
1. LT BP regulation
2. LT pH regulation
3. LT [RBC] regulation
4. LT [electrolyte] regulation
5. LT vitamin D regulation
6. LT serum glucose regulation
7. drug clearance
8. LT metabolic waste disposal
9. osmolarity regulation
| all these roles are accomplished with a normal **GFR**
50
*chronic* HTN is a ____ issue
kidney
51
how does the kidney regulate pH levels?
1. the kidneys **produce** HCO3-
2. the kidneys control how much HCO3- gets **reabsorbed**
3. the kidney can get rid of excess protons (H+)
52
what is the *short-term* pH regulator of the body?
the lungs - can blow off excess **CO2** (but not H+ directly)
53
how does the kidney regulate [RBC] levels?
* O2 sensors deep in **medullary portions** of kidney
* low O2 levels > stimulates bone marrow > to produce erythryopoietin (epo) > increase more RBCs
* RBCs will travel to wherever O2 is needed and transport O2 there
54
how does the kidney regulate vitamin D levels?
* the kidney **activates** vitamin D
* activated vitamin D helps the kidney **reabsorb Ca2+**
55
the more glucose that is filtered, the ____ that is reabsorbed
more
56
if serum glucose is past transport max of the kidney, what happens to the glucose?
in extreme hyperglycmia, glucose gets lost/"skimmed off" via excretion in the urine
57
drug clearance occurs mostly in the:
liver
*some* clearance occurs via the kidney
58
how does the kidney regulate osmolarity?
* the kidney is able to differentiate water from NaCl, so it can selectively reabsorb water
* the kidney can also get rid of excess NaCl
* this process is regulated by **ADH** and **osmoreceptors in the BRAIN**
59
delineate the circulation flow from renal artery to renal vein
1. renal artery
2. segmental arteries
3. interlobar arteries
4. arcuate arteries
5. interlobular arteries
6. aferrent arteriole
7. glomerular capillaries
8. efferent arteriole
9. peritubular capillaries
10. arcuate veins
11. interlobar veins
12. segmental veins
13. renal vein
60
which structures make up a nephron?
* afferent arterioles
* glomerular capillaries
* efferent arterioles
* peritubular capillaries
PLUS tubular network:
* PCT
* DCT
* Loop of Henle
* cortical collecting tubule
* collecting duct
61
each KIDNEY has how many nephrons at birth?
1 million
62
at birth how many nephrons do we have?
2 million
63
at what age do we start to lose nephrons (d/t "wear & tear")
40 yrs old
64
superficial nephrons AKA
cortical nephrons
65
deep nephrons AKA
inner medullary nephrons
66
what percentage of our nephrons are cortical?
90-95%
67
what percentage of our nephrons are inner medullary?
5-10%
68
there are fewer peritubular capillaries in the (outer medulla/inner medulla)?
inner medulla
69
the outer medulla's peritubular capillaries reabsorb compunds from:
the cortical nephrons
70
between ascending & descending blood vessels in the inner medulla, there are more of the:
ascending blood vessels
71
why are there more ascending blood vessels in the inner medulla?
there are more split points in the ascending blood vessels
72
why is it important to have "split points" in the ascending blood vessels in the inner medulla?
* more split points will cause a **decreased blood flow velocity** in the ascending blood vessels
* this is important to maintain **solute concentration in the interstitium** of the inner medulla
* decreased blood flow velocity in the ascending blood vessels **prevents "wash out" of solutes**
73
concentrated solutes in the renal interstitium is beneficial for the process of
reabsorption
*accomplished with the help of decreased blood flow velocity in ascending blood vessels*
74
deep/inner medullary peritubular capillaries AKA
vasa recta capillaries
75
which type of nephron is more sensitive to low perfusion in terms of oxygen delivery?
* deep medullary nephrons d/t there only being 5-10% of this type of nephron vs cortical nephrons
* there is a **limited supply** of **peritubular capillaries** located in the deep medulla
| PT capillaries play a large role in **reabsorption** AND **O2 delivery**
76
kidneys lie underneath the
diaphragm
77
renal artery and vein lie deep to the
mesenteric arteries
78
which arteries supply blood to the intestines?
mesenteric arteries
79
how many adrenal glands do we have?
2
| 1 adrenal gland lies on top of each kidney
80
how many ureters do we have?
2
81
suprarenal glands AKA:
adrenal gland
| supra = above; above renal
82
this kidney comes into contact with the liver
RIGHT kidney
| the liver is on the right side
83
this kidney comes into contact with the stomach, spleen, and the pancreas
LEFT kidney
84
which kidney comes into contact with the colon?
both
85
relate renal surface anatomy to cancer
* kidney cancer is RARE
* surface area contact with other organs is important in terms of cancer spreading to the kidney **(i.e. pancreatic cancer will spread to the middle of the LEFT kidney)**
86
why is renal cancer rare?
* the kidneys **do not** **produce** **new nephrons**
* since there is no cell proliferation, the risk of renal cancer is rare
| *heart CA is also rare*
87
which quadranst of the abdomen do the kidneys lie?
RUQ - R kidney
LUQ - L kidney
88
kidney stones exhibit this type of pain
**referred** pain in the **lower back**
89
the urethra is shorter in:
females
90
the pudendal nerve originates from these spinal nerves
S2, S3, & S4
| S 2-3-4 keeps things off the floor
91
pudendal nerve functions (3)
* bladder emptying
* fecal waste emptying
* boners
92
prostate gland removal increases risk for:
* erectile dysfunction
* incontinence
93
corpuscle AKA:
bowman's capsule
94
which part of the Loop of Henle is thick? thin?
TAL - thick **ascending** limb
DTL/ATL - descending thin limb **AND** ascending thin limb
95
the macula densa lies in:
TAL (thick ascending limb)
96
what do the macula densa cells do?
* "speedometer" of the blood flow/filtration rate
* if low flow is sensed, communicates with **juxtaglomerular cells**
97
what do the juxtaglomerular cells do?
* releases **renin** that release AT-II to *preferentially* relax/constrict the **efferent arteriole**
| renin > angiotensinogen > AT I > ACE > AT II > efferent arteriole
98
if low flow is sensed by MD cells, what happens?
* JG cells release **RENIN**
* renin releases **AT II** to **preferentially **constrict EA
* constricted EA > decreased RBF > occludes outflow from GCs
* GCs hydrostatic pressure increases
* increased GC pressure > increased filtration rate
99
if high flow is sensed by MD cells, what happens?
* JG cells restrict **RENIN** release
* EA dilates > increases RBF
* GCs hydrostatic pressure decreases
* decreased GC pressure > decreased filtration rate
100
clearance rate =
| equation
Cx = V̇ x Ux/Px
ml/min
101
GFR =
| equation
GFR = Uinulin x V̇/Pinulin
102
RBF =
| amount
1100 ml/min
| ~ 22% of CO
103
RPF =
| equation for renal plasma flow
RPF = (1-Hct) x RBF
RPF = 0.60 x 1100 ml/min
ml/min
| 1-0.40 (Hct) = plasma volume (0.60)
104
excretion rate
| equation
= Ux x V̇
mg/min, mmol/min, mEq/min
105
ERPF (effective renal plasma flow) =
| equation
EPRF = CPAH = UPAH x V̇/PPAH
ml/min
106
reabsorption rate =
| equation
= filtered load - excretion rate
= (GFR x Px) - (U x V̇)
mg/min, mmol/min, or mEq/min
107
