patho Flashcards
sodium-potassium pump
sodium: •main determinant of osmolarity
•positive ion, also called a cation
found mostly in the ecf and assists in the maintenance of fluid balance and osmotic pressure
potassium: •main ICF cation
•assists in maintenance of neuromuscular excitability and acid-base balance.
•Both sodium and potassium require the cell’s sodium/potassium ATPase pump to maintain Na+ as the extracellular ion and K+ as the intracellular ion.
hydrostatic pressure
Pushing force exerted by water in the bloodstream
•The heart’s pumping action is the source of hydrostatic pressure.
•Exerts an outward force that pushes water through the capillary membrane pores into the ISF and ICF compartments
•ECF water à ICF compartment
-high pressure from the heart into your arteries
brain natriuretic peptide (BNP)
if our ventricle is expanded because of that excess volume, then BNP is released, if the brain senses too much volume it causes BNP to release
-too much volume in the brain causes cellular swelling, and when we have edema in the brain, it causes us to lose consciousness, and if it goes too far, we will die
hyPOvolemic hyponatremia
-both sodium and water lost as the SAME time (sodium more)
-•Renal causes:
•Adrenal insufficiency, osmotic diuresis, diuretic use
•Nonrenal (primarily GI losses):
•Excessive sweating, diarrhea, vomiting
•Thirst, hypotension, and tachycardia are present
•Neurological deficits may develop
•Treatment
•Slow replacement of sodium with adequate fluid
hyPERvolemic hyponatremia
Excess water, sodium is diluted
•Example: syndrome of inappropriate ADH (SIADH)
•Headache, lethargy, confusion, muscle cramps
•If serum osmolality falls, water moves from ECF into ICF, causing cell swelling (may affect brain cells, leading to seizure and coma)
•Treatment involves correcting etiology of excess fluid
hypernatremia
-sodium level greater than 145
-losing water BIG TIME
•Sodium level >145 mg/dL
•Can occur with excess of decrease in body water
•Most common cause: water loss
•Cells become dehydration and shrink
•Elderly and infants at highest risk
•Clinical manifestations can be divided into two distinct patterns, one with fluid overload and one without fluid overload
•Neuron shrinkage
•Electrolyte imbalances across membrane
•Changes in membrane potentials and cell responsiveness to signals
hypernatremia with water retention (hypervolemic hypernatremic)
If hypernatremia causes water retention, then look for edema
•Weight gain is often present.
•Hypertension also occurs.
•If severe, mental changes and pulmonary edema occur.
•If no fluid overload
•Dehydration, thirst, tachycardia, and oliguria
•Treatment- fix underlying cause
hypokalemia
•Blood K+ concentration less than 3.5 mEq/L
•Diuretic therapy most common cause
•Most K+ loss from body through renal system
•Renal losses increase with stress, metabolic alkalosis
•Burns, vomiting, diarrhea
•Other causes: large amounts of IV dextrose, administration of adrenergic agents, dietary deficiency, ng suction, hyperaldosteronism, salt wasting kidney disease, gi surgery, alkalosis & laxative abuse
•NPO patients require 10 to 30 mEq/day K+ supplementation.
symptoms of hypokalemia
Anorexia
•Nausea
•Vomiting
•Sluggish bowel
•Cardiac arrhythmias- prolonged PR interval, flattened t wave, prominent u wave
•Postural hypotension
•Muscle fatigue
•Weakness
•Leg cramps
•Decreased DTRs
hyperkalemia
•Potassium level >5.2 meq/l
•Causes:
•Excessive intake of K, Aldosterone deficiency, Na depletion, Acidosis, Tissue trauma, burns, Extreme exercise, renal failure, Addison’s disease (lack of cortisol), hemolysis, potassium-sparing diuretics, Ace inhibitors
•If levels severe (>7.0 mEq/L) rapid treatment to move K+ from ECF to ICF needed
•Infusion of 50% dextrose, insulin, sodium bicarbonate
•Diuretic may also be given
symptoms of hyperkalemia
Nausea, vomiting, diarrhea
•Intestinal cramping
•Numbness, tingling of extremities
•Muscle weakness
•Muscle cramping
•Dizziness
•Apathy, mental confusion
•Diagnosed through BMP level
•ECG changes- tall, peaked t wave, wide qrs complexes
•Risk of cardiac arrest with severe K excess**
calcium
the major mineral contents of bone & teeth; also involved with blood clotting & neuromuscular signaling
•Vitamin D facilitates the absorption of calcium from the gastrointestinal tract into the bloodstream.
•Parathyroid hormone (PTH) regulates Ca & po4
•When the plasma calcium level is low, PTH is stimulated; when the plasma calcium level is high, PTH is inhibited.
•Calcitonin, a hormone produced by the thyroid, acts at the bone and kidneys to remove calcium from the circulation.
•Calcium found in free or bound forms (bound to albumin)
hydrostatic pressure
in charge of filtration of fluid out of arteriolar end of capillary into the interstitial spaces of tissues
osmotic pressure
Higher at venular end of capillary forces fluid back into capillary space
Oncotic pressure (colloidal pressure) is force exerted specifically by albumin in the bloodstream
edema
Edema occurs when there is an excess of fluid in the ISF and ICF compartments.
Causes
elevated hydrostatic pressure created by excess water in the bloodstream
diminished osmotic force created by a low amount of solutes in the bloodstream.
Hypoalbuminemia – liver failure, protein malnutrition
Dependent edema
Sodium retention
sequestered fluids
Fluid accumulates in body cavities normally free of fluids
AKA: third-space accumulation or third-spacing
Pericardial sac, peritoneal cavity, and pleural space
Fluid called “effusion”
Transudate: Serous filtrate of blood (yellow type of thicky fluid like a blister)
Exudate: Contains blood, lymph, proteins, pathogens, inflammatory cells (more like pus, more infectious)
first space is in your vessels, second space is in your cells, and third space is the interstitial space between vessels and cells
hypervolemic (fluid volume overload)
too much fluid, usually means heart failure
clinical manifestations of hypervolemia
Rapid weight gain (2lbs = 1 l of fluid)
Noticeable swelling in arms, legs, face
Swelling in abdomen
Cramping, headache, stomach bloating
Shortness of breath; crackles in lungs
High blood pressure, bounding pulse
Heart problems including congestive heart failure
dehydration
State of diminished water volume in body (hypovolemia)
Fluid moves from ICF causing cells to shrink (cellular dehydration)
Response to dehydration
Osmoreceptors stimulate thirst, ADH release
Vasoconstriction and increased HR
RAAS activated
Decreased circulating blood volume leads to tachycardia and hypotension
Causes
Reduced fluid intake
Reduced ADH or kidneys not responsive to ADH
Burns, fever, perspiration
Osmotic diuresis, as occurs with elevated blood glucose levels
Hypernatremia
hypovolemia symptoms
Thirst
Dry mucous membranes, sunken eyes
Poor skin turgor
Hypotension- orthostatic hypotension
Low urine output
Dark-colored urine
Weight loss
tachycardia
In newborn; depressed fontanelle
Diagnostic testing
High blood urea nitrogen (6-24 mg/dl)
Oliguria
Hypernatremia caused by low water in the blood
dehydration —> stimulation of osmoreceptors in blood vessles
stimulation of thirst center in hypothalamus in brain
dehydration —> stimulation of peripheral baroreceptors in blood vessels
sympathetic nervous system —> increased HR and vasoconstriction of blood vessels
dehydration —-> stimulation of kidney to secrete renin
RAAS —> raises blood volume and blood pressure
dehydration —> stimulation of osmoreceptors
stimulation of posterior pituitary gland of brain —> ADH —> water reabsorption at nephron of kidney
