Chapter 27_AP2 Flashcards
Water, Electrolytes, and Acid-Base Balance
Intracellular fluid compartment
–
All fluids inside cells of body
–
About 40% of total body weight
Extracellular fluid compartment
– All fluids outside cells – About 20% of total body weight – Subcompartments • Interstitial fluid and plasma; lymph, CSF, synovial fluid
Primary intracellular ions, interstitial fluid ions, and plasma ions
– Intracellular cation = K+ – Interstitial fluid cation = Na+ – Plasma cation = Na+ – Intracellular anion = Phosphate – Interstitial fluid = Cl- – Plasma anion = Cl-
Kidneys
primary regulators of water excretion
Regulation processes
– Osmosis – Osmolality – Baroreceptors – Learned behavior
Sources of water
–
Ingestion
–
Cellular metabolism
Routes of water loss
–Urine –Evaporation •Perspiration •Respiratory passages –Feces
Osmolality
Measure of water vs. solute concentration; the higher the solute concentration, the higher the osmolality
Increased osmolality
triggers thirst and ADH secretion
Decreased osmolality
inhibits thirst and ADH secretion
ECF
can increase or decrease even if osmolality of extracellular fluid is maintained
Insensible perspiration
is water evaporating from skin.
Sensible perspiration
is secreted by the sweat glands. Contains solutes
Hypernatremia:
elevated plasma Na+
Hyponatremia:
decreased Na+
Acids
Release H+ into solution
Bases
Remove H+ from solution
Buffers:
Resist changes in pH
Types of buffer systems
–Carbonic acid/bicarbonate
–Protein
–Phosphate
if pH rises
buffers release H+
if pH falls
buffers bind H+
Respiratory center:
if pH rises, respiratory rate decreases; if pH falls, respiratory rate increases
Kidneys:
if pH rises, distal tubule decreases H+ secretion into the urine and decreases HCO3- absorption into the blood (more H2CO3 will dissociate into H+ and HCO3-); if pH falls, distal tubule increases H+ secretion into the urine and increases HCO3- absorption into the blood
Acidosis:
pH body fluids below 7.35
