Chapter 21 - Chapter 21 1 Distinguish between intracellular and extracellular fluid A Intracellular fluid fluid in cells 1 63 of total body fluid

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Chapter 21 1. Distinguish between intracellular and extracellular fluid. A. Intracellular fluid – fluid in cells 1) 63% of total body fluid is confined to the intracellular fluid compartment in the body of an average adult male B. Extracellular fluid – fluid outside cells 1) 37% of the total body fluid is confined to the extracellular fluid compartment in the body of an average adult male 2) Contains the following fluids: a. Interstitial fluid b. Plasma c. Lymph d. Transcellular fluid 2. Identify the fluids that collectively comprise “transcellular” fluid. A. Transcellular fluid – part of the extracellular fluid, including the fluid in special body cavities 1) Includes: a. Cerebrospinal fluid b. GI tract fluids c. Synovial fluid d. Aqueous humor e. Vitreous humor f. Serous fluids 3. Explain the factors involved in regulating the movement of water and electrolytes from one compartment to the other. A. Hydrostatic pressure – pressure exerted by a fluid B. Osmotic pressure – pressure resulting from differing concentrations of impermeable solutes in a water solution on either side of the membrane 1) Na + concentration in the interstitial fluid is normally high. a. Decrease in the concentration of extracellular Na + will cause a net movement of water from the extracellular compartment into the intracellular compartment. b. Consequence of this movement, cells will swell 2) Concentration of Na + increase, net movement of water will be outward from the intracellular compartment a. Cells shrink because of dehydration 4. Explain the regulation of water intake. A. The body loses as little as 1% of its water. B. An increase in the osmotic pressure of extracellular fluid due to water loss stimulates osmoreceptors in the thirst center. C. Activity in the hypothalamus causes the person to feel thirsty and to seek water. D. Drinking and the resulting distension of the stomach by water stimulate nerve impulses that inhibit the thirst center. E. Water is absorbed through the walls of the stomach and small intestine. F. The osmotic pressure of extracellular fluid returns to normal. 5. Discuss the events that lead up to dehydration and water intoxication. A. Dehydration 1) Extracellular fluid becomes osmotically more concentrated 2) Osmoreceptors in the hypothalamus are stimulated by the increase in the osmotic pressure of body fluids. 3) The hypothalamus signals the posterior pituitary gland to release ADH into the blood. 4) Blood carries ADH to the kidneys.
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Chapter 21 5) ADH causes the distal convoluted tubules and collecting ducts to increase water reabsorption. 6) Urine output decreases, and further water loss is minimized. B. Excess Water Intake
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This note was uploaded on 01/14/2011 for the course BIO 142 taught by Professor Unknown during the Spring '10 term at Northern Virginia Community College.

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Chapter 21 - Chapter 21 1 Distinguish between intracellular and extracellular fluid A Intracellular fluid fluid in cells 1 63 of total body fluid

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