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

Osmosis

Osmosis

Hypertonic Solution

0.9% NaCl

3% NaCl

Cells Crenate in a Hypertonic Solution

Hypotonic Solution

0.9% NaCl

0.5% NaCl

Cells in a Hypotonic Solution Swell and May Lyse

Isotonic Solution

0.9% NaCl

0.9% NaCl

310 mosm

300 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

Aldosterone• Hormone secreted

from the adrenal cortex

• Stimulates kidneys– Retain sodium

• Retain water

– Secrete potassium

Estrogen

• Female hormone from the ovaries– Similar to aldosterone

• Stimulates the kidneys to retain sodium

• Increases fluid retention

Cortisol

• Hormone from the adrenal cortex

• Converts lipids and protein to glucose

• Depress inflammation

• Stimulates the kidneys to retain sodium

• Increases fluid retention – Elevated levels cause edema

Antidiuretic HormoneADH

ADH

Hypertonic Interstitial Fluid

Collecting Duct

H2O

Urine

Calcitonin

Calcium

Estrogen

Calcium

Parathormone

Calcium

Blood pH = 7.4(7.35-7.45)

Blood pH regulated by

1. Kidneys

2. Lungs

3. Buffers in blood

H+ Secreted HCO3

- Rebsorbed

Blood

Kidney Nephron

HCO3-

H+

Urine

Kidneys Regulate pH

• Excreting excess hydrogen ions, retain bicarbonate– if pH is too low

• Retaining hydrogen ions, excrete bicarbonate– if pH is too high

Lungs Regulate pH

• Breath faster to get rid of excess carbon dioxide if pH is too low– Carbon dioxide forms carbonic acid in the

blood

• Breath slower to retain carbon dioxide if pH is too high

Carbon Dioxide and Acid

CO2 + H2O H2CO3 H+ + HCO3-

Carbonic Acid

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

Buffers Change Strong Acids to Weak Acids

HCl + NaOHStrong Acid

BaseH2CO3+ NaClWeak Acid Salt

Bicarbonate: Carbonic Acid

• 20:1 = pH 7.4

• 21:1 = pH more than 7.4

• 19:1 = pH less than 7.4

Acidosis

• pH below 7.35

• Depresses the nervous system– coma

Alkalosis

• pH above 7.45

• Overexcites the nervous system– convulsions

Respiratory Acidosis

• Any condition that impairs breathing

• Carbon dioxide increases in blood

• Excess carbon dioxide lowers pH

Respiratory Alkalosis

• Hyperventilation

• Carbon dioxide decreases in blood

• Low carbon dioxide raises pH

Metabolic Acidosis

• Not caused by breathing or carbon dioxide imbalance

• Excess acid in blood– Renal disease, Diabetes or Starvation

• Deficiency of bicarbonate in blood– Diarrhea

Metabolic Alkalosis

• Not caused by breathing or carbon dioxide imbalance

• Deficiency of acid in the blood– Vomiting, Diuretics

• Excess bicarbonate in the blood– Ingesting sodium bicarbonate

Sodium

• Attracts water into the ECF

• Nerve impulse

• Muscle contractions

Hypernatremia

• Excess sodium in the blood

• Hypertension

• Muscle twitching

• Mental confusion

• Coma

Hyponatremia

• Deficiency of sodium in the blood

• Hypotension

• tachycardia

• Muscle weakness

Potassium

• Attracts water into the ICF

• Nerve impulse

• Muscle contractions

Hyperkalemia

• Excess potassium in the blood

• Cardiac arrhythmias and cardiac arrest

• Elevated T wave

• Muscle weakness

Hypokalemia

• Deficiency of potassium in the blood

• Cardiac arrhythmias and cardiac arrest

• Flatened T wave

• Muscle weakness

Calcium

• Most in bones and teeth

• Blood clotting

• Nerve impulse

• Muscle contraction

Hypercalcemia

• Excess calcium in the blood

• Kidney stones

• Bone pain

• Cardiac arrhythmias

Hypocalcemia

• Deficiency of calcium in the blood

• Tetany

• Weak heart muscle

• Increased clotting time

Aldosteronism

• Excess production of aldosterone

• Elevated sodium levels

• Depressed potassium levels

• Hypertension

Addison’s Disease• Hyposecretion of the Adrenal Cortex

– Hyposecretion of Aldosterone– Hyposecretion of Glucocorticoids

• Hormones that convert protein sugar

• Hypotension– Sodium deficiency

• Low blood sugar– Not enough glucocorticoids

Cushing’s Syndrome• Excess glucocorticoids

– Tumor of adrenal gland– Side effect of steroid drugs

• cortisone

• Hyperglycemia• Fat accumulation

– Abdomen– Back of neck (buffalo hump)

Insulin

Glucose

Cell

Blood

Diabetes Mellites• Hyposecretion or hypoactivity of insulin• Hyperglycemia• Glycosurea• Polyurea• Thirst• Body burns more fat

– Ketone bodies• Metabolic Acidosis

• Fat deposits in arteries– Heart Attack, Stroke, Poor Circulation

Antidiuretic HormoneADH

ADH

Hypertonic Interstitial Fluid

Collecting Duct

H2O

Urine

Diabetes Insipidus

• Hyposecretion of ADH

• Increased urine volume

THE END