chapter 24: body fluid homoeostasis Flashcards
2/3 of bodyfluid
intracellular
1/3 of bodyfluid
extracellular
extracellular comprised of (5)
interstitial compartment vascular compartment dense connective tissue bone transcellular fluids
interstitial compartment
between cells
vascular compartment
blood vessels
intracellular fluid rich in
potassium
magnesium
phosphates
proteins
intracellular fluid low in
sodium
chloride
extracellular fluid rich in
sodium
chloride
bicarbonate
extracellular fluid low in
potassium
magnesium
phosphate
fluid homeostasis net result of 4 subprocesses
intake
absorption
distribution
excretion
capillary hydrostatic pressure
outward push of vascular fluid against the capillary walls
osmotic pressure
inward pulling force of particles
ADH released in response to
increases osmolality of extracellular fluid
decrease circulating volume
ADH causes
reabsorption of water in kidneys
decrease fluid excretion
aldosterone released in response to
decreased circulating blood
increased potassium ions in plasma
aldosterone causes
reabsorption of sodium and water
expanding extracellular fluid
ANP
stored in cardiac atrial cells, released when atria are stretched
BNP:
released from ventricular cells when ventricular diastolic pressure is increase (stretch)
ANP and BNP cause
natriuresis, sodium excretion accompanied by water
abnormal fluid loss
GI tubes
emesis
hemorrhage
drainage; fistulas, wounds, open skin, paracentesis
Extracellular ECV imbalance
concentration normal, but too much or too little volume.
body fluid imbalance
concentration of fluid is abnormal
deficit ECV causes
low extracellular volume
emesis, diarrhea, gastric suction, fistula drainage
extensive diuretic use, bed rest
hemmorhage, massive diaphoresis, third spacing, paracentesis, burns
ECV deficit manifestations
wt. loss postural BP decrease tachycardia flat neck veins when supine prolonged capillary refill lightheaded, dizzy syncope oliguria dry mouth hard stools no tears or sweat
ECV excess manifestations
wt gain
edema
circulatory overload: bounding pulse, neck vein distention upright, crackles, dyspnea, orthopnea
ECV excess causes
Excessive IV infusion hyperaldosteronism CHF cirrhosis glomerulonephritis renal disease cushing disease corticosteroid therapy
hyponatremia manifestations
<135 CNS dysfunction malaise anorexia nausea/vomiting headache confusion lethargy seizure coma
hypernatremia manifestations
>145 CNS dysfunction neurons and glial cells shrivel confusion lethargy seizures coma
ECV defici and hypernatremia
clinical dehydration
vomiting and diarrhea
unable to replace water and sodium
s/s: same as hypernatremia and ECV deficit
edema
excess fluid in interstitial compartment (between cells)
causes of edema (4)
increased capillary hydrostatic pressure
increased interstitial fluid osmotic pressure
blockage of lymphatic drainage
decreased capillary osmotic pressure
Increased capillary hydrostatic pressure causes (3)
increased ECV
increased local capillary flow associated with inflammation
venous congestion
increased interstitial fluid osmotic pressure cause
inflammation increases vascular permeability and proteins leak into interstitial fluid.
blockage of lymphatic drainage cause
lymphatic drainage usually removes minute amounts of protein that enter interstitial fluid
- blockage: tumor, parasites, fibrosis, surgical removal of lymphnodes
- accumulation of protein in interstitial fluid
decreased capillary osmotic pressure caused by
decrease concentration of plasma proteins
aldosterone causes excretion of
potassium
diarrhea causes excretion of
potassium and magnesium
hypokalemia manifestations
<3.5 muscle dysfunction (membrane potential) hyperpolarized abd. distention dec. bowel sounds/ paralytic ileus postural hypotension muscle weakness flaccid paralysis respiratory paralysis
hyperkalemia manifestations
>5.0 muscles hypopolarized mild intestinal cramping diarrhea -as worsens skeletal muscles hypopolarized to above resting potential, once discharged will not contract again muscle weakness flaccid paralysis cardiac arrest
plasma calcium 3 forms
bound to protein (albumin)
bound to small organic ions (citrate)
unbound (free)
hypocalcemia manifestations
<4.0 if caused by more binding, total serum normal increased muscle excitability positive: Trousseau and Chvostek signs parasthesias muscle twitching hyper reflexes spasms tetany seizure cardiac dysrhythmia
hypercalcemia manifestations
>5.5 decreased neuro-muscular excitability anorexia nausea/vomiting constipation fatigue polyuria muscle weakness decrease reflexes HA confusion lethargy personality change cardiac dysrhythmia
hypomagnesemia manifestations
<1.5 Mg depresses release of acetylcholine at neuromuscular junctions. inc. mg = dec. acetylcholine increase neuromuscular excitability insomnia increased reflexes muscle cramps grmacing positive: Trousseau and Chvostek nystagmus dysphagia ataxia seizures dysrhythmia
hypermagnesemia manifestations
>2.5 dec. acetylcholine dec. deep tendon reflexes lethargy hypotension flushing diaphoresis drowsiness flaccid paralysis respiratory depression bradycardia dysrhythmia, arrest
hypophostphatemia manifestations
<2.5 important component of ATP anorexia malaise paresthesias hemolysis dec. reflexes muscle aches/ weakness respiratory failure impaired cardiac function
hyperphosphatemia manifestations
>4.5 (hypocalcemia) increased neuormuscular excitability positive: Trousseau, Chvostek paresthesias muscle twitches/ cramps increased reflexes spasms seizures cardiac dysrhythmia
increased capillary permeability -> edema
burn, allergic inflammation reaction = inc. capillary permeability
- > proteins can move through membrane/ loss of plasma proteins
- > increased tissue oncotic pressue
- > edema
decreased production of plasma proteins -> edema
cirrhosis, malnutrition = dec. production of plasma proteins
- > decrease in capillary oncotic pressure due to less proteins
- > fluid build up in tissues
- > edema
increased capillary hydrostatic pressure -> edema
venous obstruction, Na & H2O retention, HF = inc. capillary hydrostatic pressure
- > fluid moves into tissue due to hydrostatic pressure of capillaries > hydrostatic pressure of ECF
- > edema
