FLUID BALANCE

Question 1

how is fluid balance maintained?

Answer 1

through monitoring of blood volume, blood flow, and blood osmolarity

Question 2

Fluid intake increases blood volume..thus

Answer 2

blood pressure increases

If too much water is gained, blood osmolarity decreases

Question 3

Fluid output decreases what?

Answer 3

blood volume and blood pressure

if too much water is lost than blood osmolarity increases

Question 4

Decreased water intake/dehydration

explain the effects of this on fluid balance

Answer 4

Increased blood osmolarity stimulates release of ADH from anterior pituitary
ADH also stimulates thirst center as well as increased water resorption, decreasesed water loss, and vasoconstriction.

Thus blood pressure increases, blood volume increases, blood osmolarity decreases.

Question 5

Decreased blood pressure cause…

Answer 5

decrease in bp causes sympathetic stimulation. JG release renin
renin activates angiotensin and it becomes angiotensin 1,
renin also activates ACE and converts angiotensin 1 to angiotensin 2.
angiotensin 2 effects:
vasoconstriction(increase bp), decreases GFR(less fluid loss), activates thirst center(fluid intake), release of ADH from pituitary, adrenal cortex release of aldosterone

Question 6

How does ADH work?

Answer 6

stimulants: angiotensin II(low bp), low blood volume, and increased osmolarity (dehydration)
hypothalamus responds to these stimulants by activating the posterior pituitary to release ADH.
ADH causes activation of thirst center(increased fluid intake), increased water resorption, (decreases water lost) and vasoconstriction(increases bp)

therefore bp increases, blood volume increases, blood osmolarity decreases

Question 7

How does Aldosterone work?

Answer 7

Stimulants: angiotensin II, decreased Na+ blood plasma levels, increasedK+ levels,

Andrenal cortex responds
releases aldosterone
binds to cause
-increased sodium and water reabsorption to blood
-decreases sodium and water loss in urin
-increases K+ secretion into tubular fluid
Na+ maintained
K+ decreases
blood pressure and volume maintained by dereasing urine output

Question 8

How does ANP work?

Answer 8

Stimulates: increased stretch of atrial barorecptors (high bp)
Atria respond by releasing ANP
ANP:
-vasodilation
-increased GFR
-increased loss of Na+
-decreased release of renin (less aldosterone and ADH)

Thus:

• peripheral resistance decreases
• blood volume decreases
• blood pressure decreases

Question 9

Angiotensin II, ADH, aldosterone all work to

Answer 9

decrease urine output

maintain/increase blood volume and pressure

Question 10

ANP works to

Answer 10

increase urine output and decrease blood volume and pressure