I). Electrolytes

A). Definition

Electrolyte:

B). Electrolyte Balance:

 

C). Controlled By

1). Hormones:

i). aldosterone Þ

 

ii). Parathyroid hormone Þ

II). Acid-Base Balance

A). Sources of H+

1). Aerobic respiration

CO2 + H2O Þ H2CO3 (carbonic acid)

H2CO3 Þ H+ + HCO3- (bicarbonate)

2). Anaerobic respiration

3). Incomplete oxidation of fatty acids

4). Oxidation of amino acids

5). Break down of phophoproteins and nucleic acids

 

B). First line of defense against shift in pH

Acid Base Buffer Systems

1). Bicarbonate buffer system

i). HCO3- acts as a weak base

 acidic

H+ + HCO3- Þ H2CO3

ii). H2CO3 acts as a weak acid

basic

H2CO3 Þ H+ + HCO3-

2). Phosphate Buffer System

 

3). Protein Buffer System

C). Secondary line of defense

 

1). Renal Excretion of H+

H+  +   NH3 Þ NH4+

(H+) + (ammonia) Þ (ammonium ion)

 

2). Respiratory Excretion of CO2

Respiratory center responds to the  H+.

CO2 + H2O Þ H2CO3 (carbonic acid)

H2CO3 Þ H+ + HCO3- (bicarbonate)

 

 equilibrium

Thus if pH is low (acidic) breathing can increase

CO2 + H2O ← H2CO3 ← H+ + HCO3-

Thus removing H+

 if pH is high (basic) breathing can decrease

Thus adding H+