Lecture 27

Question 1

What are the seven key electrolytes?

Answer 1

Na+, K+, Cl-, Ca2+, HPO4²-, Mg2+, HCO3-

Question 2

Major extracellular cation?

Answer 2

Sodium (Na+)

Question 3

Major intracellular cation?

Answer 3

Potassium (K+)

Question 4

Major extracellular anion?

Answer 4

Chloride (Cl-)

Question 5

Role of sodium in fluid balance?

Answer 5

Creates ~50% of osmotic pressure gradient between ICF and ECF.

Question 6

Where is sodium filtered and reabsorbed?

Answer 6

Filtered at glomerulus; mostly reabsorbed in proximal tubule.

Question 7

Hormones regulating Na+/K+ exchange?

Answer 7

Aldosterone and angiotensin II.

Question 8

Aldosterone effect on Na+/K+?

Answer 8

Increases Na+ reabsorption and K+ secretion.

Question 9

Potassium’s main function?

Answer 9

Helps re-establish resting membrane potential after depolarization.

Question 10

Why does K+ have little osmotic effect?

Answer 10

Low extracellular levels maintained by Na+/K+ pumps.

Question 11

Role of chloride?

Answer 11

Balances cations in ECF; follows Na+ movement.

Question 12

Definition of chloride shift?

Answer 12

Exchange of Cl- and HCO3- in RBCs to maintain electrical neutrality.

Question 13

Calcium roles?

Answer 13

Muscle contraction, nerve transmission, enzyme activity, blood clotting.

Question 14

Hormone increasing blood Ca2+?

Answer 14

Parathyroid hormone (PTH).

Question 15

Hormone decreasing blood Ca2+?

Answer 15

Calcitonin.

Question 16

Active vitamin D form?

Answer 16

Calcitriol.

Question 17

Phosphate roles?

Answer 17

Buffers ICF, part of ATP, nucleotides, membranes.

Question 18

Magnesium roles?

Answer 18

Enzyme activation, sodium pump function, neuromuscular activity.

Question 19

Bicarbonate role?

Answer 19

Major buffer maintaining blood pH.

Question 20

Reaction forming bicarbonate?

Answer 20

CO2 + H2O → H2CO3 → H+ + HCO3-.

Question 21

Normal blood pH range?

Answer 21

7.35–7.45.

Question 22

Definition of a buffer?

Answer 22

Chemical system that resists major pH changes by absorbing H+ or OH-.

Question 23

Three main buffer systems?

Answer 23

Phosphate, protein, bicarbonate-carbonic acid.

Question 24

Phosphate buffer components?

Answer 24

HPO4²- (weak base) and H2PO4- (weak acid).

Question 25

Most abundant buffer system?

Answer 25

Protein buffer system.

Question 26

Most important protein buffer?

Answer 26

Hemoglobin.

Question 27

Bicarbonate:carbonic acid ratio in blood?

Answer 27

20:1 when pH is normal.

Question 28

How lungs regulate pH?

Answer 28

Alter CO2 exhalation to increase/decrease carbonic acid.

Question 29

How kidneys regulate pH?

Answer 29

Excrete H+ and reabsorb or generate new HCO3-.

Question 30

Respiratory acidosis cause?

Answer 30

Hypoventilation → ↑CO2 → ↓pH.

Question 31

Respiratory acidosis compensation?

Answer 31

Kidneys retain HCO3- and secrete H+.

Question 32

Respiratory alkalosis cause?

Answer 32

Hyperventilation → ↓CO2 → ↑pH.

Question 33

Respiratory alkalosis compensation?

Answer 33

Kidneys excrete HCO3- and retain H+.

Question 34

Metabolic acidosis cause?

Answer 34

Loss of HCO3- or excess acids (diarrhea, ketoacids).

Question 35

Metabolic acidosis compensation?

Answer 35

Hyperventilation → ↓CO2.

Question 36

Metabolic alkalosis cause?

Answer 36

Loss of acid (vomiting) or base ingestion.

Question 37

Metabolic alkalosis compensation?

Answer 37

Hypoventilation → ↑CO2.

Question 38

Complete compensation?

Answer 38

pH restored to 7.35–7.45.

Question 39

Partial compensation?

Answer 39

pH improves but remains outside normal range.