fluid-electrolyte and acid-base imbalances Flashcards
FLUID=
water and electrolytes
anions=
-
bicarbonate (HC03)- neutralize stomach acid, maintain acid-base balance
chloride (Cl)- component of stomach acid, maintain acid-base balance, maintain water balance
phosphate (PO4)- maintain acid-base balance, protein and energy metabolism, structure of cell membranes
cations=
\+ calcium magnesium potassium sodium hydrogen
what is CHP
capillary hydrostatic pressure
the PUSH pressure
-pressure fluid EXERTS on vessel walls OUT of capillaries
what is OP
osmotic pressure
-change in plasma protein concentration (amt of plasma protein or changes in H20 volume)
PULL pressure
-pressure coming from solutes drawing fluid IN to capillaries
NFP=
net filtration pressure (CHP-BCOP)
there is a net…
LOSS of fluid from capillaries into interstitial space
movement of fluid is _____
OUT OF capillaries
what returns the fluid from the interstitial tissues to blood?
LYMPHATIC system
what is edema?
extra fluid (excessive/abnormal) accumulation in interstitial space
where can edema be LIFE threatening?
BRAIN!, lungs! heart!
causes of edema? (4)
- increased capillary hydrostatic pressure
- decreased colloid osmotic osmotic pressure
- increased capillary permeability
- obstructed lymph flow
how does increased capillary hydrostatic pressure cause edema?
- INCREASED vascular volume (HF, kidney disease, premenstrual sodium retention, pregnancy, envrionmental stress, thiazolidinedione therapy)
- venous obstruction
- decreased arteriolar resistance (calcium blocking drug response)
how does decreased colloid osmotic pressure occur?
- increased loss of plasma proteins
- decreased production of plasma proteins
increased capillary permeability as a cause of edema?
-inflammation, allergic rection, malignancy, issue injurys and burns cause INCREASED permeability
obstructed lymph flow occurs from?
malignant obstruction, surgical removal of lymph nodes
what is dehydration?
decreased interstitial and intravascular fluids
-KIDNEY not fx properly or losing fluid (draws from IS and cells)= DEHYDRATED cells
causes of dehydration?
-decreased intake of fluid, third spacing, perspiration, vomiting/diarrhea, flirtration in kidneys
what is third spacing?
two NORMAL spaces for fluid= intravascular space and interstitial space
—-> continually exchange fluid
3rd space= ABNORMAL, transcellular space
example. ascites in abdomen, bleeding into a cavity or joint, pleural space
difficult to happen and just as difficult to get OUT
measure of pH is measure of
hydrogen ions
normal pH of extracellular fluid
7.35-7.45
pH is constantly changing because of?
reactions in body, generating H+
MANY compensatory mechanisms
ABGs?
arterial blood gases= test blood from an artery for:
- certain gases amt (CO2 and O2) dissolved in blod.
- measures PH
what is alkalosis?
increased BASE pH greater than 7.45
-LOW hydrogen
what is acidosis?
increased ACID pH less than 7.35
-HIGH hydrogen
4 types of metabolic imbalances?
- metabolic alkalosis
- respiratory alkalosis
- respiratory acidosis
- metabolic acidosis
pH is dependent on?
BALANCE between bicarbonate and carbonic acid
what is the homeostatic balance of bicarbonate ion and carbonic acid?
20:1 ratio 20 bases, 1 acid
NORMAL pH is maintained by what 3 systems?
BUFFERing system
LUNGS
KIDNEYS
how does the buffer system work?
- carbonic acid-bicarbonate buffer is used in the blood
- chemicals in ICF and ECF providing IMMEDIATE response
- weak base + conjugate acid pair, or weak acid + conjugate base pair (to prevent large changes in pH, system TRADES strong acid for weak acid or strong base for weak base)
- pick up extra H+ if levels are HIGH
- release H+ if levels are LOW
- buffers cannot get RID of H+, so if buffering capacity exceeded, OTHER mechanisms needed!
how do the lungs work to maintain pH?
- CO2 exhaled by lungs
- if lungs FAIL= BUILD up of C02, acidosis
- CHEMORECEPTORS in brainstem and peripheral chemoreceptors sense change in pCO2 and ALTER ventilation rate to MAINTAIN acid-base balance
- RAPID response (minutes)
- only 50-75% as effective as buffer system
- PREVENTS large pH changes while waiting for slower acting kidneys to respond
how do the kidneys work to maintain pH?
- SLOWEST response (hours to days)
- EXCRETE more or less H+—> H+ from fixed acids resulting from protein and lipid metabolism
- REABSORB more or less HCO3, filtered in glomerulus so that it is not lost in urine
- generates new HCO3 and releases in blood
equation
CO2 + H20 H2CO3 H+ + HCO3-
the direction of the reaction is determined by?
concentration of reactants and products
moves TOWARD side with LOWER concentration (LE CHATELIERS principle)
carbonic acid is volatile… which means
as soon as it forms it dissociates (so HARD to measure conc in blood)
only volatile acid in body
how is ABG measured?
small volume of blood drawn from artery (most commonly radial artery on wrist)
- interpreted to determine acid-base imbalances
- can also measure lactate, hemoglobin, electrolytes and others
metabolic imbalances occur when
any fixed acids involved lactic acid, HCl
respiratory imbalances occur when
carbonic acid is involved
metabolic acidosis=
too much acid or too little base causes= severe diarrhea (lose HCO3), diabetes (ketones broken into acid, strenous exercise (lactic acid) or renal failure response: buffers PICK up extra H resp increases (H20 and CO2 exhaled) kidneys (secrete more H, reabsorption)
metabolic alkalosis=
too much base or too little acid
causes= vomiting (lose H from stomach), excess intake of antacids (increase HCO3)
response: buffers drop off H
ventilation decreases (less Co2 lost)
kidneys secrete less H, reabsorb less HCO3
what is respiratory acidosis=
lungs FAILING, not adequately ventilating! CO2 not exhaled and builds up
causes: lung disease, depression of resp centers due to drug, nerve/muscle disorders decrease resp, holding breath
results in increased PCO2, excess CO2 combined with water to form carbonic acid
response: buffers pick up excess H+
kidneys excrete H, reabsorb HCO3
what is respiratory alkalosis=
hyperventilation, CO2 exhaled EXCESSIVELY, reactant conc drops so more H2CO3 converted into CO2
causes: fever, anxiety, aspirin positioning, high altitude
response: buffers drop off H
kidneys excrete less H, reabsorb more HCO3
compensation is what?
LUNGS and KIDNEYS will compensate for each others FAILURE! to maintain pH
- LUNGS failing not exhaling CO2, rxn moves right and kidneys excrete excess H+
- KIDNEYS failing and retaining H not excreting, rxn moves left so carbonic acid formed and dissociated into CO2 to be exhaled by lungs
treatment for acid-base imbalances?
administer solutions (oral or IV) to normalize pH -must address underlying problem though!
