Kaplan Physio Flashcards
Extracellular Volume: When there is a net gain of fluid by the body, this compartment always _____
enlarges
ICF = what % of TBW
2/3
Concentration of solutes is the equivalent to
body osmolality
At steady-state, the intracellular concentration of water equals the _________concentration of water (remember the cell membrane is not a barrier for water).
extracellular
ECF = what % of TBW
1/3
what controls volume regulation?
Aldosterone and ADH
Intracellular fluid volume is determined by Extracellular fluid osmolality. We change the _______ first then this changes the _______
We change the extracellular volume first then this changes the intracellular volume
ECF is made up of
- 3/4 = interstitial fluid (ISF)
- 1/4 = plasma volume (PV)
Intracellular volume is only altered if ________
extracellular osmolality changes
if ECF osmolality increases, cells ______ water and _____
if ECF osmolality increases, cells lose water and shrink
the greater the [solute] the ___ the [water] will be
the greater the [solute] the LOWER the [water] will be
- If the overall osmolarity doesn’t change then you had an _____ fluid loss
- ex)
- causes
- If the overall osmolarity doesn’t change then you had an ISOTONIC fluid loss
- ex) hemorrhage, diarrhea, vomiting
- causes decrease in BP, increase in RAAS and increase in ADH
A net loss of body fluid ______ extracellular volume
decreases
- ex) of a hypotonic fluid loss
- a consequence of a hypotonic fluid loss
- ex) sweating/respiration
- ex) hypotonic urine in DI (decrease in ADH could be cause)
- decrease BP
- increase RAAS and ADH
the intracellular and ____________ osmolalities are the same at steady-state
extracellular
effect of giving a hypertonic saline
- increase BP
- decrease RAAS, ADH
Loss of isotonic fluid, what happens to:
- ECF Vol
- ICF Vol
- Body osmolarity
- ex)
- decrease ECF
- no change ICF
- no change osmolarity
- hemorrhage, diarrhea, vomiting
intracellular volume varies with the effective osmolality of the _______ first. EX)
extracellular compartment first. i.e. sweating, diarrhea, fluid resuscitation, etc
Loss of hypotonic fluid, what happens to:
- ECF Vol
- ICF Vol
- Body osmolarity
- ex)
- decrease ECF
- decrease ICF
- Increase osmolarity
- dehydration, DI, Alcoholism
Gain of isotonic fluid, what happens to:
- ECF Vol
- ICF Vol
- Body osmolarity
- ex)
- increase ECF
- no change in ICF
- no change in osmolarity
- isotonic saline given
Gain of hypotonic fluid, what happens to:
- ECF Vol
- ICF Vol
- Body osmolarity
- ex)
- increase ECF
- decrease ICF
- decrease osmolarity
- hypotonic saline, water intoxication
if ECF osmolality decreases, cells _____ water and ____
if ECF osmolality decreases, cells gain water and swell
RAAS stands for
renin angiotensin aldosterone system
Gain of hypertonic fluid, what happens to:
- ECF Vol
- ICF Vol
- Body osmolarity
- ex)
- increase ECF
- decrease ICF
- increase osmolarity
On a D-Y diagram what do the compartments represent?
- right of the center black line (Y-axis) = ECF
- left of the center black line (Y-axis) = ICF
- top of diagram (horizontal line intersecting Y-axis) = osmolarity.
What are 2 primary factors that stimulate aldosterone
- Plasma angiotensin II (stimulates aldosterone release)
2. Plasma K+ (stimulates aldosterone release)
Aldosterone
- increases Na+ reabsorption in principal cells of kidney
- Na+ reabsorption plays a key role in regulating ECV
- regulates plasma K+ and increases the secretion of K+ in principal cells
angiotensinogen is converted to ___ by___
angiotensinogen is converted to ATI by renin
ATI is converted to ___ by ___
ATI is converted to ATII by ACE
ADH stimulates water reabsorption in principal cells of the kidney via
via the V2 receptor
- by regulating water ADH plays a pivotal role in regulating EC osmolality
- ADH also vasoconstrictor arterioles (V1 receptor)
- thus can serve as a hormonal regulator of vascular tone
primary regulators of ADH are
- plasma osmolality (directly related): increase stimulates, decrease inhibits
- BP/Vol (inversely related): increase inhibits; decrease stimulates
- (CRH) Corticotropin releasing hormone (directly related)
- Angiotensin II (directly related)
3 primary regulators of renin
- perfusion pressure to kidneys, reflex sympathetic stimulation (inversely related): increase inhibits; decrease stimualtes
- sympathetic stimulation to the kidney (direct effect via beta-1 receptors)
- Na+ delivery to the macula densa (inversely related): increase inhibits, decrease stimulates
ADH
- stimulates water reabsorption in principal cells of the kidney
- via the V2 receptor
- by regulating water ADH plays a pivotal role in regulating:
- EC osmolality
- ADH also vasoconstricts arterioles (V1 receptor)
- thus can serve as a hormonal regulator of vascular tone
if ECF [sodium] increases, what happens to the ICF
if ECF [sodium] increases, ICF volume decreases
- if if ECF [sodium] decreases, ICF volume increases
normal extracellular osmolality
approx 290 mOsm/kg (Osmolarity of 290 mOsm/L)
the main factor promoting filtration
capillary hydrostatic pressure
the main factor promoting absorption
plasma protein osmotic force
