26) Water, Electrolyte, & Acid Base Balance

Question 1

distribution of body fluids

Answer 1

*females are 50% water, males are 60% water
*water content declines to ~45% in old age

Question 2

two different body compartments for fluid

Answer 2

intracellular fluid compartments (ICF)
extracellular fluid compartments (ECF)

Question 3

intracellular fluid compartments

Answer 3

*all the water and electrolytes that are enclosed by cell membrane
*high concentrations of potassium, magnesium, phosphate, sulfa
*major cation- potassium, major anion- hydrogen phosphate

Question 4

extracellular fluid compartments

Answer 4

*fluid found outside the cell, accounts for 1/3 of body fluid
*2 main compartments: plasma 3L, interstitial fluid (IF) 12L
*interstitial fluid consists of lymph, CSF, humors of eyes, synovial fluid, serous fluid, gastrointestinal secretions
*contains high concentrations of sodium, calcium, chloride, bicarb
*major cation- sodium, major anion- chloride

Question 5

movement of fluid in body

Answer 5

*regulated by hydrostatic and osmotic pressures
*water moves freely along osmotic gradients

Question 6

electrolyte output

Answer 6

*lost thru perspiration, feces, and urine
*greatest loss occurs thru urine

Question 7

regulation of electrolyte output

Answer 7

aldosterone- plays biggest role in regulation of sodium by kidneys
*aldosterone levels high- sodium is actively reabsorbed
*aldosterone levels low- sodium is not actively reabsorbed/lost in urine along with increased loss of water

Question 8

renin-angiotensin-aldosterone mechanism

Answer 8

*main trigger for aldosterone release
*juxtaglomerular apparatus secrete renin in response to:
SNS stimulation, <filtrate NaCl level, < stretch of cells due to <BP
*renin catalyzes production of angiotensin II- prompts aldosterone release from adrenal cortex, >sodium reabsorption by kidney tubules

Question 9

atrial natriuretic peptide (ANP)

Answer 9

*release of atrial cells in response to stretch caused by >BP
causes: *<blood pressure & blood volume, *inhibits ADH, renin, & aldosterone production, *increases excretion of sodium & water, *promotes vasodilation

Question 10

calcitonin

Answer 10

*regulate calcium ion concentrations
*parathyroid hormones > calcium and phosphate ion concentration in extracellular fluid by stimulating osteoclast
*also causes kidneys to > calcium reabsorption and > urineary excretion of phosphate ions

Question 11

acid-base balance

Answer 11

*regulation of hydrogen ions in body fluids
*acids are electrolytes that release hydrogen ions
*bases combine with hydrogen ions

Question 12

strength of acids

Answer 12

*vary in the extent to which they ionize
*strong acids ionize more completely
*weak acids ionize less completely

Question 13

strength of bases

Answer 13

*vary in strength
*strong bases combine readily with hydrogen
*weak bases combine with hydrogen ions less readily

Question 14

acid-base buffer system

Answer 14

*composed of sets of two or more chemicals that combine with acids and bases to stabilize the pH
*convert strong acids and bases to weaker
*bicarbonate buffer system, phosphate buffer system, protein buffer system

Question 15

bicarbonate buffer system

Answer 15

*present in both extracellular and intracellular fluids
*in presence of excess hydrogen ions- bicarbonate ions combine with hydrogen ions to form carbonic acid H+ + HCO3- => H2CO3
*if conditions are basic, carbonic acid dissociates te release bicarbonate and hydrogen ions H2CO3 => H+ + HCO3-

Question 16

phosphate buffer system

Answer 16

*present in both extracellular and intracellular fluids
*hydrogen phosphate ions converts a strong acid to a weak acid H+ +HPO4-2 => H2PO4-
*dihydrogen phosphate ion converts a strong base to weak base H2PO4- => H+ + HPO4-2

Question 17

protein buffer system

Answer 17

*intracellular proteins are powerful buffers
*protein molecules can function as both weak acids and bases
*when pH >, carboxyl groups can release hydrogen ion R - COOH => R - COO- + H+
*when pH <, NH2 amino groups bind to hydrogen ion R - NH2 + H+ => R - NH3