Regulation of Water Balance Flashcards
Which part of the body regulate water balance via the kidneys?
Hypothalamus
When the body experiences a fluid deficit or an increase in plasma osmolarity, what two things does the hypothalamus stimulate?
Thirst: Encouraging the individual to drink water.
Release of Antidiuretic Hormone (ADH): The posterior pituitary gland releases ADH under hypothalamic control.
How does ADH act on the kidneys?
Acts on the collecting ducts of the nephrons, promoting the reabsorption of water back into the bloodstream
What 2 hormones help regulate ECF volume?
ADH
Adrenal cortex hormones
cortisol & aldosterone
How does aldosterone help regulate ECF water balance?
Enhances sodium retention and potassium excretion
How does long-term steroid use lead to ECF volume excess?
Steroids can mimic the action of aldosterone, causing sodium retention
Primary organ for regulating fluid and electrolyte balance
Kidneys
Approximately, how much urine do the kidneys make per day
1.5 L
Daily water intake and output are between __ and __ mL
2000 and 3000 mL a day
What hormone in the cardiac system plays a role in fluid regulation?
Atrial natriuretic factor
What does atrial natriuretic factor to help regulate fluid balance?
It reduces sodium reabsorption in the kidneys, causing more sodium, and consequently water, to be lost in urine
By decreasing blood volume, ANF helps lower blood pressure
Which system accounts for most of the water intake?
GI
What does water intake include?
Fluids
Water from food metabolism
Water present in solid foods
Why do diarrhea and vomiting lead to significant fluid and electrolyte loss?
They expel lots of fluid and electrolytes
They prevent GI reabsorption of secreted fluids
What is insensible water loss?
Invisible vaporization from the lungs and skin that cannot be measured
Normal amount of insensible loss per day?
900 mL
Insensible water loss should not be confused with?
Water excreted from sweat glands
Four categories of causes of fluid imbalances?
ECF Volume Deficit
- increased loss
- decreased intake
ECF Volume Excess
- increased retention
- increated intake
ECF Volume Deficit - Increased Loss
vomiting
diarrhea
fistula drainage
gi tract suction
third-spacing
overuse of diuretics
hemorrhage
ECF Volume Deficit - Decreased Intake
nausea
anorexia
inability to drink
inability to obtain water
ECF Volume Excess - Increased Retention
heart failure
cushing’s syndrome
liver disease
long-term use of corticosteroids
renal failure
ECF Volume Excess - Increased Intake
rare when renal function is adequate
excessive IV administration of fluids
