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Fluid and Electrolyte Imbalances. Fluid and electrolytes in the body Fluid volume changes due to pressure Hormonal regulation of fluid balance Electrolyte imbalance. Objectives. 2/3 (65%) of TBW is intracellular (ICF) 1/3 extracellular water 75 % interstitial fluid (ISF) 25% in blood.
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Fluid and electrolytes in the body Fluid volume changes due to pressure Hormonal regulation of fluid balance Electrolyte imbalance Objectives
2/3 (65%) of TBW is intracellular (ICF) • 1/3 extracellular water • 75 % interstitial fluid (ISF) • 25% in blood Body Fluid Compartments
Fluid and electrolyte homeostasis is maintained in the body Neutral balance: input = output Positive balance(excess): input > output Negative balance(deficit): input < output
Electrolytes – • Cations • Na+, K+ , Ca++, H+ • Anions • Cl-, HCO3- , PO43- Proteins, urea, glucose, O2, CO2 Solutes – dissolved particles
Tonicity Isotonic Hypertonic Hypotonic
Movement of body fluids Diffusion – movement of particles down a concentration gradient.Osmosis – diffusion of water across a selectively permeable membraneActive transport – movement of particles up a concentration gradient ; requires energy
ADH - antidiuretic hormone • thirst Regulation of body water
Decreased amount of water in body • Increased amount of Na+ in the body • Increased blood osmolality • Decreased circulating blood volume Stimulate osmoreceptors in hypothalamus ADH released from posterior pituitaryIncreased thirst
Result: increased water consumption increased water conservation Increased water in body, increased volume and decreased Na+ concentration
Water content of the blood HIGH Water content of the blood LOW Too much water drunk Too much salt or sweating Brain produces More ADH Brain produces Less ADH Water content of the blood normal Low volume of water reabsorbed by kidney High volume of water reabsorbed by kidney Urine output HIGH Urine output LOW (small volume of Concentrated urine) (large volume of dilute urine)
1. Decrease in blood pressure causes decrease in amount of extracellular fluid.
2. Decrease in extracellular pressure near distal convoluted tubule causes juxtaglomerular cells to release the hormone RENIN.
” 3. RENIN in blood stream converts the liver enzyme ANGIOTENSINOGEN into ANGIOTENSIN I.
4. ANGIOTENSIN CONVERTING ENZYME (in the lung) converts Angiotensin I into ANGIOTENSIN II.
5. Angiotensin II causes ADRENAL GLAND to secrete/release ALDOSTERONE.
6. Aldosterone is a vasoconstrictor (increasing blood pressure) and INCREASES COLLECTING DUCT PERMIABILITY.
7.Urine volume decreased • Fluid retained • Blood volume increases • Blood pressure up.