11.22 A Flashcards
The osmolality of the extracellular body fluid fraction can increase in what two ways?
- addition of impermable solutes
- loss of water from the extracellular fraction
The osmolality of the extracellular body fluid fraction can decrease in what two ways?
- loss of impermeable solutes
- addition of water to the extracellular fraction
How can fluid be added or lost from the extracellular body fluid fraction in an isotonic manner?
- loss of blood (via hemorrhage)
- infusion of saline
An increase in ECF volume is called what?
an expansion
A decrease in ECF volume is called what?
a contraction
An increase in ECF volume will have what effect on the cardiovascular system?
- increase plasma volume
- increase venous return
- increase preload of ventricles
- increase stroke volume
- increase cardiac output
- increase MAP
A decrease in ECF volume will have what effect on the cardiovascular system?
- decrease plasma volume
- decrease venous return
- decrease preload of ventricles
- decrease stroke volume
- decrease cardiac output
- decrease MAP
What are the six types of volume and electrolyte disturbances?
- hypotonic expansion or contraction
- isotonic expansion or contraction
- hypertonic expansion or contraction
Give an example of a hypotonic expansion.
excessive water intake
Give an example of a hypotonic contraction.
salt loss (kidney)
Give an example of an isotonic expansion.
IV infusion of saline
Give an example of an isotonic contraction.
hemorrhage
Give an example of a hypertonic expansion.
IV infusion of hypertonic saline
Give an example of a hypertonic contraction.
dehydration
What is a hypotonic contraction?
a volume and electrolyte disturbance that decreases ECF volume and and decreases the ECF osmolality
IV saline will have what effects on TBW volumes?
ECF will increase and ICF will remain unchanged
What would happen if you drank too much water?
ECF volume increases and the osmolality decreases so water flows into the ICF fraction and that increases as well
Bleeding will result in what sort of body fluid disturbance?
it would be an iostonic contraction
What happens to someone when they become dehydrated?
loss of ECF volume, loss of ICF volume and blood volume, which leads to diminished MAP
Give the equation for calculating water deficit.
H2O deficit = present TBW x {(current[Na] / desired [Na]) - 1}
A massive intake of sodium what increase the osmolality of what body fluid fraction?
the extracellular fraction
A massive intake of sodium what have what effects on ICF and ECF volume?
it would increase ECF volume at the expense of ICF volume
A kidney defect that impaired the reabsorption of sodium would have what effects on ICF and ECF volume?
ECF osmolality would decrease and water would move into the ICF fraction, increasing the ICF volume
What is the most common electrolyte disorder?
hypovolemic hyponatremia
What is hypovolemic hyponatremia?
the most common electrolyte disorder, it is characterized by a loss of sodium from the ECF
Give the equation for calculating one’s sodium deficit.
Na deficit = TBW x (desired[Na] - present [Na])
What is the role of arginine vasopressin?
- aka anti-diuretic hormone (ADH)
- released in response to increased body fluid osmolality
- acts to increase water reabsorption by the kidneys
Thirst increases when what happens to body fluid?
the osmolality exceeds 290 mOsm
What is the role of aldosterone?
a hormone that stimulates the kidney to increase sodium reabsorption in exchange for potassium
What are the two major natriuretic peptides?
BNP and ANP
What is BNP?
a major natriuretic peptide released from cardiac ventricles in response to champer distension
- works to increase water and sodium output by the kidney
What is ANP?
- a major natriuretic peptide released from cardiac atria in response to champer distension
- works to increase water and sodium output by the kidney
