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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
Q

This hormone inhibits Na+, Phos. cotransport, leading to increased urinary excretion of phosphate…

A

PTH

26
Q

What is the TF/P ratio for freely filtered solutes in Bowman’s space?

A

1

27
Q

Reabsorption can produce very ________ TF/P ratios

A

small

28
Q

does osmolarity change with TF/P ratio in the proximal tubule?

A

no

29
Q

TF/P = 1… this means…

A

solute reabsorption = H20 reabsorption

30
Q

TF/P < 1… this means…

A

solute reabsorption > H20 reabsorption

31
Q

TF/P > 1… this means…

A

solute reabsorption < H20

OR

net secretion of solute

32
Q

Why is TF/P of inulin used as a marker?

A

it is only filtered, concentration in tube determined solely by movement of water

33
Q

This measure refers to the maximal rate at which a renal transport system can move a particular solute due to transport protein saturation…

A

Tubular Maximum

34
Q

Anything below the Tubular Maximum (Tm) means the entire filtered load is….

A

reabsorbed

35
Q

When filtered load is above the Tm, what happens?

A

the amount above the FL is excreted

36
Q

Where are most Tms found?

A

proximal tubule

37
Q

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

A

Splay

38
Q

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…

A

threshold

39
Q

Threshold is dependent on what factor of the renal system?

A

GFR

40
Q

If GFR increases above 125, what happens to threshold?

A

decreases due to faster rate

41
Q

If GFR decreases below 125, what happens to threshold?

A

increases

42
Q

What substances have TMs in the kidneys?

A

Glucose and sugars, amino acids, metabolic intermediates, phosphate ions, water soluble vitamins, proteins and peptides

43
Q

Excess unreabsorbed solute (i.e. mannitol) will ______ osmotic water flow from lumen to basolateral spaces…

A

inhibit

44
Q

What happens when mannitol inhibits osmotic water flow from lumen to basolateral space?

A

sodium back diffusion into lumen of tubule causing increased sodium and water loss

45
Q

Osmotic diuresis can result in a rapid loss of ______ leading to what condition

A

loss of sodium and water

polyuria

46
Q

Osmotic diuresis occurs when in diabetics?

A

when glucose load exceeds Tm

47
Q

What are the two main routes for tubular secretion?

A

paracellular

transcellular

48
Q

Paracellular and transcellular mechanisms are non-specific and function for ____

A

organic cations and anions

49
Q

What compounds are secreted?

A

metabolites, waste products, foreign chemicals

50
Q

The liver “tags” secreted compounds with…

A

glucuronic acid or sulfate

51
Q

Organic anions are secreted via…

A

tertiary active transport

52
Q

What transporter allows PAH to be taken into the cell

A

Organic Acid Transporter

53
Q

OAT is a transporter that exchanges PAH for…

A

alpha ketoglutarate

54
Q

Most organic anion secretion involves what 2 transporters?

A

OAT1 and OAT3

55
Q

Where are OAT1 and OAT3 transporters located

A

basolateral membranes of proximal tubule cells

56
Q

What transports organic cations?

A

proximal tubule organic cation transporters (OCTs)

57
Q

Where does most anion and cation secretion occur?

A

late proximal tubule

58
Q

Hippurates
Acetazolamide
Chlorothiazide
Furosemide

These are examples of endogenous chemicals and drugs that are considered _______

A

anions

59
Q 
Amiloride
Creatinine
Dopamine
Epi, NE
Atropine

These are examples of endogenous chemicals and drugs that are considered _______

A

Cations

Physiology II (28 decks)

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