Exam 4 Part 1 Flashcards
1
Q
What are the 4 general functions of the kidneys?
A
- maintains body composition (volume, osmolarity, pH)
- excretes metabolites (urea, toxins)
- generates glucose (gluconeogensis)
- produces and secretes hormones/enzymes
2
Q
What is the renal pelvis and ureter?
A
funnels urine into kidneys
3
Q
What supplies blood to the kidney?
What removes blood (containing reabsorbed solutes) from the kidney?
A
supply: renal artery
removes: renal vein
4
Q
What part of the kidneys contains the glomerulus?
A
cortex
5
Q
What are medulla pyramids?
A
contains nephrons and vessels
6
Q
What are minor and major calix?
A
where urine drips into renal pelvis
7
Q
Where on the spine level are the kidneys located?
A
T12 - L3
8
Q
The kidneys are _______________ which means they are outside the peritoneal cavity
A
retro-peritoneal
9
Q
Kidneys receive ___% of cardiac output
A
25%
10
Q
What is reabsorption?
A
solute moves from tubule lumen —> interstitial fluid
- tubule to peritubular capillary
11
Q
What is secretion?
A
solute moves from interstitial fluid –> tubule lumen
- peritubular capillary to tubule
12
Q
What is excretion?
A
removal of solute from tubule via urine excretion
13
Q
What is filtration?
A
removing solute from bloodstream
- capillary to bowmans space
14
Q
What is body mass balance?
A
total input = total output
15
Q
What are the intakes and out takes for body mass balance?
A
intake: food/water and metabolic products
outtake: urine, renal vein, lymphatic output
16
Q
What is the filtration rate fraction?
A
GFR/RPF
17
Q
What’s the order tubules in the nephron?
A
- proximal tubule
- thin descending loop of Henle
- thin ascending loop of Henle
- thick ascending loop of Henle
- distal convoluted tubule
- collecting duct
18
Q
How do you calculate water composition?
A
60% x weight
19
Q
How do you calculate ECF?
A
20% x weight
20
Q
How do you calculate ICF?
A
40% x weight
21
Q
How do you calculate interstitial fluid?
A
75% x ECF
22
Q
How do you calculate plasma volume?
A
25% x ECF
23
Q
What’s the pressure that drives fluid from glomerulus capillary to Bowmans space?
A
hydrostatic pressure
24
Q
What’s the pressure that drives fluid from Bowmans space to the glomerulus capillary?
A
osmotic pressure
25
Na+ and Cl- dominate extracellularly or intracellularly?
extracellularly
26
K+ and phosphate dominate extracellularly or intracellularly?
intracellularly
27
What's more permeable, the cell membrane or the capillary membrane?
capillary membrane
28
What's the driving force for solute movement?
osmolarity/osmolality
29
Intake of a isotonic NaCl solution...
type:
ECF volume:
ECF osmolarity:
type: isosmotic volume expansion
ECF volume: increase
ECF osmolarity: no change
30
Mild diarrhea...
type:
ECF volume:
ECF osmolarity:
type: isosmotic volume contraction
ECF volume: decrease
ECF osmolarity: no change
31
High NaCl intake...
type:
ECF volume:
ECF osmolarity:
type: hyperosmotic volume expansion
ECF volume: increase
ECF osmolarity: increase
32
Excessive sweating...
type:
ECF volume:
ECF osmolarity:
type: hyperosmotic volume contraction
ECF volume: decrease
ECF osmolarity: increase
33
Excessive water intake...
type:
ECF volume:
ECF osmolarity:
type: hyposmotic volume expansion
ECF volume: increase
ECF osmolarity: decrease
34
Adrenal insufficiency...
type:
ECF volume:
ECF osmolarity:
type: hyposmotic volume contraction
ECF volume: decrease
ECF osmolarity: decrease
35
What is GFR?
how much blood is filtered by glomerulus
36
How do you calculate filtered load of a solute?
GFR x [solute in plasma]
37
How do you calculate excretion rate of solute?
urinary flow x [solute in urine]
38
During reabsorption, filtered load ___ excretion rate of solute
filtered load > excretion rate
39
During secretion, filtered load ___ excretion rate of solute
filtered load < excretion rate
40
What is clearance?
measurement of renal function to clear a solute (vol/time)
41
Why inulin a good marker for GFR?
freely filtered by the glomerulus, is not secreted or reabsorbed in the tubules
* trapped in tubule lumen
42
How do you calculate the clearance (GFR) of a solute?
urinary flow x [solute in urine] / [solute in plasma]
43
For inulin, filtered load ___ excretion rate
filtered load = excretion rate
44
[creatinine] in plasma is __________ proportional to GFR
inversely proportional
45
What are the 3 filtration barriers that determine the composition of the ultra-filtrate?
1. capillary endothelium
2. glomerulus basement membrane
3. podocyte foot process
46
Out of all 3 of these, which is the most resistant to large molecules?
1. capillary endothelium
2. glomerulus basement membrane
3. podocyte foot process
3. podocyte foot process
(closet layer to bowman's space)
47
Does hydrostatic pressure or osmotic pressure favor filtration?
hydrostatic pressure
48
Is hydrostatic pressure or osmotic pressure the driving force for GFR?
hydrostatic pressure
49
What happens to renal plasma flow if you restrict the afferent arterioles?
decrease
50
What happens to the hydrostatic pressure if you restrict the afferent arterioles?
decrease
51
What happens to the GFR if you restrict the afferent arterioles?
decrease
52
What happens to renal plasma flow if you restrict the efferent arterioles?
decrease
53
What happens to hydrostatic pressure if you restrict the efferent arterioles?
increase
54
What happens to GFR if you restrict the efferent arterioles?
increase then decrease
55
When you restrict the efferent arterioles, why does hydrostatic pressure increase?
resistance downstream (from restricting efferent) causes build up of pressure upstream resulting in LOTS of filtration initially (increase GFR)
protein beings to build up in capillary causing osmotic pressure to eventually rise above hydrostatic pressure = decreased GFR
56
How does changes in arteriole pressure affect glomerulus capillary and why does that affect GFR and hydrostatic pressure? And why?
no affect on any of them (**PRESSURE not resistance)
pressure needs to remain constant as not to filter too much solute
57
What are the 2 mechanisms that auto regulate renal function?
1. myogenic mechanism
2. tubuloglomerular feedback
58
What is the myogenic mechanism of autoregulation?
increased stretch of smooth muscles (die to increased pressure) in arterioles stimulates Ca2+ channels, causing increased intracellular Ca2+ = more tension = more resistance to counteract stretch
59
What is the tubuloglomerular feedback mechanism of autoregulation?
a SINGLE nephron senses increases in lumenal Na+ at the macula densa cells = constriction of arterioles = decreased GFR/RBF
60
How does Angiotensin II affect contraction and aldosterone?
increase contraction -- increase resistance
increase aldosterone -- increase sodium reabsorption
61
How does aldosterone secretion affect...
Na+ reabsorption:
extracellular fluid:
potassium excretion:
increase Na+ reabsorption
increase extracellular fluid
increase potassium excretion
62
What are 2 stimulators of aldosterone?
AT II
hyperkalemia (aldosterone will increase potassium excreation)
63
What does spironolactone block and compete for receptor?
aldosterone
64
What do diuretics do?
increase urine production to reducing fluid build up in body
65
What do prostaglandins (PGE2) do to kidney function?
local vasodilator which allows kidneys to increase flow
66
What is transcellular movement?
through cell
67
What is paracellular movement?
between cells
68
What affect paracellular movement?
voltage (Vte)
69
What affects transcellular movement?
max transport rate
70
What 3 epithelial characteristics affect solute movement?
1. structure of tubule cells
2. asymmetrical distribution of channels/transporters
3. kinetic properties of transporters
71
Does the proximal tubule have complex or simple cells and are they tight or leaky?
complex (very involved in absorption and secretion)
leaky (easier for diffusion)
72
Glucose is transported via an active transporter which means it can become saturated. What is that affect on filtration, excretion, and reabsorption?
only affect reabsorption (only one that uses transporters) become saturated
73
What is Tm in glucose reabsorption and what happens there?
glucose transporter is saturated
resulting in excess glucose in tubule lumen that will be excreted
74
Why is there no glucose excreted at the beginning of the glucose Tm graph?
all the glucose is being filtered and reabsorbed
75
What is the threshold on the glucose Tm graph?
plasma concentration at which solute first appears in urine
76
What segment of tubule reabsorbes the most water?
proximal tubule
77
What solutes are moved across proximal tubule cells for reabsorption?
Na+
Cl-
H2O
only early...
K+
HCO3-
glucose
78
Fluid reabsorption in the proximal tubule is ____osmotic
isosmotic
79
____% of Na+ is absorbed in proximal tubule
67%
80
In proximal tubule, Na+ is transported paracellularly, transcellularly, or both?
both
81
What is the Vte charge in the early proximal tubule and why?
negative (-4 mV)
Na+ paracellularly leaving lumen making it more negative
82
What drives the reabsorption of Na+, Cl-, and H2O in early proximal tubule?
negative Vte
83
What is the Vte charge in the late proximal tubule and why?
positive (+4 mV)
Cl- paracellularly leaving lumen making it more positive
84
Since fluid being reabsorbed in proximal tubule is isosmotic, every solute being absorbed has a _______ molecule reabsorbed with it
H2O
* water passively follows solutes
85
Is hydrostatic pressure or osmotic pressure the driver for reabsorption?
osmotic pressure
86
What is GT balance?
67% of Na+ is always reabsorbed along the proximal tubule, regardless of the change in filtered load
87
What are the 2 factors that affect GT balance?
1. peritubular factors (change in starling forces)
2. luminal factors (tubule flow)
88
If you increase the filtration fraction does the osmotic pressure increase or decrease and how does this aid in the GT balance?
increase
* build up of proteins = increase osmotic pressure = increase reabsorption so that there isn't too much filtration of solute
89
If you increase the filtration does that increase or decrease the hydrostatic pressure and how does this aid in the GT balance?
decrease
* enhances reabsorption so that there isn't too much filtration of solute
90
If you increase filtration fraction there is an increase in tubule flow, what is the affect of on the amount of time of the solute in the tubule and reabsorption?
solute stays in tubule longer and concentration decreases slower = increase reabsorption
91
How much glucose, amino acids, and carboxylates are reabsorbed in proximal tubule?
almost 100%
92
What mechanism is glucose, amino acids, and carboxylates are reabsorbed in proximal tubule?
secondary active transport
* paired with Na+ reabsorption
93
How much potassium and calcium is reabsorbed in proximal tubule?
2/3
94
What ion reabsorption closely follows fluid reabsorption?
K+
95
Does K+ travel mainly paracellularly or transcellularly?
paracellularly
96
Where is most Ca2+ reabsorbed?
thick ascending limb
97
Does Ca+ travel mainly paracellularly or transcellularly?
paracellularly
98
Does Mg+ travel mainly paracellularly or transcellularly?
paracellularly
99
How much Mg+ is reabsorbed in proximal tubule?
15%
100
What ion is excreted the most and why?
phosphate
aids in acid release
101
How much phosphate is reabsorbed in proximal tubule?
80%
102
Does phosphate travel mainly paracellularly or transcellularly?
transcellularly
* active transport
103
Reabsorption of phosphate is ____ limited causing it be excreted in urine.
Tm limited
(uses secondary active transporter)
104
How much HCO3- is reabsorbed in proximal tubule?
80%
105
H+ excretion into lumen is necessary for both reabsorption of ________ and excretion of __________ acids
HCO3-
non-volatile
106
What 2 transporters are used to secrete organic anions?
anion coupled exchanger (apical)
DC2-coupled exchanger (basolateral)
107
What is an example of a organic synthetic anion?
PAH
108
What does the titration curve for PAH look like in terms of secretion?
Tm limited
increases then levels off
(active transporter on basolateral side for secretion)
109
