Fluid, Electrolyte and Acid-Base Dynamics Human Anatomy and Physiology II Oklahoma City Community College Dennis Anderson
Concentration of Solutions • Percent Salt • 0.9% NaCl • Milliosmoles • 300 milliosmoles/Liter • Milliequivalents • 325 milliequivalents/Liter
0.9% NaCl Hypertonic Solution 3% NaCl
0.9% NaCl Hypotonic Solution 0.5% NaCl
0.9% NaCl Isotonic Solution 0.9% NaCl
300 mosm 310 mosm Which Way Will Fluid Move?
Application Problem 1 • Michael has recently started working outdoors in the hot weather to earn money for his tuition. After a few days he experienced headaches, low blood pressure and a rapid heart rate. His blood sodium was down to 125 meq/L. The normal is 144 meq/L. How do you explain this?
Answer to Problem 1 • Michael lost sodium by perspiration. The low sodium in his blood allowed fluid to move into cells by osmosis. Lack of fluid lowered his blood pressure to give him a headache. The increased heart rate was his bodies way of trying to increase blood pressure.
Application Problem 2 • Frank has hypertension. His doctor has advised Frank eat a low salt diet. Frank consumed a lot of salt the day before his last checkup. His blood pressure was up. Why?
Answer to Problem 2 • The extra salt Frank ate made his blood hypertonic. Hypertonic blood will attract fluids from body cells by osmosis.
Electrolyte vrs. Nonelectrolyte NaCl Na+ + Cl- Glucose Glucose
Carbonic Acid Carbon Dioxide and Acid CO2 + H2O H2CO3H++ HCO3-
More Carbon Dioxide = More Acid = Lower pH • Breathing slower will retain CO2 , pH will • decrease (more acid) • Breathing faster will eliminate more CO2 pH will • increase (less acid)
Blood pH Drops to 7.3How does the body compensate? • Breath faster to get rid of carbon dioxide • eliminates acid
Blood pH Increases to 7.45How does the body compensate? • Breath slower to retain more carbon dioxide • retains more acid
John is Taking Narcotics for PainThe narcotics have depressed his breathing rate. What will happen to his blood pH? • pH will decrease because he will retain excess carbon dioxide which will increase the amount of acid in the blood
Buffers Regulate pH • Chemicals that resist changes in pH • Prevent large pH changes when an acid or base is added
Strong Acid • Acid that releases many hydrogen ions • HCl
Weak Acid • Acid that releases only a few hydrogen ions • Carbonic Acid
H2CO3 + NaCl HCl + NaOH Strong Acid Base Weak Acid Salt Buffers Change Strong Acids to Weak Acids
Acidosis • pH below 7.35 • Depresses the nervous system • coma
Alkalosis • pH above 7.45 • Overexcites the nervous system • convulsions