Fluid and Electrolytes

Question 1

What does oncotic pressure do?

Answer 1

pulls fluid into the venous end of the capillary; reabsorption

Question 2

What does hydrostatic pressure do?

Answer 2

pushes fluid from the arterial end of a capillary out; filtration

Question 3

How does oncotic pressure affect net movement of fluid?

Answer 3

oncotic pressure increases pressure in the capillary by pulling fluid in

Question 4

How does hydrostatic pressure affect the net movement of fluid?

Answer 4

hydrostatic pressure pushes fluid out of the vessel

Question 5

What are the potential mechanisms for edema?

Answer 5

1) increased capillary hydrostatic pressure
2) decreased capillary oncotic pressure
3) increased capillary permeability
4) lymph obstruction

Question 6

How would the Starling forces and net movement of fluid change in the following:
A child suffering from protein starvation

Answer 6

oncotic capillary pressure would decrease because the protein required to exert force (albumin) is in low supply; water would start to shift out of the vessel and edema would increase

Question 7

How would the Starling forces and net movement of fluid change in the following:
A man with right-sided heart failure

Answer 7

hydrostatic capillary pressure would increase; this would cause edema

Question 8

How would the Starling forces and net movement of fluid change in the following:
A woman with a blood clot in the femoral vein

Answer 8

hydrostatic pressure would increase as blood cannot be pushed through as effectively; water would move out of the vessel

Question 9

What are the functions of BNP and ANP?

Answer 9

these natriuretic peptides act like diuretics to increase fluid output and Na+ excretion

Question 10

What is the function of aldosterone?

Answer 10

aldosterone signals the kidneys to retain fluid as well as Na+ which increases blood pressure

Question 11

What does antidiuretic hormone (ADH) do?

Answer 11

ADH acts to retain fluid in the body which increases blood pressure; this increases plasma volume but decreases plasma osmolarity

Question 12

What do baroreceptors in the body do?

Answer 12

baroreceptors detect a lack of stretch in major arteries and signal a need to increase blood pressure by stimulating ADH release

Question 13

What do osmoreceptors do?

Answer 13

osmoreceptors track osmotic pressure in the body and signal thirst to trigger ADH secretions when Na+ is in excess in the body

Question 14

List two causes of hypernatremia and why each leads to this imbalance

Answer 14

1) excess Na+ - leads to not enough Na+ being taken into cells, leaving it in high amounts in the bloodstream
2) water deficiency - decreased fluid input leads to a high concentration of sodium in the blood

Question 15

List two causes of hyponatremia and why each leads to this imbalance

Answer 15

1) water intoxication - too much water in the bloodstream decreases the concentration of Na+
2) not enough Na+ - could be from lack of ingestion or other factors, this lowers concentration in bloodstream as there is less Na+ supply

Question 16

List two causes of hyperkalemia and why each leads to this imbalance

Answer 16

1) decreased aldosterone secretion - leads to less Ka+ being excreted
2) K+ shifting out of cells - this leads to excess amounts in the bloodstream (ex. injury/trauma, cell lysis)

Question 17

List two causes of hypokalemia and why each leads to this imbalance

Answer 17

1) increased aldosterone secretion - causes an increase in K+ excretion which lowers levels in blood
2) K+ shifting into cells - leads to lower level in blood (ex. alkalosis, insulin administration)

Question 18

What physiological mechanisms are activated when trying to correct hypernatremia?

Answer 18

1) increase in ADH secretion so not as much fluid/Na+ is maintained (increase in aldosterone to exrete Na+)
2) decreased output of urine
3) thirst

Question 19

How does having kidney dysfunction affect a patient’s ability to correct hypernatremia?

Answer 19

ADH may not be secreted as much so less fluid is retained

Question 20

How does being unconscious affect a patient’s ability to correct hypernatremia?

Answer 20

the patient cannot drink fluid/be thirsty, therefore they will need fluid administered via IV therapy

Question 21

Is it a good idea to give insulin to a patient who is hypokalemic? Why or why not?

Answer 21

NO! Insulin causes K+ to move into cells which will worsen the hypokalemia

Question 22

What can happen to the potassium levels in a person with diabetes if they are without insulin for a long period of time?

Answer 22

they can become hyperkalemic as insulin isn’t present to help pull K+ into cells which causes a surplus in the bloodstream