Topic 1 Part A Flashcards
(68 cards)
1
Q
Excretion= [formula]
A
Filtration–Reabsorption + Secretion
2
Q
Filtration occurs in the
A
glomerulus
3
Q
Reabsorption and secretion occur in the
A
Proximal tubule
loop of Henle;
distal tubule
collecting tubule
4
Q
Filtration rate= [formula]
A
GFR x Plasma concentration
- -Glucose concentration = 1 g/L
- -GFR = 180 L/day
- -Filtration rate = (1 g/L) x ( 180 L/day) = 180 g/day
5
Q
Kidneys has independent control over
A
exertion rate by changing appropriate reabsorption rate
6
Q
Tubular Reabsorption-Mechanisms (4)
A
- From tubular lumen into tubular cells
- From tubular lumen into tubular interstitial space
- From interior of cell into tubular interstitial space
- From interstitial space into peritubular capillary
7
Q
From tubular lumen into tubular cells is a
A
transcellular path
8
Q
From tubular lumen into tubular interstitial space is a
A
paracellular path
9
Q
From interstitial space into peritubular capillary is driven by
A
capillary filtration forces [bulk flow]–net movement into the capillaries
10
Q
Tubular Reabsorption–Mechanisms (A): involves both
A
active and passive mechanisms
11
Q
Tubular Reabsorption–Mechanisms (A): primary active transport (4)
A
Na-K ATPase
Hydrogen ATPase
H-K ATPase
Ca ATPase
12
Q
Tubular Reabsorption–Mechanisms (A): Secondary active transport/co-transport (2)
A
Sodium-glucose
Sodium-amino acids
13
Q
Tubular Reabsorption–Mechanisms (B): Secondary active/co-transport (1)
A
Sodium-hydrogen
14
Q
Tubular Reabsorption–Mechanisms (B): Pinocytosis (requires energy) =
A
Proteins–once in cell broken down to component amino acids and amino acids reabsorbed
15
Q
Tubular Reabsorption–Mechanisms (B): Passive (2)
A
Osmotic movement of water
Bulk flow into peritubular capillaries
16
Q
Reabsorption rate % for glucose
A
100%
17
Q
Reabsorption rate % for Bicarb
A
> 99.99%
18
Q
Reabsorption rate % for Sodium
A
99.4%
19
Q
Reabsorption rate % for Chloride
A
99.1%
20
Q
Reabsorption rate % for Potassium
A
87.8%
21
Q
Reabsorption rate % for Urea
A
50%
22
Q
Reabsorption rate % for Creatinine
A
0%
23
Q
Sodium Reabsorption (A): Sodium pumped out of tubular cells into the interstitial spaces and then…
A
Potassium pumped into tubular cells
- -Na-K ATPase on basolateral sides of tubular epithelial cells
- -Creates membrane potential-70 mV
24
Q
Sodium Reabsorption (A): Sodium follows concentration gradient from tubular lumen into the
A
tubular cells (diffusion down concentration & electrical gradients) --Brush board of proximal tubule luminal membrane creates huge surface area for diffusion (20x increase)
25
```
Sodium Reabsorption (B): Sodium reabsorption also
enhanced by
```
carrier proteins through luminal membrane
| --Co-transport & counter-transport proteins
26
Sodium Reabsorption (B): Sodium quickly moves (along with water) from interstitial fluid into
peritubular capillary
27
```
Glucose Reabsorption (A):
Co-transport mechanism tied to sodium gradient from _______ to _______
--So efficient that usually removes all filtered ______
```
Co-transport mechanism tied to sodium gradient from tubular lumen to interior of tubular cells
--So efficient that usually removes all filtered
glucose
28
Glucose Reabsorption (A):
Two luminal transporters– _____ and _____
-- ____% glucose reabsorbed via _____ in early part of proximal tubule
-- ____% reabsorbed in later part of proximal tubule via ____
Two luminal transporters–SGLT2 and SGLT1
- -90% glucose reabsorbed via SGLT2 in early part of proximal tubule
- -10% reabsorbed in later part of proximal tubule via SGLT1
29
Glucose Reabsorption (B):
Two basolateral glucose transporters– _____ and _____
--______ transport down glucose concentration gradient
-- ______ early stages of proximal tubule with ____ in the later stages
Two basolateral glucose transporters–GLUT2 and GLUT1
- -Passive facilitated transport down glucose concentration gradient
- -GLUT2 early stages of proximal tubule with GLUT1 in the later stages
30
```
Glucose Reabsorption (B):
Bulk flow moves glucose from ________ into the _____
```
Bulk flow moves glucose from interstitial spaces into the peritubular capillaries
31
Amino Acid Reabsorption:
Co-transport mechanism tied to sodium gradient from ________ to __________
--So efficient that usually removes all filtered ______
Co-transport mechanism tied to sodium gradient from tubular lumen to interior of tubular cells
--So efficient that usually removes all filtered amino
32
Amino Acid Reabsorption:
| ______ system pumps the amino acids into the cells
Luminal co-transporter
33
Amino Acid Reabsorption:
| Amino acids diffuse out of the cells into the _______
interstitial spaces
34
Amino Acid Reabsorption:
| Bulk flow moves the amino acids from ____ into the ____
interstitial spaces into the peritubular capillaries
35
Hydrogen Secretion
- -Counter-transport mechanism tied to sodium gradient from ______ to _______
- -Sodium-hydrogen exchanger is located in brush boarder of the ________
- -Counter-transport mechanism tied to sodium gradient from tubular lumen to interior of tubular cells
- -Sodium-hydrogen exchanger is located in brush boarder of the luminal membrane
36
Maximum Level of Active Reabsorption:
Transport maximum: Max amount of solute that
can be reabsorbed (transport max transport)
--Occurs when
tubular load (amount of solute delivered to tubule) exceeds transport capacity of carrier proteins
37
```
Maximum Level of Active Reabsorption:
Filtered load versus transport maximum
--Glucose Tmax = _______
--Glucose filtered load = GFR x [Glu] = 125 mls/min x 1
mg/ml = _____
```
--Glucose Tmax = 375 mg/min
--Glucose filtered load = GFR x [Glu] = 125 mls/min x 1
mg/ml = 125 mg/min
38
```
Maximum Level of Active Reabsorption:
Threshold conc (approx. ____ mg/dL) is concentration where glucose first appears in urine
```
Threshold conc (approx. 200 mg/dL) is concentration where glucose first appears in urine
--Less than T max because each individual nephron is
different–chart represents action of both kidneys so
Tmax reached when ALL nephrons have reached their
max
39
Transport max: glucose=
375 mg/min
40
Transport max: amino acids=
1.5 mM/min
41
Transport max: plasma protein=
30 mg/min
42
Transport max: creatinine (actively secreted)=
16 mg/min
43
Transport max: para-aminohippuric acid (activley secreted)=
80 mg/min
44
Two excretion rates: #1
| Before secretion Tmax is reached, so the amount excreted is the sum amount of...
filtered and amount secreted (steepest slope of excretion curve)
45
Two excretion rates: #2
| After secretion Tmax is reached, the rate of excretion...
parallels filtration rate (slope of excretion curve matches slope of filtration curve)
46
Gradient-Time Transport:
Solute that is reabsorbed _______ and some ______
reabsorbed solute may not show maximum rate of
transport
Solute that is reabsorbed passively and some actively
reabsorbed solute may not show maximum rate of
transport
47
Gradient-Time Transport:
| Rate of transport depends on: (4)
Electrochemical gradient for solute
Membrane permeability for solute
Time fluid containing solute remains in tubule
Transport rate inversely related tubular flow rate
48
Sodium Reabsorption: Proximal Tubule
| Sodium does not show a transport maximum even though it is
actively reabsorbed
49
Sodium Reabsorption: Proximal Tubule
Capacity of _____ usually much greater than rate of net ______
-Significant amount of transported sodium leaks back into the ______
--Permeability of _______ between cells
--Forces controlling bulk flow of water & solute into ____
Capacity of Na-K ATPase usually much greater than rate of net sodium reabsorption
- Significant amount of transported sodium leaks back into the tubular lumen
- -Permeability of tight junctions between cells
- -Forces controlling bulk flow of water & solute into peritubular capillaries
50
Sodium Reabsorption: Proximal Tubule
As plasma concentration of sodium ______, sodium
concentration in proximal tubule ______ and sodium
reabsorption _______
As plasma concentration of sodium increases, sodium
concentration in proximal tubule increases and sodium
reabsorption increases
51
Sodium Reabsorption: Proximal Tubule
| A decrease in tubular flow rate will also increase
sodium reabsorption
52
Sodium Reabsorption: Distal Tubule
| Sodium reabsorption shows classic
tubular max transport
53
Sodium Reabsorption: Distal Tubule
Capacity of Na-K ATPase does not exceed rate of _____
-Minimal back leak of ____ into tubular _____
-Tighter (less permeable tight junctions) ____ transport of much smaller amount of ____
Capacity of Na-K ATPase does not exceed rate of net sodium reabsorption
- Minimal back leak of sodium into tubular lumen
- Tighter (less permeable tight junctions) coupled transport of much smaller amount of sodium
54
Sodium Reabsorption: Distal Tubule
| Aldosterone increases the
Tmax level
55
Passive Reabsorption: Water
| Driven by _______ created by movement of solute (mainly sodium) from ______ to the _______
Driven by osmotic differences created by movement of solute (mainly sodium) from tubular lumen to the tubular interstitial spaces
56
Passive Reabsorption: Water
Affected by cellular ______ (cell membranes and tight junctions)
-Increased permeability means increased _____ and decreased _______
Affected by cellular permeability (cell membranes and tight junctions)
-Increased permeability means increased reabsorption and decreased water excretion
57
Passive Reabsorption: Water
| Permeability of proximal tubule
high
58
Passive Reabsorption: Water
| Permeability of Loop of Henle (ascending loop):
low
59
Passive Reabsorption: Water
| Permeability of Distal tubule / Collecting tubules / Collecting ducts
variable
60
Passive Reabsorption: Water: Proximal tubule
- ____ movement so overall solute gradient across cell is ____
- Solvent drag: water carries significant amount of (5) because of _____ permeability
- Rapid movement so overall solute gradient across cell is minimal
- Solvent drag: water carries significant amount of sodium, chloride, potassium, calcium, magnesium because of high permeability
61
Passive Reabsorption: Water: Loop of Henle (ascending loop):____ movement of water even though there is a large ________
Little movement of water even though there is a large osmotic gradient
62
Passive Reabsorption: Water: Distal tubule / Collecting tubules / Collecting ducts:
Cellular permeability depends on presence of ______
-Permeability _____ related to ______
-Changing water permeability only affects amount of water reabsorbed not the amount of ____ due to ____ solute permeability
Cellular permeability depends on presence of antidiuretic hormone (ADH)
- Permeability directly related to [ADH]
- Changing water permeability only affects amount of water reabsorbed not the amount of solute due to low solute permeability
63
Passive Reabsorption: Chloride & Urea
| Sodium diffusion into cells creates
electrical gradient that pulls negative chloride ions into the cell
64
Passive Reabsorption: Chloride & Urea
| Movement of water into cells concentrates
chloride creating concentration gradient into cell
65
Passive Reabsorption: Chloride & Urea
| Chloride also linked to co-transport mechanism with
sodium across the luminal membrane
66
Passive Reabsorption: Chloride & Urea
| Movement of water into cells concentrates urea creating
concentration gradient into cell
| -but urea not nearly as permeable as water
67
Passive Reabsorption: Chloride & Urea
| Inner medullary collecting duct contains specific
passive urea transports which facilitates reabsorption
68
Passive Reabsorption: Chloride & Urea
| Only ___% of filtered urea is reabsorbed
50%
