7. Acid-Base (pH)

Question 1

Water in the body - Intracellular fluid

Answer 1

1) Fluid inside the cells

2) About 60% of fluids in the body
a) Example: 150-pound male = 25 liters

Question 2

Extracellular fluid (4)

Answer 2

1) Fluid outside of the cells
2) About 40% of fluids in the body

3) Plasma
a) Fluid portion of blood
b) About 8% of total body water

4) Interstitial fluid
a) Fluid in the microscopic spaces between cells
b) About 32% of water

Question 3

Acid-Base balance - pH Scale (5)

Answer 3

1) Measurement of concentration of hydrogen ions

2) Ranges from 0-14

3) 0 = most acidic

4) 7 = neutral

14 = most alkaline (basic)

Question 4

Acids (3)

Answer 4

1) Higher concentration of H+ ions present in a solution
a) lowers pH (increasing acidity)

2) Strong acids dissolved in water produce H+ ions
a) Makes solution more acidic
b) Lowers the pH

3) Weak acids do not significantly contribute to the pH
a) H+ is tightly bound and cannot dissociate to become free H+
Example: Carbonic Acid (H2CO3)

Question 5

Bases (2)

Answer 5

1) Lower concentration of H+ ions present in a solution
a) Increases pH (more alkaline)

2) Bases dissolved in water produce OH- ions
a) Combines with H+ ions
b) Raise the pH

Question 6

Importance of Homeostasis of pH (2)

Answer 6

1) Proteins depend on a narrow range of pH

2) Enzymatic function
a) Specialized proteins that control all metabolic reactions

Question 7

Normal pH of Blood (3)

Answer 7

1) Normal arterial blood: 7.35-7.45

2) Alkalosis = above 7.45

3) Acidosis = below 7.35

Question 8

Cellular Metabolism (2)

Answer 8

1) Set of chemical reactions inside a cell to maintain life

2) Principal method through which acids are entering the body (need to be able to balance and excrete them)

Question 9

Homeostatic Regulators of the body visual

Answer 9

Question 10

Chemical Buffer Systems - Ions (2)

Answer 10

1) Anion = negatively charged ions
a) Bicarbonate ion (HCO3)

2) Cation = positively charged ion
a) Ammonium (NH4+)

Question 11

Chemical Buffer Systems - Action of Mechanism (4)

Answer 11

1) Weak acid and its anion OR weak base and its cation

2) Act to minimize pH changes

3) Weak acid anion or weak base
a) Reacts with free H+ in the acid to bind on it
b) Preventing it from lowering pH

4) Weak acid or weak base cation
a) Reacts with OH to bind to it
b) Preventing it from raising pH

Question 12

Chemical Buffer Systems visual

Answer 12

Question 13

Respiratory Control Mechanism - Brainstem (Medulla) (4)

Answer 13

1) Has a respiratory center with chemoreceptors

2) Chemoreceptors detect the level of CO2 in the blood

3) CO2 and O2 removed added under control of the respiratory center

4) Keeps pressure off CO2, in the blood between 35-45 mmHg

Question 14

Respiratory Control Mechanism - Chemical Reactions (2)

Answer 14

1) In red blood cells, CO2 reacts reversibly with water to form carbonic acid (H2CO3)
a) CO2 +H2O yields H2CO3

2) Carbonic acid: dissociates in water to form H+ and bicarbonate ions
a) H2CO3 yields H+ + HCO3-
b) Bicarbonate is the main form in which CO2 is transported in the blood plasma

3) Forms series of equilibrium reactions:
a) CO2 +H2O yields H2CO3 yields H+ + HCO3
b) Carbon dioxide plus water yields carbonic acid yields hydrogen ions and bicarbonate ions

Question 15

When blood pH falls (becomes more acidic) (4)

Answer 15

CO2 +H2O yields H2CO3 yields H+ + HCO3

1) Respiratory center stimulated, causing increased respiratory rates

2) Increase in respiratory rate to remove CO2 from blood

3) Removal of CO2 uses up H+

4) pH rises, restores correct blood pH

Question 16

When blood pH rises (becomes more alkaline)

Answer 16

CO2 +H2O yields H2CO3 yields H+ + HCO3

1) Respiratory center decreased, causing decreased respiratory rate

2) Decrease in respiratory rate to increase CO2 in the blood

3) Accumulation of CO2 forms more H+

4) pH falls, restores correct blood pH

Question 17

Malfunctions (2)

Answer 17

1) Respiratory acidosis (pH < 7.35)
a) CO2 retention
b) Usually hypoventilation (too little)
c) Body cannot remove enough CO2 from body

2) Respiratory alkalosis (pH > 7.45)
a) CO2 removal
b) Usually hyperventilation (panic attack)
c) Reduction of arterial levels of CO2