Water Movement through Semi-Permeable Membranes Quiz

Water Movement and Composition

• Water moves through semi-permeable membranes by osmosis
• Brain and kidney have the highest proportion of water
• Teeth have the lowest proportion of water

Fluids in the Body

• Intracellular fluid (ICF): all fluid enclosed by plasma membranes, 60% of total water in humans, volume is stable
• Extracellular fluid (ECF): all fluid surrounding cells, 2 possible areas:
  • Plasma in blood
  • Interstitial fluid (IF) and other fluids like cerebrospinal fluid, lymph, and others (5%)

Sodium-Potassium Pump

• Uses energy provided by ATP to force sodium out of the cell and bring potassium into the cell
• Balances the cell to allow for action potential

Hydrostatic Pressure

• Force exerted by fluid against a wall, which causes movement between compartments
• Important in blood vessels and nephrons

Water Balance

• Take in about 2500ml of fluid each day and generate 230ml metabolically
• Same amount leaves the body each day through urination, skin evaporation, and expelled from the lungs
• Diuresis: production of excess urine, begins about 30 minutes after drinking a lot of water, normal urine production reestablishes in about 3 hours

ADH Production

• Dehydration triggers increased ADH production to conserve water
• ADH helps regulate water balance in the body

Electrolytes

• 6 most important electrolytes: sodium, potassium, chloride, bicarbonate, calcium, and phosphate

Electrolyte Imbalances

• Hyponatremia: low sodium levels, associated with excess water accumulation or injection
• Hypernatremia: high sodium levels, can result from water loss or imbalance of ADH and aldosterone
• Hypokalemia: low potassium levels, may be due to starvation, vomiting, diarrhea, or alkalosis
• Hyperkalemia: high potassium levels, can impair nervous system, muscles, and heart
• Hypochloremia: low chloride levels, due to defective renal tubular absorption, vomiting, diarrhea, and metabolic acidosis
• Hyperchloremia: high chloride levels, due to dehydration, salt intake, drinking sea water, aspirin intoxication, congestive heart failure, and cystic fibrosis
• Hypocalcemia: low calcium levels, may follow removal of thyroid gland
• Hypercalcemia: high calcium levels, seen in hyperparathyroidism and other malignancies
• Hypophosphatemia: low phosphate levels, due to heavy use of antacid, during alcohol withdrawal, and malnourishment
• Hyperphosphatemia: high phosphate levels, due to decreased renal function or acute lymphocytic leukemia

pH Regulation

• Respiratory tract regulates pH by exhaling CO2
• Renal system regulates pH by excreting hydrogen ions and conserving bicarbonate

Acid-Base Imbalances

• Hypercapnia: high blood CO2 levels, can be due to pneumonia, congestive heart failure, or hypoventilation
• Hypocapnia: low blood CO2 levels, due to hyperventilation, elevated room temperatures, fever, or hysteria
• Acidosis: pH below 7.35
• Alkalosis: pH above 7.45