Chapter 6: Renal Physiology Flashcards
1
Q
a fluid containing water, ions, and small soluble compounds
A
urine
2
Q
(1), aka (2), is the elimination of urine
A
- urination
- micturition
3
Q
transports urine toward the urinary bladder
A
ureter
4
Q
temporarily stores urine prior to elimination
A
urinary bladder
5
Q
conducts urine to exterior; in males, transports semen as well
A
urethra
6
Q
the kidneys are stabilized by the ff:
A
- peritoneum
- adjacent organs
- supporting connective tissues
7
Q
the kidney is a () organ -> lies behind the peritoneum
A
retroperitoneal
8
Q
the left renal vein lies between the (1) and (2); (3) occurs when the left renal vein is compressed -> causes abdominal pain and hematuria
A
- abdominal aorta
- superior mesenteric artery
- nutcracker syndrome
9
Q
blood in urine
A
hematuria
10
Q
3 main regions of the kidney
A
- cortex - outer region
- medulla - central region
- papilla - innermost tip
11
Q
the medulla is divided into:
A
inner and outer medulla
12
Q
functional unit of the kidney
A
nephron
13
Q
general segments of a nephron
A
- glomerular capillaries and Bowman’s space
- proximal tubule
- Loop of Henle
- distal (convoluted) tubule
- connecting tubule
- collecting duct
14
Q
a nephron consists of (1) + (2)
A
- glomerulus
- renal tubule
15
Q
2 kinds of nephrons
A
- superficial cortical nephron
- juxtamedullary nephron
16
Q
() nephron has a short loop of Henle
A
superficial cortical
17
Q
() nephron has larger glomeruli and GFR; longer loop of Henle -> makes it essential for concentrating urine
A
juxtamedullary
18
Q
() is a form of specialized epithelium and maintains homeostasis in the nephron; part of the distal convoluted tubule
A
macula densa
19
Q
homeostatic functions of the kidney
A
excretory, regulatory, endocrine
20
Q
the kidney stabilizes blood pH by controlling ()
A
the loss of H+ and HCO3-
21
Q
hormones secreted by the kidney
A
renin, erythropoietin, calcitriol
22
Q
% of blood volume occupied by RBC (typically 0.45)
A
hematocrit
23
Q
interstitial fluid is the () of plasma
A
ultrafiltrate
24
Q
solutes such as NaCl and NaHCO3 are confined to () -> this is where ingested sodium is added
A
ECF
25
Substances which are unable to penetrate the membrane between compartments, and therefore they are effective in their contribution to the osmotic pressure gradient.
effective osmole
26
major solutes of ECF and plasma
Na+, Glucose, BUN (blood urea nitrogen)
27
losing more H2O than Na+
hyperosmotic volume contraction
28
losing more Na+ than H2O
hyposmotic volume contraction
29
volume of plasma completely cleared of a substance by the kidneys per unit ime (mL/min)
renal clearance
30
substances with the (highest/lowest) renal clearances may be completely removed on a single pass of blood through the kidneys
highest
31
normally, urine must not contain any:
albumin, glucose
32
substances that have renal clearances above 0 -> filtered and partially absorbed
Na+, urea, phosphate, Cl-
33
clearance of () reflects volume of blood filtered at glomerulus (renal clearance = GFR)
inulin
34
renal clearance of () represents renal plasma flow because it is filtered and secreted
para-aminohippuric acid (PAH)
35
describe substance clearance ratio
renal clearance of substance / inulin clearance
36
renal blood flow is directly proportional to ()
pressure gradient bet. renal artery and renal vein
37
renal blood flow is inversely proportional to ()
resistance of renal vasculature (afferent and efferent arterioles)
38
vasoconstriction of renal afferent arteriole (increases/decreases) GFR
decreases
39
vasoconstriction of renal efferent arteriole (increases/decreases) GFR
increases
40
Both afferent and efferent arterioles are innervated by sympathetic nerve fibers that produce vasoconstriction by activating
alpha1 receptors
41
(afferent/efferent) arterioles express far more alpha1 receptors compared to the other arterioles
afferent
42
due to increased expression of alpha receptors in afferent arterioles, increased sympathetic activity (increases/decreases) both RBF and GFR
decreases
43
potent vasoconstrictor of both afferent and efferent arterioles; however the latter are more sensitive
angiotensin II
44
GFR is increased by (high/low) levels of angiotensin II; conversely, GFR is decreased by (high/low) levels
1. low
2. high
45
() is secreted from the atrium in response to atrial wall distension -> dilation of afferent art., constriction of efferent art. -> net effect: increase GFR
atrial natriuretic peptide (ANP)
46
() are locally produced in the kidney; causes vasodilation of both afferent and efferent art. -> maintained RBF in case of hemorrhage to protect kidney
prostaglandins
47
low levels of dopamine (dilate/constrict) renal arterioles -> dopamine can be used in the treatment of hemorrhage to protect vital organs
dilate
48
renal arterial pressure can vary from () mmHg, yet RBF will be kept constant
80 - 200
49
as renal arterial pressure increases/decreases, renal resistance must ()
increase or decrease proportionately
50
the juxtaglomerular complex/junction is composed of ()
macula densa and juxtaglomerular (JG) cells
51
fenestrated endothelium has ()
pores
52
in the glomerular filtration barrier, (1) are present on the endothelium, basement membrane, and the epithelium – a barrier not for (2), but for (3)
1. negatively charged glycoproteins
2. small molecules such as ions
3. larger molecules such as plasma proteins
53
GFR is the product of (1) and the (2)
1. Kf (filtration coefficient)
2. net ultrafiltration pressure.
54
The net ultrafiltration pressure, the driving force, is the algebraic sum of the three Starling pressures, except the ()
oncotic pressure in Bowman’s space
55
For glomerular capillaries, the
net ultrafiltration pressure always favors (1), so the direction of fluid movement is always (2)
1. filtration
2. out of the capillaries.
56
assumptions used to simplify calculation of effective renal plasma flow
1. [PAH] in RV = 0
2. [PAH] in RA = [PAH] in any peripheral vein
57
GFR is measured by the clearance of a ()
glomerular marker
58
3 characteristics of a glomerular marker
1. freely filtered across glomerular capillaries
2. can't be reabsorbed or secreted by renal tubule
3. can't alter GFR when infused
59
endogenous marker for GFR
creatinine
60
in chronic heart failure, GFR is decreased due to ()
reduced renal perfusion
61
BUN and creatinine is (increased/decreased) in blood in chronic heart failure
increased
62
increased BUN/creatinine ratio
prerenal azotemia
63
in chronic renal failure, GFR is decreased due to ()
renal dysfunction
64
in chronic renal failure, both BUN and creatinine are (increased/decreased) in blood
increased
65
unlike in chronic heart failure, (urea/creatinine) reabsorption is decreased in chronic renal failure
urea
66
The amount of a substance filtered into Bowman’s space per unit time is called the ().
filtered load
67
The fluid in Bowman’s space and in the lumen of the nephron is called ()
tubular fluid or luminal fluid.
68
in reabsorption, water and many solutes are reabsorbed from the glomerular filtrate into the ()
peritubular capillary blood
69
(): the sum of filtration, reabsorption, and secretion
excretion
70
3 transporters found in proximal tubule cells that are involved in glucose reabsorption
1. Na+ - K+ ATPase (primary active transport)
2. Na+-glucose transporters (SGLT) (secondary active transport)
3. glucose transporters GLUT1, GLUT2 (facilitated diffusion)
71
(): reabsorption approaching saturation, but not fully saturated
Splay
72
the plasma concentration at which glucose is first excreted in the urine is called the (1), but this occurs lower at a plasma concentration than does (2)
1. threshold
2. tubular transport maximum, Tm (SGLT is completely saturated)
73
excretion or spilling of glucose in the urine
glucosuria
74
common causes of glucosuria
1. uncontrolled diabetes mellitus
2. pregnancy (gestational diabetes)
3. SGLT abnormalities
75
SGLT abnormalities result in (increased/decreased) Tm, thus glucose is excreted in the urine at ()
1. decreased
2. lower than normal plasma concentrations
76
the transporters for PAH and other organic acids are located in the () of proximal tubule cells
peritubular membranes
77
weak acids and bases are (1) and (2)
1. filtered in the glomerulus
2. secreted in the proximal tubule
78
relative amounts of charged and uncharged species depend on ()
urine pH
79
only the (charged/uncharged) species can diffuse across cells
uncharged
80
() uring treats aspirin overdose
alkalinizing
81
in all cases, water always follows () when membrane is permeable to water
Na+
82
Na+ - phosphate cotransport is inhibited by ()
parathyroid hormone (PTH)
83
Na+ - H+ exchange is stimulated by ()
angiotensin II
84
generation of () urine accompanies release of angiotensin II
acidic
85
() is a diuretic that inhibits carbonic anhydrase -> leads to urine alkalinization
acetazolamide
86
() cells are responsible for making acidic urine
early proximal convoluted tubule
87
major cellular component of cells in the late proximal convoluted tubule is ()
Cl- - formate anion exchanger
88
the [TF/P] compares the concentration of a substance in (1) with its concentration in (2)
1. tubular fluid (TF)
2. systemic plasma (P)
89
bicarbonate level (increases/decreases) along the length of the proximal tubule; (2) concentration remain the same because they are absorbed isosmotically
1. decreases
2. Na+ and Cl-
90
() is the major regulatory mechanism of the proximal tubule, describing the balance between filtration and reabsorption
glomerulotubular (GT) balance
91
GT balance ensures that ()
constant fraction of filtered load is reabsorbed by proximal tubule
92
changes in ECF volume cause changes in () in the peritubular capillary blood -> affects reabsorption in proximal tubule
Starling forces
93
() cause increased Na+ and water excretion owing to the presence of a poorly absorbed substance in the lumen of the proximal tubule
osmotic diuretics
94
example of osmotic diuretic: filtered by not absorbed
mannitol
95
example of osmotic diuretic: filtered load exceeds reabsorption capacity
untreated diabetes mellitus
96
isosmotic requirement in proximal tubule is due to ()
very permeable membrane
97
in the loop of Henle, the () is impermeable to water -> called the diluting segment
thick ascending limb
98
examples of loop diuretics
furosemide, bumetanide, ethacrynic acid
99
() increases Na+ - K+ - 2Cl- cotransporter activity -> helps generate osmolarity gradient that is required for reabsorption of water in loop of Henle
antidiuretic hormone (ADH)
100
other terms for ADH
vasopressin
101
a terminal nephron consists of ()
distal tubule + collecting duct
102
the terminal nephron is impermeable to (1) -> called (2)
1. water
2. cortical diluting segment
103
class of diuretics that inhibits Na+ - Cl- cotransporter, activated basolateral Na+/Ca2+ exchanger and apical Ca2+ channel leading to Ca2+ reabsorption
thiazide
104
() cells are responsible for reabsorption of Na+, Cl-, and Ca2+
early distal tubule
105
in the cells of the early distal tubule, Ca2+ enter via (1), which is reciprocally regulated by (2)
1, calbindin
2. PTH and calcitonin
106
types of cells in the late distal tubule
principal cells, intercalated cells, distal convoluted tubule cells
107
principal and intercalated cells are the only cells found in the ff parts of the collecting duct
1. cortical collecting duct (CCD)
2. outer medullary collecting duct (OMCD)
3. initial inner medullary collecting duct (iIMCD)
108
the types of cells present in the terminal inner medullary collecting duct (tIMCD) are ()
inner medullary collecting duct (IMCD) cells
109
aquaporin (1/2) is not controlled by ADH -> always present to reabsorb water
aquaporin 1 (AQP1)
110
the late distal tubule and collecting duct are permeable to water via (), which is controlled by ADH -> more ADH in blood, more H2O reabsorption
aquaporin 2 (AQP2)
111
reabsorption of Na+ in the late distal tubule and collecting duct is ()-dependent
aldosterone
112
Na+ reabsorption in the early distal tubule (DCT cells) is ()-dependent
load
113
in the late distal tubule and collecting duct, principal cells secrete
K+
114
examples of K+-sparing diuretics
spironolactone, amiloride, triamterene
115
K+-sparing diuretic: blocks aldosterone receptor
spironolactone
116
K+-sparing diuretic: blocks epithelial Na+ channel (ENaC)
amiloride, triamterene
117
() causes natriuresis by inhibiting ENaC and Na+-K+ ATPase; secreted by the heart
atrial natriuretic peptide (ANP)
118
in the late distal tubule and collecting duct, intercalated cells reabsorb (1) and secrete (2)
1. K+
2. H+
119
in the late distal tubule and collecting duct, aldosterone stimulates (1) to increase H+ secretion
H+ ATPase
120
only (alpha/beta) intercalated cells have primary active transporters at the apical membrane
alpha
121
when blood is basic, intercalated cells switch () type
from alpha to beta
122
beta intercalated cells are responsible for ()
HCO3- disposal
123
thirst is triggered by () of plasma
increase osmolarity
124
only the terminal inner medullary collecting cells (tIMCD) have ()
urea transporter 1 (UT1)
125
() is driving force of water reabsorption
osmolarity gradient
126
benefits of countercurrent multiplication
1. allows efficient reabsorption of solutes and water while leaving organic waste in tubular fluid
2. establishes concentration gradient that permits reabsorption of water from tubular fluid (regulated by ADH)
127
capillary that travels along loop of Henle; participates in countercurrent exchange
vasa recta
128
() is a purely passive process that helps maintain the osmotic gradient generated by countercurrent multiplication
countercurrent exchange
129
() of vasa recta allows the osmolarity of blood and interstitium to always be the same
free permeability
130
main effects of ADH is to stimulate:
1. Na+-K+-2Cl- cotransporter (thick ascending limb)
2. AQP2 (principal cells of late distal tubule and collecting duct)
3. UT1 at tIMCD cells
