Fluid, Electrolyte and Acid-Base Dynamics

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Fluid, Electrolyte and Acid-Base Dynamics

• Human Anatomy and Physiology II
• Oklahoma City Community College

Dennis Anderson
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Concentration of Solutions

• Percent Salt
• 0.9 NaCl
• Milliosmoles
• 300 milliosmoles/Liter
• Milliequivalents
• 325 milliequivalents/Liter

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Osmosis
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Osmosis
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Hypertonic Solution
3 NaCl
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Cells Crenate in a Hypertonic Solution
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Hypotonic Solution
0.5 NaCl
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Cells in a Hypotonic Solution Swell and May Lyse
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Isotonic Solution
0.9 NaCl
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Which Way Will Fluid Move?
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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?

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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.

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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?

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Answer to Problem 2

• The extra salt Frank ate made his blood
  hypertonic. Hypertonic blood will attract fluids
  from body cells by osmosis.

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Electrolyte vrs. Nonelectrolyte
NaCl Na Cl-
Glucose
Glucose
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Carbon Dioxide and Acid
CO2 H2O H2CO3 H HCO3-
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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)

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Blood pH Drops to 7.3How does the body
compensate?

• Breath faster to get rid of carbon dioxide
• eliminates acid

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Blood pH Increases to 7.45How does the body
compensate?

• Breath slower to retain more carbon dioxide
• retains more acid

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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

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Buffers Regulate pH

• Chemicals that resist changes in pH
• Prevent large pH changes when an acid or base is
  added

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Strong Acid

• Acid that releases many hydrogen ions
• HCl

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Weak Acid

• Acid that releases only a few hydrogen ions
• Carbonic Acid

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Buffers Change Strong Acids to Weak Acids
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Acidosis

• pH below 7.35
• Depresses the nervous system
• coma

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Alkalosis

• pH above 7.45
• Overexcites the nervous system
• convulsions