Water Balance 2

Question 1

Which hormone stimulates the synthesis of aquaporins?

Answer 1

ADH

Question 2

Which hormone is important for sodium and water reabsorption in the kidney?

Answer 2

Aldosterone

Question 3

Which of the following concerning thirst is true?
A. One stimulus for thirst is a reduced osmolarity in the ECF
B. The thirst center is located in the CNS
C. Blood loss (hemorrhage) would not activate thirst

Answer 3

The thirst center is located in the CNS

Question 4

When is the RAAS activated?

Answer 4

When there is a decrease in the arterial pressure (hypotension).

Question 5

What does Angiotensin II stimulate the release of?

Answer 5

Aldosterone from adrenal cortex

Question 6

What are the effects of Angiotensin II?

Answer 6

Increase thirst, ADH, vasoconstriction, aldosterone.

Decrease hydrostatic pressure.

Question 7

What is the ultimate effect of hypotension?

Answer 7

Increase water retention and arterial blood pressure

Question 8

What is dehydration?

Answer 8

Occurs when water loss is greater than water gain

Question 9

What are 3 effects of dehydration?

Answer 9

1. Decreased saliva- dry mouth
2. Increased blood osmotic pressure
3. Decreased blood volume & blood pressure

Question 10

What happens when there is a decrease in blood pressure?

Answer 10

This stimulates renin to be released from the kidneys

Question 11

What happens when there is an increase in renin?

Answer 11

Increased Angiotensin II production

Question 12

What does Angiotensin II then stimulate?

Answer 12

Stimulates the thirst center in the hypothalamus

Question 13

What is the main way to regulate body fluid gain?

Answer 13

By adjusting the volume of preformed water intake; drinking more or less fluids.

Question 14

What are three hormones that regulate fluid loss?

Answer 14

ADH, Aldosterone, ANP

Question 15

Where does the hormone ANP come from?

Answer 15

The atria of the heart

Question 16

An increase in blood osmolarity or a decrease in blood volume stimulates the release of what hormone?

Answer 16

ADH

Question 17

When does ANP release from the heart?

Answer 17

In response to abnormal stretching of the atrial walls

caused by elevated blood pressure or an increase in blood volume.

Question 18

What does the atrial natriuretic peptide hormone do (from the name)?

Answer 18

Eliminates sodium through the urine

Question 19

Where is ADH produced and secreted?

Answer 19

Produced: hypothalamus
Secreted: posterior pituitary

Question 20

What do osmoreceptors do?

Answer 20

Monitor the osmotic concentration of the ECF.

Question 21

What is the relationship between the rate of ADH release and osmolarity?

Answer 21

Direct relationship (inc osmolarity, inc ADH release)

Question 22

What are the effects of an increased release of ADH

Answer 22

1. Stimulates water retention in the kidneys, reducing diuresis and concentrating the urine
2. Stimulates the thirst center to promote drinking

Question 23

What happens to the plasma osmolarity during dehydration?

Answer 23

Increased

Question 24

What happens to the plasma osmolarity during overhydration?

Answer 24

Decreased

Question 25

T/F: Collecting ducts are water permeable and determine the osmolality of the excreted urine.

Answer 25

True

Question 26

What happens when ADH is absent in the collecting ducts?

Answer 26

They will be relatively impermeable to water, produce diluted urine.

Question 27

What two results may occur due to hypotonicity, or poor renal function?

Answer 27

1. Water intoxication | 2. Circulatory shock

Question 28

Which hormone directly affects sodium absorption in the kidneys?

Answer 28

Aldosterone

Question 29

T/F: The higher the plasma aldosterone | concentration, the less efficiently the kidneys will conserve sodium.

Answer 29

False, more efficiently

Question 30

Aldosterone release occurs in response to activation of the renin-angiotensin system by which 3 ways?

Answer 30

1. Decrease in blood pressure 2. Increase in ECF osmolarity 3. Increase in K+ levels

Question 31

Is secretion of aldosterone directly influenced by Na+ concentration in the plasma?

Answer 31

No

Question 32

What is the key role of potassium in the cell?

Answer 32

Establish the resting membrane potential, and in the repolarization phase of action potentials in nervous and muscle tissue.

Question 33

What hormone controls the plasma levels of K+?

Answer 33

Aldosterone

Question 34

How does ANP reduce blood pressure and volume?

Answer 34

1. Increasing water loss at the kidneys. 2. Reducing thirst. 3. Blocking the release of ADH. 4. Stimulating peripheral vasodilation.

Question 35

What happens when blood pressure and volume decrease?

Answer 35

The stretch on the atrial walls is removed, and ANP secretion decreases.