Week 11

• Osmolarity: amount of solute per litre of solvent
• Osmolality: amount of solute per kg of solvent
• osmolality is easier to measure than osmolarity
• Oncotic pressure pulls in while hydrostatic pressure pushes out
• Lack of H2O leads to a switch to anaerobic metabolism
• ICF is about 2/3 of the water content while ECF makes up the rest
• ECF contains interstitial fluid(80%) and plasma (20%).
• Majority of sweating occurs insensibly and we are not conscious of it at all
• ADH increases H20 reabsorption at the collecting ducts and DCT of the kidney
• These signals stimulate thirst: dry mouth, increase in osmolarity and decrease in BP and blood volume
• Blood composition depends on 3 factors: diet, cellular metabolism and urine output
• Electrolytes are ions that conduct electricity in an aqueous solution
• The 2 main solutes in the ECF are the Na+ and Cl-
• Most excess body water and solutes are eliminated through urine
• ICF Cations are: K+, Ca+, Mg+(order of most to least common)
• The only anion in the ICF is PO4-
• Electrolytes are mostly obtained through ingestion of water
• Too few Na+ molecules can cause edema
• ECF anions are Cl- and HCO3-
• Na+ is the main electrolyte responsible for osmotic water flow
• 80% of Na+ is reabsorbed early in the PCT
• Aldosterone stimulates Na+ retention and K+ excretion
• Hypernatremia: gaining more Na+ than H20 or vice-versa
• Signs and symptoms of hypernatremia: strong thirst, fever, restless, edema, decreased urine output, dry skin, confusion and seizure/coma/death
• hyponatremia: loss of Na+ loss or gaining excessive H2O.
• Signs and symptoms of hyponatremia: stupor, Abdomen cramping, lethargy, loss of urine and appetite, shallow respirations and seizure/coma/death
• alkalosis is often associated with hypokalemia while acidosis is associated with hyperkalemia
• Hyperchloremia occurs due to losses of bicarbonate in lower GI tract. S&S include: weakness, kussmaul respirations and decreased LOCs which is a late sign
• Cl- mostly exists as NaCl and its measured in blood, urine and sweat
• Hypochloremia occurs due to vomiting, diarrhea, diaphoresis, pyrexia or diabetic ketoacidosis. S&S include tetany/muscle excitability, bradypnea and hypotension
• Calcium is the most abundant mineral in the body
• Kidneys activate vitamin D by converting it to calcitriol
• Calcium has many fxns: ICF/ECF fluid balance, clotting, nerve conduction, cardiac fxn, skeletal muscles and bone formation.
• Hypercalcemia is due to hyperparathyroidism, malignancy(cancer) and thiazide diuretics
• Too much Ca+ leads to faster conduction in the heart which leads to a shortened QT segment. This could cause a possible R on T phenomenon
• Hypercalcemia causes these GI symptoms: anorexia, nausea, constipation
• Hypercalcemia causes these renal symptoms: kidney stones, polyuria and polydipsia(excessive thirst)
• Hypercalcemia alters LOAs in these ways: depression, confusion, delirium and can cause comas as well
• Hypocalcemia can cause paresthesia, facial/extremity spasm, stridor (due to laryngeal spasm) and increase clotting time
• Magnesium aids in nerve and muscle fxn, immunity, bone density, blood glucose levels and protein and energy production