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Role of Kidney in homeostasis, Causes of Hypercalcemia: neoplasms,…
Role of Kidney in homeostasis
Regulation
Electrolyte Balance
Sodium- major ECF ion; maintains oncotic pressure; involved in acid-base balance; transmission of nerve impulses
Maintained by Aldosterone, ADH and ANP; majority of Na absorption takes place in proximal tubule and some in distal tubule
Causes of Hypernatremia: Excessive Na intake, water deprivation, low ADH, diarrhea; S/sxs: weakness, lethargy, agitation, edema, increased thirst
Causes of Hyponatremia: excessive sweating, water intake, vomiting and diarrhea, diuretics, hormonal imbalance, renal failure; S/Sxs: anorexia, nausea, lethargy, weakness, confusion, seizures
Potassium -major ICF ion- maintains membrane potential of nerve and muscles; influenced by acid-base balance in the body; aids in release of energy from carbohydrates, proteins and fats
65% reabsorbed in proximal tubule; regulated by aldosterone; secretion is linked to Na and H ions
Causes of Hypo-K: diarrhea, diuretic drugs, excessive aldosterone or glucocorticoids, decreased dietary intake, insulin; S/sx: cardiac dysrhythmias, cardiac arrest, fatigue, muscle weakness, paresthesia, anorexia, shallow respirations; polyuria
Causes of Hyper-K:renal failure, aldosterone deficit, K sparing diuretics, traumatic injuries, severe acidosis; S/sxs: dysrhythmias, cardiac arrest, muscle weakness, fatigue, nausea,
paresthesia
Phosphate ions- for bone and teeth mineralization, involved in energy metabolic processes, buffer system in acid-base balance
regulated by PTH along with Ca
Causes of Hypophosphatemia: malabsorption, diarrhea, excessive antacid use, hyperparathyroidism; S/sxs: impaired neurologic functions
Causes of Hyperphosphatemia: renal failure, chemotherapy; S/Sxs: similar to hypocalcemia
Chloride- major ECF anion, tends to follow Na because of the electrical charge on these ions, helps maintain body fluids
regulated by the kidneys, reabsorbed in the tubules where it follows water and Na
Causes of Hypochloremia: vomiting, excessive perspiration, diarrhea, aldosterone deficiency. S/sxs: spasm, tetany, shallow respiration
Causes of Hyperchloremia: excessive intake of NaCl, dehydration, renal failure, aldosterone excess. S/sxs: weakness, lethargy, deep rapid respiration
Calcium (Ca) is involved in nerve and muscle conduction, blood clotting, building bones and teeth
Regulated by PTH and Vit D; PTH raises Ca by bone breakdown, pTH acts on kidneys to convert Vit D to its active form
Causes of Hypocalcemia: hypoparathyroidism, malabsorption, low albumin, high pH;S/sxs: tetany, tingling, confusion, arrhythmias
Acid-Base Balance
HCO3 + H--> H2CO3 -->H2O + CO2 cell enzymes can only function within pH 7.35-7.45
kidneys regulate pH by excretion of excess H+ in the urine or conserving bicarbonate ion
In metabolic acidosis, pH becomes less than 7.35. Kidneys compensate by secreting H+ and reabsorbing bicarbonate in the proximal and distal tubule
Causes: diabetic ketoacidosis, starvation, diarrhea, drugs, kidney failure, poisoning, dehydration, lactic acidosis.
S/sxs: rapid breathing, confusion, death
In metabolic alkalosis, pH becomes more than 7.40 and kidneys respond by excreting excess bicarbonate through the urine to conserve H+
Causes: Vomiting, hypovolemia, use of diuretics, excess antacid intake. S/sxs: slow shallow respiration, confusion, spams, nausea
Body water volume and BP
Kidneys regulate BP and fluid volume by reabsorbing Na and water
Maintained by ADH, aldosterone and ANP
RAA system: Angiotensin II promotes reabsorption of Na in the proximal tubules and also a vasoconstrictor. and plasma aldosterone promoting arterial vasoconstriction. Aldosterone promotes reabsorption of Na and Cl in collecting duct. These processes increase blood volume and BP
ANP is released from cardiac cells to lower BP by increasing renal excretion of salt and water, and vasodilation
ADH secretion is stimulated by low BP or blood volume. It acts on the distal convoluted tubule and collecting duct to increase water reabsorption
Production of Hormone
Activation of Vitamin D
kidneys convert inactive vit. D to its active form called Calcitriol; together with PTH work to increase plasma Calcium
renal diseases lead to bone diseases
Production of Erythropoietin
Stimulates RBC production,
stimulated by hypoxia
renal diseases lead to anemia
Production of Renin
helps to regulate fluid volume and BP
via the RAA system
renal diseases can lead to edema and hypertension, electrolyte imbalances, among other things
Excretion of wastes
Kidneys play a significant role in waste excretion in the form of urine; wastes include urea, creatinine, drugs, ammonnia, bilirubin, uric acid
accumulation of these wastes lead to toxic effects to the body
Causes of Hypercalcemia: neoplasms, hyperparathyroidism, immobility, increased Ca intake, milk alkali syndrome;S/Sxs: lethargy, apathy, constipation, kidney stones, arrythmias
Potassium
Calcium
Sodium
Phosphate
Chloride
Silva M. Cortez
NEPH-510-096
Stella Salamat - Instructor