Chapter 27 cont. Regulation of Water Balance

Question 1

Regulation of Water Balance (how much we gain and lose)

Answer 1

• about 2.5 liters of water gained per day

- about 2.5 liters of water lost per day

Question 2

If water loss > water gain

Answer 2

Dehydration Occurs (osmolarity increases)

Question 3

If water gain > water loss

Answer 3

Excess water in body (osmolarity decreases)

Question 4

Where is the Thirst Center located?

Answer 4

Hypothalamus

Question 5

Thirst Center Response to increased osmolarity (dehydration)

Answer 5

• Induces thirst

- Releases ADH

Question 6

Thirst Center response to decreased osmolarity (excess of water)

Answer 6

• inhibits thirst

- inhibits ADH release

Question 7

Na+ is regulated by?

Answer 7

tubular reabsorption

• High BP, High Blood volume —> triggers ANP release—> increases Na+ and water excretion–> results in lower BP + Blood volume
• Low BP, Low blood volume—> triggers Aldosterone release—> increases Na+ reabsorption—> results in higher BP blood volume

Question 8

K+ is regulated by?

Answer 8

tubular secretion

• High blood K+ —> triggers an increase in secretion of K+ into urine—> results in lowering the blood K+
• Low blood K+ –> inhibits secretion of K+ into urine –> results in conserving the K+ in blood

Question 9

pH

Answer 9

a measure of the H+ ion concentration in solution

Question 10

Normal pH of fluid compartments

Answer 10

Arterial Plasma- 7.4
Venous Plasma- 7.35
Intracellular Fluid (ICF)- 7.0 (neutral)

Question 11

pH imbalances of arterial plasma

Answer 11

1. Alkalosis- pH > 7.45

2. Physiological Acidosis- pH < 7.35

Question 12

3 mechanisms to regulate acid-base balance of the blood

Answer 12

1. Buffers
2. Respiratory Compensation
3. Renal Compensation

Question 13

Buffers

Answer 13

weak acids or weak bases which minimize changes in pH

Question 14

Acids

Answer 14

substances that release H+ ions in solution

Question 15

Bases

Answer 15

substances that remove H+ ions from solution

Question 16

Buffers in the Fluid Compartments

Answer 16

1. ECF- Carbonic acid-bicarbonate buffer
2. Urine + ICF- Phosphate Buffer
3. ICF- Protein Buffer

Question 17

Carbonic acid-bicarbonate Buffer

Answer 17

-In Extracellular Fluid (ECF)

• Weak Acid: Carbonic Acid (H2CO3)
• Weak Base: Bicarbonate (HCO3- 1)

Question 18

Phosphate Buffer

Answer 18

-In Urine + Intracellular Fluid (ICF)

• Weak Acid: (H2PO4- 1) dihydrogen phosphate
• Weak Base: (HPO4- 2) monohydrogen phosphate

Question 19

Protein Buffer

Answer 19

-In intracellular fluid (ICF)

• Weak Acid: Aspartic acid + Glutamic Acid
• Weak Base: Lysine, Arginine, + Histidine

Question 20

If pH is too low, the weak _____ removes H+ from solution, results in _____

Answer 20

• Base

- raising the pH

Question 21

If the pH is too high, the weak ____ releases H+ into solution, results in _____

Answer 21

• Acid

- lowering the pH

Question 22

Respiratory Compensation

Answer 22

correcting blood pH imbalances by changing breathing

• If blood < 7.35, respiratory compensation by Hyperventilation —> results in raising pH of blood
• If blood pH > 7.45, respiratory compensation by slow, shallow breathing –> results in lowering the pH of blood

Question 23

Respiratory Compensation is explained by this chemical reaction

Answer 23

CO2 + H2O H2Co3 H+ HCO3- 1

Question 24

Renal Compensation

Answer 24

kidneys correct for pH imbalances

• If imbalance is acidosis, then new bicarbonate (HCO3- 1) is reabsorbed –> results in raising blood pH
• If imbalance is alkalosis, then H+ ions are reabsorbed –> results in lowering the pH of blood