Lecture: Renal Flashcards
(96 cards)
1
Q
What ions does the kidney regulate?
A
Na, K. Ca, Cl, and phosphate
2
Q
What four things do the kidneys regulate in relation to blood?
A
- Blood pH and osmolarity
- Blood glucose via gluconeogenesis
- Regulation of blood volume by conserving or eliminating water
- Regulation of blood pressure
3
Q
How do the kidneys regulate blood pressure?
A
By secreting the enzyme renin or adjusting renal resistance
4
Q
Which two hormones are released by the kidney
A
Erythropoietin and calcitriol
5
Q
How much blood plasma is filtered by the kidneys every minute?
A
125 mL
6
Q
How much blood plasma is filtered by the kidneys each day?
A
180 L
7
Q
What are the four major physiological functions of the kidneys?
A
- Filtration
- Reabsorption
- Secretion
- Excretion
8
Q
What do kidneys perform their actions on?
A
Blood plasma not blood cells
9
Q
What percent of a kidney must be damaged in order for it to be evident
A
More than 75%
10
Q
Components of the renal corpuscle
A
Glomerulus: a knot of capillaries where filtration occurs
Glomerular capsule: epithelial cup that collects filtrate
11
Q
Site of plasma filtration
A
Renal corpuscle
12
Q
Site of reabsorption from filtrate and secretion into filtrate
A
Renal tubules
13
Q
In which capillaries does blood filtration occur?
A
glomerular capillaries
14
Q
Which capillaries carry away substances reabsorbed from filtrate?
A
Peritubular capillaries and the vasa recta
15
Q
What is the role of sympathetic vasomotor nerves in the blood supply of the kidney?
A
Sympathetic vasomotor nerves regulate blood flow and renal resistance by altering the diameter of aterioles
16
Q
Which cells are hormone receptors found on in the nephron loop?
A
- DCT cells
- Principle cells of the collecting duct
17
Q
Which cells are microvilli found on in the nephron loop?
A
- PCT cells
- Intercalated cells of the collecting duct
18
Q
What produces the filtration pressure in the glomerulus?
A
Blood pressure
19
Q
Fenestrated endothelium filter…
A
blood cells
20
Q
Basement membrane (basal lamina) filter…
A
Large proteins
21
Q
Podocytes filter…
A
medium-sized proteins
22
Q
Total pressure that promotes filtration
A
Net filtration pressure
23
Q
Equation for net filtration pressure
A
Glomerular blood hydrostatic pressure - capsular hydrostatic pressure - blood colloid osmotic pressure
24
Q
Amount of filtrate formed in all renal corpuscles of both kidneys per minute
A
Glomerular filration rate
25
Average glomerular filtration rate in adults
125 mL/min
26
What happens if the glomerular filtration rate is too high?
The useful substances are lost due to the speed of the fluid passage through the nephron
27
What happens if the glomerular filtration rate is too low?
Sufficient waste products may not be removed from the body
28
A glomerular blood hydrostatic pressure lower than ___ stops filtration
45 mmHg
29
Thickened part of ascending limb of loop of henle
Macula densa
30
Modified muscle cells that line the afferent arteriole
Juxtagomerular cells
31
What composes the juxtaglomerular apparatus
Macula densa + juxtaglomerular cells
32
Contractile cells associated with capillaries
Mesangial cells
33
Mechanisms that maintain a constant GFR despite changes in arterial blood pressure
- Myogenic mechanism
- Tubuloglomerular feedback
34
Which form of autoregulation of the GFR causes smooth muscle contraction reduces diameter of afferent arteriole to return the GFR back to its previous level
Myogenic mechanism
35
Which form of autoregulation of the GFR causes an increase in the blood pressure stretch of the afferent ateriole
Myogenic mechanism
36
Which form of autoregulation of the GFR raises the GFR by elevating systemic BP in order to rapidly push fluid through the renal tubule
Tubuloglomerular feedback
37
Which form of autoregulation of the GFR causes afferent aterioles to constrict therefore reducing the GFR
Tubulogolmerular feedback
38
In tubuloglomerular feedback, what happens when macula densa in the ascending limb detect an increase in Na and Cl?
It inhibits the release of NO (a vasodilator) from the juxtaglomerular appartus
39
In which mechanism are blood vessels of the kidney supplied by sympathetic fibers that cause vasoconstriction of afferent arterioles
Neural regulation of the glomerular filtration rate
40
How does vasoconstriction of afferent arterioles occur in neural regulation of the GFR?
Norepinephrine releases from sympathetic postganglionic neurons and binds to the alpha 1 adrenergic receptors
41
What are the two main functions of the SNS in the neural regulation mechanism of the glomerular filtration rate?
1. Override renal autoregulation
2. Stimulate renin release from juxtaglomerular cells
42
At rest, when sympathetic activity is minimal in the kidney, what is the state of the renal blood vessels?
They are maximally dilated
43
When there is moderate sympathetic stimulation of the kidney, what is the state of renal blood vessels?
The afferent and efferent arterioles are constricted equally
44
Does the GFR increase or decrease in the presence of moderate sympathetic stimulation?
The GFR decreases slightly
45
When there is extreme sympathetic stimulation of the kidney, in cases such as exercise or hemorrhage, what is the state of the renal blood vessels?
Afferent arterioles are predominately vasoconstricted
46
Does the GFR increase or decrease in the presence of extreme sympathetic stimulation?
The GFR decreases substantially
47
In the presence of extreme sympathetic stimulation, how are urine output and blood flow affected?
Urine output is lowered in order to maintain the blood volume, allowing a greater blood flow to other tissues in the body
48
Which two hormones contribute to the regulation of the glomerular filtration rate?
1. Atrial Natriuretic Peptide
2. Angiotensin II
49
Which hormone increases the glomerular filtration rate?
Atrial natriuretic peptide
50
What causes a release of atrial natriuretic peptide from the heart?
A high blood volume causes atrial stretching signaling a release of ANP
51
What is the function of atrial natriuretic peptide?
ANP relaxes glomerular mesangial cells, increasing glomerular capillary surface area and increasing the GFR
52
Which hormone reduces the glomerular filtration rate?
Angiotension II
53
What causes the release of angiotensin II?
Angiotensin II is activated by ACE in the lungs which is followed by the release of renin from the juxtaglomerular cells
54
What is the function of angiotensin II?
Angiotensin II acts as a vasoconstrictor to narrow afferent and efferent arterioles and reduce the GFR
55
Where does most reabsorption occur?
The proximal convoluted tubule (PCT)
56
How do small proteins move from the tubular fluid back into blood?
Pinocytosis
57
What are the two main purposes of tubular secretion?
1. Control blood pH by secreting H
2. Eliminating waste substances
58
Difference between tubular reabsorption and tubular secretion
Reabsorption - transfers materials from tubular fluid back into blood
Secretion - transfers materials from blood into tubular fluid
59
What type of reabsorption is it when the reabsorbed material is moved between cells by diffusion in parts of the tubule?
Paracellular reabsorption
60
What type of reabsorption is it when the reabsorbed material moves through both the apical and basal membranes of the tubule by active transport?
Transcellular reabsorption
61
Which membrane does Na/K ATPase pump sodium from the tubule cell cytosol through?
Basolateral membrane
62
How is water reabsorbed?
Through osmosis
63
Obligatory water reabsorption is when water is...
obliged to follow solutes being reabsorbed
64
Facultative water reabsorption is under the control of...
antidiuretic hormone (ADH)
65
Na symporters
Glucose
Amino acids
Lactic acid
Water-soluble vitamins
66
The reabsorption of nutrient is...
Isosmotic - meaning that the water follows the solutes
67
What must the concentration of Na be for reabsorption in the proximal convoluted tubule?
Low intracellular concentration
68
What do Na antiporters do in relation to secretion in the proximal convoluted tubule?
Secrete acid (H+)
69
What does drug secretion rely on in the proximal convoluted tubule?
- Organic anion and cation transporters in the basolateral membrane
- MATE (multi-drug and toxin extruder) proteins
- H+ gradient
70
Which substances have a renal threshold?
All substances that are reabsorbed by nephron cells
71
Glucose in urine
Glycosuria or glucosuria
72
What is the glucose renal threshold?
200 mg/dL
73
Where does osmosis occur in the loop of Henle?
Descending limb
74
Where does reabsorption of NaCl occur in the loop of Henle?
Thing ascending limg
75
What is the descending limb permeable to?
The descending limb is permeable to water, but not to NaCl
76
What is the ascending limb permeable to?
The ascending limb is permeable to NaCl but not to water
77
The thick ascending limb of the loop of Henle has Na/K/2Cl symporters that reabsorb these ions...
1. K moves back into filtrate through K leak channels
2. Na is pumped out of the basolateral side
3. Cl diffuses across the cell
78
How do cations move across the vasa recta?
They are drawn to the negative charge in the capillary
79
What is the early distal convoluted tubule permeable to?
It reabsorbs ions, but is more permeable to water
80
All water reabsorption until the late distal convoluted tubules is...
obligatory
81
The two types of cells in the late distal convoluted tubule and collecting duct are...
1. Principal cells
2. Intercalated cells
82
What do principal cells reabsorb?
1. Na
2. If ADH is present, H2O
83
What do principal cells secrete?
K+
84
What do intercalated cells reabsorb?
1. K+
2. HCO3-
85
What do intercalated cells secrete?
H+
86
What is the goal of water reabsorption of H2O in the late DCT and CD?
Remove excess fluid from blood by producing dilute urine
87
Process which produces a progressively-increasing osmotic gradient in interstitial fluid of renal medulla
Countercurrent multiplication
88
Process which enables oxygen delivery to cells of renal medulla without loss of the osmotic gradient in interstitial fluid of renal medulla
Countercurrent exchange
89
Two main factors that contribute to building and maintaining the required osmotic gradient
1. Permeability differences
2. Countercurrent flow
90
Where are permeability differences present?
Sections of the loop of Henle and the collecting duct
91
Where is countercurrent flow present?
Within tubular fluid in the descending and ascending loop of Henle
92
Symporters in the thick ascending limb cells of the loop of Henle cause a buildup of...
Na and Cl in the interstitial fluid of the renal medulla
93
The descending limb is very permeable to water, but impermeable to solutes except...
urea
94
What establishes an osmotic gradient in the renal medulla?
Countercurrent flow through the descending and ascending limbs
95
Osmolarity difference between the outer interstitial fluid of the descending limb and the inner tubular fluid
Osmolarity of the interstitial fluid outside of the descending limb is higher than the osmolarity of the tubular fluid
96
Why does water move out of the descending limb into the interstitial fluid via osmosis?
Osmolarity differences
