Fluid and Electrolytes Exam 3 Flashcards
Total body water
60% of weight of 70kg adult male around 42L
2/3 intracellular
1/3 extracellular
total body water content ______ with age, so babies and children…
declines with age, so babies and children have more % than adults
Older adult changes that make them prone to dehydration?
lower % total body water
increase in adipose and decrease muscle
renal decline
diminished thirst perception
*all of these make the elderly prone to dehydration
osmosis
movement of water down concentration gradient…area of lower solute concentration to higher solute concentration
osmotic forces
amount of hydrostatic pressure required to overcome osmotic movement of water
movement of fluid from the capillary into the interstitial space
filtration
movement of fluid from the interstitial space into the capillary
reabsorption
Forces favoring filtration (movement into interstitial space from capillary) or forces apposing reabsorption
capillary hydrostatic pressure (blood pressure)
interstitial oncotic pressure (water pulling)
Forces opposing filtration or forces favoring reabsorption (movement into the capillary)
plasma (capillary) oncotic pressure (water pulling)
interstitial hydrostatic pressure
major forces for filtration and reabsorption are those ______ the capillary = ?
within…= capillary hydrostatic pressure (filtration) and capillary oncotic pressure (reabsorption)
Accumulation of fluid in the interstitial spaces. Causes?
Edema
see slide 12 for causes
Lymph obstruction causes
decreased transport of capillary filtered protein, which causes an increase in tissue oncotic pressure
remember that increased capillary permeability can cause edema how? And what causes this?
loss of plasma protein to interstitial space and therefore decreases capillary oncotic pressure
*causes of this are burns and inflammation (injury)
Edema can be _____ or ______
localized or generalized
local - limited to site of trauma or specific organ system (sprained ankle, cerebral edema, pulmonary edema, pleural effusion, pericardial effusion, and ascites)
generalized - dependent edema, third spacing
Third space =
interstitial space, pleural space, pericardial space. Therefore, not available for metabolic processes or perfusion.
major intracellular electrolytes
Cation - potassium (K+)
anions - phosphate and organic ions
major extracellular electrolytes
Cation - Na+
anions - Cl-, bicarb HCO3-
sodium regulates osmotic forces, thus
water
Sodium roles?
neuromuscular irritability, acid-base balance, cellular reactions, and transport of substances
what is sodium regulated by?
aldosterone and natriuretic peptides
normal amount of sodium in the blood?
135-145 mEq/L
primary anion in ECF
chloride - and it provides electroneutrality
chloride does what with sodium? and what with bicarb?
CHLORIDE FOLLOWS SODIUM, AND VARIES INVERSELY WITH BICARBONATE
A mineralocorticoid steroid synthesized and secreted by the adrenal cortex
aldosterone
when is aldosterone secreted?
SECRETED WHEN SODIUM LEVELS ARE DEPRESSED, POTASSIUM LEVELS INCREASE, OR RENAL PERFUSION IS DECREASED
aldosterone secretion leads to?
SODIUM AND WATER REABSORPTION BACK INTO THE CIRCULATION AND POTASSIUM AND HYDROGEN SECRETION TO BE LOST IN URINE
when is RENIN released? where is renin released from?
SNS activation or decreased perfusion/blood pressure int he renal vasculature…this leads to release of renin from juxtaglomerular cells of the kidney