Fluid Compartments Flashcards

1
Q

Suppose you have two chambers of water separated by a selectively permeable membrane. The chambers are labeled A and B respectively and initially the equal-sized chambers are both half-full with pure water. The membrane is permeable to water and sodium, but impermeable to potassium and chloride. What will happen with respect to net movement of water if chamber A suddenly has 100 mM potassium chloride? a) Water will shift from chamber A to chamber B. b) Water will shift from chamber B to chamber A. c) There will be no net movement of water. d) Potassium will diffuse from chamber A to chamber B.

A

b -

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2
Q

Suppose a person is given a 1 liter intravenous infusion of isotonic NaCl solution. How much of this fluid will remain in the extracellular space? a) None b) About 1/3 c) About 2/3 d) All

A

d - all

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3
Q

The sodium-potassium pump hydrolyzes one molecule of ATP each time it moves 3 sodium ions out of the cell and 2 potassium ions into the cell. What type of transport does this carrier protein perform? a) Simple diffusion b) Facilitated diffusion c) Primary active transport d) Secondary active transport

A

C - primary active transport

Primary active transport implies the direct consumption of metabolic energy (e.g., ATP hydrolysis). Secondary active transport implies a two component system – a primary active transporter that creates an ion gradient, and a co-transporter that exploits the gradient but does not directly utilize metabolic energy.

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4
Q

Which body compartment has 2/3 of the body fluid at any given time: intra or extracellular?

A

intracellular

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5
Q

What are the two divisions for extracellular fluid?

A

interstitial (75%) and plasma (25%)

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6
Q

Which of the following solutes are high in extracellular fluid? Na cl glucose K Mg phosphate

A

Na, Cl, and glucose

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7
Q

Which of the following are high in intracellular fluid? Na Cl Glucose K Mg Phosphate

A

K, Mg, Phosphate

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8
Q

Does the intracellular or extracellular fluid have a higher protein concentration?

A

intracellular fluid

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9
Q

What is the Donnan effect?

A

small differences in ionic composition of plasma and interstitial fluid attributed to the Donnan effect (also known as Gibbs-Donnan equilibrium). This effect arises because plasma proteins have a net negative charge but cannot leave the vascular compartment obligating a greater number of positively charged ions to remain in plasma and more negatively charged ions to stay in the interstitium.

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10
Q

What are the two forces driving transport across a semi permeable membrane?

A

Diffusion pressure and membrane potential

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11
Q

What is another word for diffusion pressure?

A

chemical gradient

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12
Q

The net electrochemical gradient is a sum of what two forces driving transport?

A

Diffusion pressure/chemical gradient and membrane potential

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13
Q

Define secondary active transport

A

When the potential energy stored in a chemical concentration gradient is used to drive transport of another ion

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14
Q

How is facilitated diffusion different to passive transport?

A

facilitated diffusion is a special subclass of passive transport in which a simple transporter is involved in moving a solute down it’s concentration gradient (i.e. binds the thing and moves it, not just an open channel)

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15
Q

How is urea transported (of the types of transportation learned in lecture?)

A

via facilitated diffusion

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16
Q

What are the three broad categories of channels?

A

voltage gated ligand gated leak channels

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17
Q

How are leak channels defined?

A

leak channels mediate passive movement of ions or water WITHOUT requiring stimulation by membrane potential or ligands (i.e. they are tonically open)

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18
Q

What are the two broad types of ATPase pumps?

A

P type V type

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19
Q

What are V type ATPase pumps?

A

vacuolar pumps for protons

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20
Q

What is the difference between osmolality and osmolarity?

A

osmolality is osmoles (active solute molecule) per Kg of water while osmolarity is by LITER of water

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21
Q

Why is osmolality preferred over osmolarity when discussing physiology?

A

volume changes with temperature of the body, but mass does not

22
Q

What is the osmole gap?

A

the different between measured and estimated Posm values that can point to accumulations of unmeasured osmoles such as ethanol

23
Q

A solution with higher osmolality than the interior of the cell is hypotonic or hypertonic?

A

hypertonic

24
Q

A cell in a hypertonic solution will: shrink or swell?

A

Shrink - driving force pushes water out of the cell to balance out the solutes there

25
Q

A cell in a hypotonic solution will: shrink or swell?

A

swell - water will go into the cell to balance out the osmoles inside the cell

26
Q

When does herniation of the brain occur in a setting of abnormal tonicity?

A

when the brain fluid is hypotonic compared to the cells, the cells will swell within the skull and press against the cranium

27
Q

How do you treat a brain herniation due to hypotonic extracellular fluid?

A

you administer IV osmotic active substances such as mannitol, which promotes water movement out of the cells and temporarily reverses brain swelling. Mannitol will not move into the cells and therefore is restricted to ECF

28
Q

What is a cellular short term response to hypotonic solution?

A

Cells exposed to hypotonic solution that begin to swell from passive water uptake will respond by releasing intracellular ions such as K and Cl such that the osmotic gradient is reduced and the direction of water movement is reversed. This is regulatory volume decrease

29
Q

What is regulatory volume decrease?

A

Cells exposed to hypotonic solution that begin to swell from passive water uptake will respond by releasing intracellular ions such as K and Cl such that the osmotic gradient is reduced and the direction of water movement is reversed.

30
Q

In hypertonic solution, what is the short term response of the cell to shrinkage?

A

In hypertonic solution when cells begin to shrink upon passive water loss, transport of Na, K and Cl will be activated to increase intracellular osmolality and promote water uptake. This is a regulatory volume increase.

31
Q

What is regulatory volume increase?

A

In hypertonic solution when cells begin to shrink upon passive water loss, transport of Na, K and Cl will be activated to increase intracellular osmolality and promote water uptake.

32
Q

What are idiogenic osmoles?

A

changes in osmotically active molecules as a long term response to hypo or hypertonic solutions - i.e. taurine, glycine, glutamine, sorbitol and inositol

33
Q

taurine, glycine, glutamine, sorbitol and inositol are all examples of what kind of molecules?

A

idiogenic osmoles, which are regulated as long term adaptations to hyper or hypotonic solution

34
Q

What effect will isoosmotic saline solution have on ECF and ICF?

A

only ECF volume will increase, osmolality will not change

35
Q

What effect will hypoosmotic saline have on ECF and ICF?

A

both ICF and ECF will increase, osmolality will be reduced overall

36
Q

What effect will hyperosmolar saline have on ECF and ICF?

A

expand ECF but reduce ICF due to increased osmolality of ECF

37
Q

Under severe conditions of fever, dry climate or hyperventilation, what happens to ECF and ICF?

A

dehydration via pure water loss - both ICF and ECF will decrease (2/3 from cells and 1/3 from EC) and osmolality of both will increase by equal magnitudes (although initially will occur more in EC, and this will pull water out of IC)

38
Q

Why is it important to know that the majority of pure water loss in “insensible” dehydration is occuring inside the cells?

A

The effect of pure water loss on plasma volume only represents one-twelfth of the total loss. For example, loss of 1 liter of pure water will result in only 83 ml reduction in plasma volume which is unlikely to cause a change in blood pressure. On the contrary, hypotension in the setting of pure dehydration signifies a profound degree of water loss.

39
Q

Define insensible water loss

A

pure water loss via evaporation and exhaled water vapor

40
Q

What effect will iso osmotic fluid loss have on ICF and ECF?

A

osmolality will not be impacted. ECF will decrease, causing a decrease in BP if severe

41
Q

What effect would excessive sweating, diarrhea, osmotic diuresis or GI/renal fluid loss have on ECF and ICF?

A

this is hypoosmotic fluid loss - reduced ECF at first without changes in osmolality. Loss of pure water will increase osmolality of both ICF and ECF, though not as severely as in cases of insensible pure water loss such as dehydration

42
Q

What is the relationship between loss of 1 liter of hypotonic fluid with an osmolality equal to one half of normal plasma and the corresponding change in BP?

A

For loss of 1 liter of hypotonic fluid that has an osmolality equal to one-half of normal plasma, extracellular volume will be reduced by 667 ml (500 ml of isoosmotic fluid, 167 ml of pure water [one third of 500 ml water]). The reduction in plasma volume will be 25% of the 500 ml of isoosmotic fluid plus one twelfth of the 500 ml water (or 41.6 ml) for a net reduction of 167 ml. ** exposure only ***

43
Q

What is the normal production of H+ in protein digestion?

A

1 mEq of H+ per Kg of body weight with normal dietary protein catabolism

44
Q

What is the waste management function of the kidneys?

A

elimination of phosphates and N wastes, elimination of H+

45
Q

What is the most important factor for regulating BP in the long terM?

A

maintaining proper balance of sodium secretion - Na is the main extracellular solute, so it determines the ECF volume

46
Q

To maintain a constant BP, what must be true of Na intake and excretion?

A

they must be equal

47
Q

What are the two main hormones produced by the kidney?

A

renin and erythropoeitin

48
Q

What two substances are enzymatically activated by the kidney?

A

vitamin D and angiotensin II

49
Q

Which hormones are the kidneys the target organs for?

A

aldosterone, ADH, PTH, and AnP

50
Q

What is the equation that can estimate plasma osmolality?

A