Ch 25 Body Fluid Compartments

Question 1

What is the Donnan effect?

Answer 1

tldr: negative-charged plasma proteins influence cation-anion distribution.
The concentration of cations is slightly greater in the plasma than in the interstitial fluid because negatively charged plasma proteins bind Na+ and K+. Conversely, anions have a higher concentration in intracellular fluid because the negative charge of plasma proteins repels them.

Question 2

Which ions are most prolific in intracelluar fluid?

Answer 2

K+, Phosphate, Mg++, Sulphate

Question 3

Which are the major ions of the extracellular fluid?

Answer 3

Na+ Cl- and HCO3-

Question 4

What does the term isosmotic refer to?

Answer 4

iosmotic means the solution has an osmolarity the same as the cell, regardless of if the solute can penetrate the cell membrane

Question 5

Which conditions cause hyponatremia?

Answer 5

diarrhea, vomiting, diuretic overuse, adrenal insufficiency, excess ADH, bronchogenic tumors

Question 6

Which conditions cause hypernatremia?

Answer 6

Excessive sweating, primary aldosteronism, diabetes insipidus, cushing’s disease (non equine)

Question 7

When sodium rapidly falls to below ____ mmol/L, brain swelling may occur

Answer 7

115-120

Question 8

Why does chronic-developing hyponatremia need to be slowly corrected?

Answer 8

Too-rapid correction outpaces the brain’s ability to recapture solutes lost from cells. Neurons may then experience demyelination

Question 9

How can you safely correct chronic hyponatremia?

Answer 9

Only correct it by <10-12 mmol/L in 24 hours, or by < 18 mmol/L in 48 hours.

Question 10

Which three conditions are especially prone to cause intracellular swelling?

Answer 10

1. Hyponatremia
2. Depressed tissue metabolism
3. Lack of adequate cell nutrition

Question 11

When does extracellular edema develop?

Answer 11

1. abnormal fluid leakage from plasma to interstitium
2. Failure of lymphatics to return fluid from interstitium back into blood

Question 12

Below what plasma protein level does generalized edema develop?

Answer 12

Below 2.5 g/100ml

Question 13

Why does pitting edema “pit”, and why do not all types of edema do this?

Answer 13

Pitting edema occurs when fluid can flow in the interstitium, so digital pressure can displace fluid within the gel/proteoglycan filament network. Nonpitting edema is when the fluid is accumulated within cells, or when it has clotted within the extracellular/interstitial space with fibrinogen

Question 14

Which three mechanisms create the safety factors against edema formation?

Answer 14

1. Low tissue compliance in the negative pressure range
2. Increased lymph flow
3. Protein washdown from the interstitial spaces