Fluid and electrolytes Flashcards
Intracellular fluid (ICF)
inside the cells
Where is 2/3 of the body’s water located
Intracellular fluid
Extracellular fluid (ECF)
outside the cells, within the bloodstream
Interstitial fluid (ISF)
between the intracellular and extracellular spaces
Where is there a constant fluid exchange between
ICF and ECF
Hydrostatic pressure
the pressure is exerted by water
Where does hydrostatic pressure move fluid
pushes water from the bloodstream into the ISF and ICF
Osmotic pressure
the pressure exerted by solutes
Where does osmotic pressure move fluid
pulls water into the bloodstream from the ISF and ICF
What leads to higher osmotic pressure
higher concentration
Oncotic pressure
pressure exerted by albumin
Where does oncotic pressure move fluid
pulls water into the bloodstream from ISF and ICF
Starlings law
hydrostatic pressure and osmotic pressure opposed each other, controlling movement between different fluid compartments to maintain fluid balance and homeostasis
If osmotic pressure is higher than hydrostatic pressure, where does fluid move
out of cells into ECF
If hydrostatic pressure is higher than osmotic pressure, where does fluid move
into cells out of the ECF
Osmolality
osmoles of solute per kg of solvent - mass of solvent
Osmolarity
osmoles of solute per liter of solution - volume of total solution
Tonicity
the amount of solutes in a solution compared to the bloodstream
Isotonic solution
equal concentration as the blood
When do you use isotonic solution
as a bloodstream volume expander
Example of isotonic solution
0.9% NaCl
Hypotonic solution
lower concentration than the blood
What does a hypotonic solution do
Shift fluid from ECF to ICF to increase hydrostatic pressure
What solution is used to treat dehydration
hypotonic
Example of hypotonic solution
0.45% NaCl, half normal saline
Hypertonic solution
higher concentration than the blood
What does a hypertonic solution do
causes a fluid shift from ICF to ECF, increases osmotic pressure
What solution is used to diminish cell swelling, treat cerebral edema
hypertonic
Example of hypertonic solution
mannitol, 3% NaCl
What part of the brain responds to changes in blood osmolarities and blood fluid volume
osmoreceptors in the hypothalamus
What happens when blood osmolarity is high (concentrated)
the thirst center is stimulated to get more fluid into the body, ADH is released to prevent fluid from leaving the body
When is renin released
in response to decreased renal perfusion
Renin-angiotensin-aldosterone system (RAAS)
renin converts angiotensin into angiotensin 1 –> angiotensin 1 is converted into angiotensin 2 through the angiotensin-converting enzyme (ACE) in the lungs –> angiotensin 2 stimulates the release of aldosterone to increase sodium and water reabsorption into the bloodstream to increase blood volume
When are natriuretic peptides secreted
in response to fluid volume overload
What do natriuretic peptides do
promote glomerular filtration rate and the excretion of water and sodium to decrease fluid volume
What are the main causes of edema
elevated hydrostatic pressure, diminished osmotic pressure, inflammation
How does elevated hydrostatic pressure cause edema
excess water in the bloodstream pushes water out of the bloodstream into the ISF and ICF spaces
How does diminished osmotic pressure cause edema
a low amount of solutes in the bloodstream decrease the pulling of fluid back into the bloodstream
How does inflammation cause edema
increased capillary permeability
Dependent edema
forms in the lower extremities due to a weakened venous valve system, lack of muscle contractions, and gravitational forces
Pitting edema
visible indentations when pressure is applied and fluid is displaced
Third spacing
when fluids become hidden in body cavities that are normally free of fluid
What is the role of sodium
conducts nerve impulses, contract and relax muscle and maintain the proper balance of water and minerals
Treatment of hypernatremia
drinking more water, infusion of hypotonic fluids, diuretics
Clinical manifestations of hypernatremia
muscle weakness, restlessness, extreme thirst, confusion, lethargy
Causes of hypernatremia
water depletion
Hypovolemia hyponatremia
loss of both fluid and sodium
Clinical manifestations of hypovolemia hyponatremia
thirst, dry mouth, hypotension, tachycardia
Causes of hypovolemia hyponatremia
adrenal insufficiency, diuretic use, diarrhea, vomiting, excess sweating
Hypervolemic hyponatremia
loss of sodium but a large amount of fluid
Clinical manifestations of hypervolemic hyponatremia
headache, lethargy, confusion, nausea, vomiting, diarrhea, muscle cramps/spasms, coma, neurological damage due to swelling
Hypervolemic hyponatremia causes
impaired water excretion
What is the role of potassium
helps nerves, muscles, and heart function, move nutrients and waste, maintain normal fluid levels inside our cells
Hyperkalemia clinical manifestations
weakness, fatigue, heart palpitations, shortness of breath, chest pain, high potassium blood levels
Hyperkalemia treatment
calcium, insulin, glucose, sodium bicarbonate, dialysis, increased renal excretion
Hypokalemia causes
excessive elimination through urine due to medications, vomiting, diarrhea, excessive sweating, cushings syndrome
Hypokalemia clinical manifestations
muscle twitching, cramps, weakness, hypotension, lightheadedness, excessive urination, excessive thirst
Hypokalemia treatments
potassium supplements, potassium-rich foods
Acid
a compound that donates hydrogen ions in a solution
Base
a compound that accepts hydrogen ions in a solution
Buffers
a neutralizer that attempts to balance the pH
What organ regulates carbon dioxide
lungs
What happens in respiratory acidosis
increase ventilation –> eliminate CO2 –> raise the pH
What happens in respiratory alkalosis
decrease ventilation –> retain CO2 –> lower the pH
What organ regulates bicarbonate
kidneys
Metabolic acidosis
increase reabsorption in the bloodstream –> raise pH
Metabolic alkalosis
increase secretion in the urine –> lower pH
