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Physiology II > Renal Physiology: Tubular Transport > Flashcards

Renal Physiology: Tubular Transport Flashcards

1
Q

What is the formula for transportation rate?

A

Tx = FL - ER

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2
Q

This measure refers to the amount of material either added to (secreted) or removed from (reabsorbed) glomerular filtrate…

A

Transport rate

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3
Q

What units are used in transport rate?

A

mg/min

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4
Q

A positive transport rate indicates…

A

reabsorption of material from filtrate

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5
Q

A negative transport rate indicates

A

secretion of material to filtrate

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6
Q

By what mechanism is glucose transported into the cell across the luminal membrane?

A

via secondary active transport

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7
Q

What energy source enables secondary active transport of glucose across the luminal membrane?

A

Na+ facilitated diffusion (concentration gradient)

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8
Q

Sodium is transported out of the cell and potassium into the cell across the basolateral membrane via…

A

Primary active transport… Na+, K+ ATPase

Cotransport with HCO3-

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9
Q

Glucose crosses the basolateral membrane and is transported out of the cell via…

A

facilitated diffusion

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10
Q

What percent of sodium is reabsorbed in the proximal tubule and by what type of transport?

A

67% reabsorption via active transport

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11
Q

What percent of water is reabsorbed in the proximal tubule and by what type of transport?

A

65% via passive, solute-linked transport

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12
Q

List the areas of sodium reabsorption from greatest to least…

A

proximal tubule&raquo_space; LOH > Distal/collecting tubules

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13
Q

List the areas of water reabsorption from greatest to least…

A

proximal tubule&raquo_space; distal/collecting tubules > LOH

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14
Q

Water reabsorption in the distal tubule and collecting duct is passively transported and NOT solute-linked… what controls its transport then?

A

ADH

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15
Q

Sodium reabsorption in the distal tubule and collecting duct is done via active transport, and is regulated by what hormone?

A

aldosterone

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16
Q

What is the major driving force that allows fluid reabsorption across the basolateral membrane and into the peritubular capillaries?

A

High oncotic pressure in the peritubular capillaries

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17
Q

Sodium is transported from the basolateral membrane into the peritubular capillaries via the Na+, K+ ATPase… how does water cross the basolateral membrane then?

A

passive diffusion following Na+

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18
Q

What is the initial step that drives fluid movement from nephron lumen into the peritubular capillaries?

A

active transport of Na+ across the basolateral membrane

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19
Q

In the proximal tubule, the reabsorption of water and electrolytes is considered hyperosmotic/isosmotic/hyposmotic

A

isosmotic

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20
Q

Sodium transport into the cell from the nephron lumen occurs via facilitated diffusion with a _________

A

Na+, H+ Antiport (sodium/hydrogen exchanger)

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21
Q

In the early proximal tubule, what molecules are reabsorbed?

A

Na+ (NHE)

HCO3-

Organic molecules

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22
Q

What molecules are primarily reabsorbed in the late proximal tubule?

A

NaCl

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23
Q

This hormone stimulates the Na+, H+ exchanger (NHE) to increase Na+ reabsorption and H+ secretion…

A

Angiotensin II

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24
Q

SNS stimulation has what effect on reabsorption?

A

increases Na+ reabsorption

25
This hormone inhibits Na+, Phos. cotransport, leading to increased urinary excretion of phosphate...
PTH
26
What is the TF/P ratio for freely filtered solutes in Bowman's space?
1
27
Reabsorption can produce very ________ TF/P ratios
small
28
does osmolarity change with TF/P ratio in the proximal tubule?
no
29
TF/P = 1... this means...
solute reabsorption = H20 reabsorption
30
TF/P < 1... this means...
solute reabsorption > H20 reabsorption
31
TF/P > 1... this means...
solute reabsorption < H20 OR net secretion of solute
32
Why is TF/P of inulin used as a marker?
it is only filtered, concentration in tube determined solely by movement of water
33
This measure refers to the maximal rate at which a renal transport system can move a particular solute due to transport protein saturation...
Tubular Maximum
34
Anything below the Tubular Maximum (Tm) means the entire filtered load is....
reabsorbed
35
When filtered load is above the Tm, what happens?
the amount above the FL is excreted
36
Where are most Tms found?
proximal tubule
37
On a titration curve showing the tubular maximum, what does the following refer to... a variation on the graph due to the heterogeneity of nephrones, meaning not all nephrons will have the same Tm
Splay
38
On a titration curve showing the tubular maximum, what does the following refer to... The TF/P where a substance first appears in the urine...
threshold
39
Threshold is dependent on what factor of the renal system?
GFR
40
If GFR increases above 125, what happens to threshold?
decreases due to faster rate
41
If GFR decreases below 125, what happens to threshold?
increases
42
What substances have TMs in the kidneys?
Glucose and sugars, amino acids, metabolic intermediates, phosphate ions, water soluble vitamins, proteins and peptides
43
Excess unreabsorbed solute (i.e. mannitol) will ______ osmotic water flow from lumen to basolateral spaces...
inhibit
44
What happens when mannitol inhibits osmotic water flow from lumen to basolateral space?
sodium back diffusion into lumen of tubule causing increased sodium and water loss
45
Osmotic diuresis can result in a rapid loss of ______ leading to what condition
loss of sodium and water polyuria
46
Osmotic diuresis occurs when in diabetics?
when glucose load exceeds Tm
47
What are the two main routes for tubular secretion?
paracellular transcellular
48
Paracellular and transcellular mechanisms are non-specific and function for ____
organic cations and anions
49
What compounds are secreted?
metabolites, waste products, foreign chemicals
50
The liver "tags" secreted compounds with...
glucuronic acid or sulfate
51
Organic anions are secreted via...
tertiary active transport
52
What transporter allows PAH to be taken into the cell
Organic Acid Transporter
53
OAT is a transporter that exchanges PAH for...
alpha ketoglutarate
54
Most organic anion secretion involves what 2 transporters?
OAT1 and OAT3
55
Where are OAT1 and OAT3 transporters located
basolateral membranes of proximal tubule cells
56
What transports organic cations?
proximal tubule organic cation transporters (OCTs)
57
Where does most anion and cation secretion occur?
late proximal tubule
58
Hippurates Acetazolamide Chlorothiazide Furosemide These are examples of endogenous chemicals and drugs that are considered _______
anions
59
``` Amiloride Creatinine Dopamine Epi, NE Atropine ``` These are examples of endogenous chemicals and drugs that are considered _______
Cations

Physiology II (28 decks)

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