Pathophysiology Exam 1 Flashcards
ICF
intracellular fluid
ECF
extracellular fluid
What determines solution concentration?
amount of water and solute
Solute =
Na+ (there are more, but most important)
Where does water move when the ICF & ECF are at equilibrium?
Water doesn’t move; no net water movement/fluid shift
Normal fluid concentration range
280-300
Isotonic
normal concentration
Hypertonic
more concentrated, less dilute
Hypotonic
less concentrated, more dilute
Hypertonic caused by:
decrease water or increase solute or both
Hypotonic caused by:
increase water or decrease solute or both
Most common cause of hypertonic ECF
water loss
What happens to the cell when the ICF is isotonic and the ECF is hypertonic?
It shrinks
water always moves where?
from dilute to concentrated
What happens to the cel when the ICF is isotonic and the ECF is hypotonic?
It swells/expands
the total of all the water in the body
total body water (TBW)
ICF is what fraction of TBW?
2/3
ECF is what fraction of TBW?
1/3
ECF two compartments
1) Interstitial fluid (btw cells)
2) Plasma (bloodstream)
IF constitutes how much of the ECF?
80%
Plasma constitutes how much of the ECF?
20%
- pressure trying to push water out of the bloodstream
- established by BV
Plasma hydrostatic pressure
- pressure trying to keep or attract water into the bloodstream
- established by albumin
Plasma oncotic pressure
What causes water movement between the ECF compartments?
plasma hydrostatic and oncotic pressure
If hydrostatic pressure = oncotic pressure then what?
water doesn’t move
Is BV at the arterial and venous ends of the capillary bed remain stable?
yes
accumulation of fluid in interstitial space
- distribution problem
Edema
4 factors that favor Edema formation
1) increase plasma hydrostatic pressure (increase BV)
2) decrease oncotic pressure (decrease albumin)
3) increase capillary permeability (increase leakiness)
4) Lymphatic obstruction
What can cause plasma hydrostatic pressure to increase?
anything that increases BV
- CHF; causes fluid retention, which increase BV
What can cause plasma oncotic pressure to decrease?
anything that decreases albumin
- liver failure
- protein malnutrition or protein absorption problem
What can cause capillary permeability to increase?
- inflammation: cells pull apart
- Trauma: direct vessel damage
What can cause lymphatic obstruction
- internal blockage
- external compression of lymphatic damage
Both: prevent drainage, leading to fluid accumulation
charged ionized particles
electrolytes
Normal blood Na+
135-145
Water follows what?
Na+
- emia
in blood stream
Hypernatremia
Na+ > 145
- 160 = severe
Hyponatremia
Na+ < 135
- <125 = severe
Most abundant ECF electrolyte
Na+
What do Na+ abnormalities impact?
ECF osmolarity & BV/BP
What regulates Na+ homeostasis?
GI tract, kidneys & endocrine system (aldosterone)
- most common in hospitalized patients & elderly
- almost always caused by decrease in water
- ECF becomes hypertonic
- Cells shrink
- In severe cases: CNS cells are damaged
Hypernatremia
- results from decrease Na + or increase water
- ECF becomes hypotonic
- Cells swell
- In severe cases: brain swells
Hyponatremia
What are common causes of hyponatremia?
- diuretic use
- diarrhea: decrease Na & decrease BV
- heart failure: increase water & increase BV
How should Hyponatremia be treated?
treated slowly: No more than 8 mEg/L of sodium in 24 hours
- rapid treatment could cause severe brain damage
Normal blood K+
3.5-5
What 2 hormones regulate K+?
1) aldosterone
2) insulin