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
Alkalosis:
pH body fluids above 7.45
Which body fluid compartments contains the highest concentration of proteins?
intracellular
The capillary endothelium separates these two body fluid compartments
plasma and interstitial fluid
Which mechanism is the main regulator of water intake?
thirst
Which factor stimulates ADH secretion?
high ECF osmolarity
Which factor would cause a shift of water from the plasma to the interstitial fluid?
increased blood (hydrostatic) pressure
An increase in the ECF Na+ levels would cause
water to shift out of the ICF and into the ECF
The major cation in the extracellular fluid is
Na+
ECF calcium levels are mainly regulated by which of the following hormones?
parathyroid hormone
Which hormone stimulates the kidneys to excrete excess potassium?
aldosterone
Strong acids can be buffered by
weak bases
Respiratory acidosis may be caused by
hypoventilation
Prolonged hyperventilation could cause
respiratory alkalosis
A person who has unregulated diabetes mellitus may also have
metabolic acidosis and dehydration
Prolonged diarrhea can cause
metabolic acidosis and dehydration
Buffer systems do which of the following?
minimize pH changes in body fluids by converting stronger acids or bases into weaker acids or bases
Respiratory alkalosis would be indicated if blood pH is _____ and blood carbon dioxide levels are ______.
high; low
Parathyroid hormone __________ blood calcium levels and calcitonin __________ blood calcium levels.
increases, decreases
__________ is necessary for the transport of Ca2+ ions across the wall of the intestinal tract.
Vitamin D
The ____________ are the primary organs that regulate the composition and volume of body fluids.
kidneys
The largest buffer system in the body is the
protein buffer system
If the pH of the blood decreases, the pH of the urine will
decrease
As the rate of sweat production increases, the amount of sodium lost in the urine
decreases
Respiratory alkalosis is caused by ____________ and can be compensated for by the production of a more ____________ urine.
hyperventilation, alkaline
