Chapter 26 Flashcards
Extracellular Fluid
20% of body weight
Major cation is Na+ (sodium)
Major anion is Cl- (chloride)
Except higher protein, lower Cl- content in plasma
Intercellular Fluid
40% of body weight
Low Na+ and Cl-
Major cation is K
Major anion is HP04, more soluble protein than plasma
What happens with an overall rise in osmolarity
Stimulates thirst, ADH release, reabsorption via aquaporins.
What is hypotonic hydration
Too much water, no electrolytes, hyponatremia - net osmosis into tissue cells, swelling of cells leads to death.
Treated with hypertonic saline
How is sodium regulated
65% Na+ reabsorbed in proximal tubules, 25% reclaimed in loops, Na+ never secreted into filtrate
water in filtrate follows Na+ if ADH is present, increased Na+ in urine and increased water loss.
How is potassium regulated
K+ part of body buffer system
H+ shifts in and out of cells in opposite direction maintain cation balance.
ECF K+levels rise with acidosis, ECF K+ levels fall with Alkalosis.
Bicarbonate buffer system
Acid - HCO3 - ties up H+ and forms H2C03
HCO5- is alkaline reserve and regulated by kidneys
Base - H2C03 donates H+
H+ ties up base
H2CO3 supplied by respiration
Phosphate buffer system
Effective buffer in Urine and ICF, where phosphate concentrations are high
H2PO4- - weak acid
HPO42- - weak base
Protein buffer system
Intracellular proteins are most plentiful and powerful buffers and amphoteric
3 Chemical buffer systems
Bicarbonate buffer system
Phosphate buffer system
Protein buffer system
2 General physiological regulators of acids and bases
Lungs - eliminate volatile carbonic acid by eliminating CO2 higher respiratory rate.
Kidneys - eliminate non volatile acids from cellular metabolism and regulate.
