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

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

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

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 Hormone ADH ADH Hypertonic Interstitial Fluid Collecting Duct H2OH2O Urine

Calcitonin Calcium

Estrogen Calcium

Parathormone Calcium

Blood pH = 7.4 ( ) Blood pH regulated by 1. Kidneys 2. Lungs 3. Buffers in blood

H + Secreted HCO 3 - Rebsorbed Blood Kidney Nephron HCO 3 - H+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 CO 2 + H 2 O H 2 CO 3 H + + HCO 3 - Carbonic Acid

More Carbon Dioxide = More Acid = Lower pH Breathing slower will retain CO 2, pH will –decrease (more acid) Breathing faster will eliminate more CO 2 pH will –increase (less acid)

Blood pH Drops to 7.3 How does the body compensate? Breath faster to get rid of carbon dioxide –eliminates acid

Blood pH Increases to 7.45 How does the body compensate? Breath slower to retain more carbon dioxide –retains more acid

John is Taking Narcotics for Pain The 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 + NaOH Strong Acid Base H 2 CO 3 + NaCl Weak AcidSalt

Bicarbonate: Carbonic Acid 20:1 = pH :1 = pH more than :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 Hormone ADH ADH Hypertonic Interstitial Fluid Collecting Duct H2OH2O Urine

Diabetes Insipidus Hyposecretion of ADH Increased urine volume

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