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Jan 05, 2016
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Fluid and electrolytes in the body Fluid volume changes due to pressure Hormonal regulation of fluid balance Electrolyte imbalance
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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 electrolyte homeostasis is maintained in the body
Neutral balance: input = output Positive balance(excess): input > output Negative balance(deficit): input <
output
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Electrolytes – Cations
Na+, K+ , Ca++, H+
Anions Cl-, HCO3
- , PO43-
Proteins, urea, glucose, O2, CO2
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Tonicity
Isotonic
Hypertonic
Hypotonic
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Cell in a hypertonic solution
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Cell in a hypotonic solution
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Movement of body fluids
Diffusion – movement of particles down a concentration gradient.
Osmosis – diffusion of water across a selectively permeable membrane
Active transport – movement of particles up a concentration gradient ; requires energy
ADH - antidiuretic hormone thirst
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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
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Result:increased water consumptionincreased water conservation
Increased water in body, increased volume and decreased Na+ concentration
Water content of the blood normal
Water content of the blood HIGH
Water content of the blood LOW
Too much water drunk
Too much salt or sweating
Brain producesMore ADH
Urine output LOW
Brain produces Less ADH
Urine output HIGH
High volume of waterreabsorbed by kidney
Low volume of waterreabsorbed by kidney
(small volume of Concentrated urine)
(large volume of dilute urine)
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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.
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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.
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