Fluid Systems Flashcards
About how much of the body weight in the average adult is water?
60% (overall avg. is 45-60%)
Why do we lose water body weight percentage as we age?
As we age, we tend to lose muscle and gain fat
Where is most of the body’s fluid located?
Intracellular fluid (70%) [extracellular intravascular (plasma) = 6%, extracellular extravascular (interstitial fluid) = 26%]
True or False:
ECF is quite similar to ICF
False; plasma and interstitial fluid are similar because they are both outside the cell - ICF in inside the cell, which is vastly different from outside the cell, which has much more negatively charged electrolytes
Movement of water through a semipermeable membrane toward an area of greater solute concentration is due to ___________.
Osmotic pressure
What accounts for the osmotic pressure in tissues and cells?
Osmotic pressure
Number of molecules of a substance in a kg of water
Osmolarity
What is the osmolarity of normal serum?
285-295 mOsm/kg
Water moves from an area of high pressure to an area of low pressure.
Hydrostatic pressure
Is BP higher or lower in an arteriole than tissue pressure? A venule?
Higher; lower
Affects osmotic pressure and can regulate how much fluid moves into the tissue and move it back into the capillary bed and out the venules
Capillary fluid dynamics
ECF is filtered through the renal _____.
Glomeruli
Selective reabsorption and excretion of water and solutes occur in renal _____.
Tubules
The mechanism that brings glucose and other nutrients back into the body after they are filtered out
Selective reabsorption
Severe hydration; decreases renal perfusion; causes release of aldosterone from the renal cortex
Hypovolemic state
What hormone directly conserves water and is released by the pituitary gland?
Antidiuretic hormone (ADH) aka Vasopressin
What hormone indirectly conserves water and is released by the adrenal cortex?
Aldosterone
Name the 3 steroidal hormone types that bind to intracellular receptors, all work to conserve water and all come from the adrenal gland?
- Gonadal
- Glucocorticoids
- Mineralocorticoids
Formed in the hypothalamus; stored in the post. pituitary; area of storage and relate may overlap with the thirst center
ADH
What are the major stimuli for release of ADH?
- Increased osmolarity
- Decreased volume of ECF
- Stress of trauma, surgery, pain, and some anesthetics and drugs
A significant decrease in ADH from lesions or trauma of the hydrophyseal tract causes __________.
Diabetes insipidus (massive increase in urine output)
Secreted by the adrenal gland; acts on renal tubules to increase Na+ uptake
Aldosterone
What are the stimuli for the release of aldosterone?
- K+ concentration
- Na+ concentration
- Renin-angiotensin system
Naturally occurring fatty acids, fxns in the inflammatory response, BP control, uterine contractions, and GI mobility; causes vasodilation in kidneys, promoting Na+ excretion
Prostaglandins
Secreted by the adrenal cortex; weak activity for reabsorption of Na+ and water; increases blood volume and Na+ retention
Glucocorticoids
Causes increased kidney excretion of water and Na+; improved glomerular filtration rate; inhibits renin secretion; inhibits release of ADH
ANP