Fluids, electrolytes, acids, bases (PathoBk) Flashcards
The sum of all fluids within body compartments.
Total body water, TBW. About 60% of body weight in adults.
One L of water is 2.2lbs.
Comprises about 2/3rds of TBW.
Comprises about 1/3rd of TBW.
Intracellular fluid. Distribution in females is less due to more subcutaneous tissue and smaller muscle mass.
Extracellular fluid. Includes the interstitial fluid, intravascular fluid (blood plasma), and various transcellular fluids (within epithelial-lined body cavities).
Examples of transcellular fluids?
Synovial, cerebro-spinal, GI fluids, pleural, pericardial, peritoneal, urine.
Electrolytes and solutes in intracellular and extracellular fluids? Important for maintaining what between the intra and extra compartments?
Intra: Large amounts of potassium. Small amounts of sodium and chloride. Greater concentration of phosphates and magnesium.
Extra: Large amounts of sodium and chloride. Small amounts of potassium. Greater concentration of calcium.
Electroneutrality, transmission of electrical impulses, and movement of water among compartments.
Fluid movement out of the capillaries and into interstitial space. Movement into the capillary from the interstitial space.
Filtration and reabsorption
As plasma flows from the arterial to the venous end of the capillary, what four forces determine whether the net effect is filtration or absorption?
Called net filtration or starling forces
Capillary hydrostatic pressure (BP): water from capillary into interstitial
Capillary (plasma) oncotic pressure: osmotically attracts water from interstitial into capillary
Interstitial hydrostatic pressure: inward movement of water from interstitial into capillary
Interstitial oncotic pressure: osmotically attracts water from capillary into interstitial
Starling forces are summarized by the equation
Net filtration=forces favoring filtration - forces opposing filtration
Which forces favor and which oppose?
Favoring: capillary hydrostatic and interstitial oncotic
Opposing (favoring reabsorption): capillary oncotic and interstitial hydrostatic
What happens with Starling forces on the arterial vs. venous ends of the capillary?
Arterial end: hydrostatic pressure exceeds capillary oncotic, moving fluid into interstitial space (filtration)
Venous end: oncotic pressure within capillary exceeds capillary hydrostatic pressure, moving fluid into capillary to enter circulation (reabsorption)
Interstitial hydrostatic pressure promotes movement of about 10% of interstitial fluid along with small amounts of protein into the lymphatics. What happens next? Where do the lymphatic and circulatory systems connect?
Once in lymphatic, travels through progressively larger lymphatic vessels until it enters systemic circulation. The two systems connect near the left internal jugular vein where the lymphatic thoracic duct joins the left subclavian vein.
