General Fluid Movement Flashcards
Do the levels of body water change over the lifespan? If yes, how so?
Yes, they decrease over the lifespan
Describe the relative volumes of the three body fluids?
Plasma - 3L
Interstitial fluid - 10L
Intracellular fluid - 28L
What is the primary component of the body?
Water
Lean body mass vs. adipose tissue
Which has a higher % of water?
Lean body mass
What makes up lean body mass?
Muscles, organs, bones
The more fat present in the body…
…the less total water content
In older adults, the body water content is lower as a result of…
…decreased body mass
1L of water = _Kg
1L of water = 1Kg
For example, if a patient drinks 240 mL of fluid, weight gain will be:
0.24 kg
What are electrolytes?
Substances whose molecules dissociate or split into ions when placed in solution
What is the charge of most proteins?
Negtaive
What are cations?
Positively charged electrolytes
What are anions?
Negatively charged electrolytes
The overall concentration of the electrolytes is approximately the ___ in the two compartments (ICF & ECF)
the same
Main cation and anion in the ECF?
Cation - Sodium
Anion - Chloride
Main cation and anion in the ICF?
Cation - Potassium
Anion -Phosphate
What are the four pressures that control movement of fluid between capillaries and insterstitum?
- Capillary hydrostatic pressure
- Plasma oncotic pressure
- Interstitial hydrostatic pressure
- Interstitial oncotic pressure
What does Capillary hydrostatic pressure do?
Pushes fluid out of the capillaries
What does Plasma oncotic pressure do?
Pushes fluid into capillaries due to plasma proteins
What does Interstitial hydrostatic pressure do?
Pushes fluid into the capillaries
What does Interstitial oncotic pressure do?
Pull fluid out of capillaries
What is the capillary hydrostatic pressure on arterial and venous side?
Arterial - 40 mmHg
Venous - 10 mmHg
What is the plasma oncotic pressure?
25 mmHg
Which two pressure cause the movement of water out of the capillaries?
Capillary hydrostatic pressure
Interstitial oncotic pressure
Which two pressure cause the movement of fluid into the capillaries?
Plasma oncotic pressure and interstitisal hydrostatic pressure
What are four ways edema can develop?
- Lymphatic outflow is obstructed
- Elevation of venous hydrostatic pressure
- Decrease in plasma oncotic pressure
- elevation of interstitial oncotic pressure
What is happening in elevation of venous hydrostatic pressure?
Increasing the pressure at the venous end of the capillary inhibits fluid movement back into the capillary
Causes:
Fluid overload
HF
Liver failure
What is happening in decrease in plasma oncotic pressure?
There isn’t enough pressure to push the fluid back into the capillary so fluid remains in the interstitium
This is usually seen when there is low plasma protein content
This can be caused by:
Excessive protein loss - renal disorders
Deficient protein synthesis - liver disease
Deficient protein intake - malnutrition
What is happening when there is an elevation of interstitial oncotic pressure?
This occurs when there is damage to the capillary walls (inflammation, burns, etc.), proteins from the blood leak into the interstitial space, causing more fluid than normal to leak into the interstitial space, causing swelling
Fluid movement between the ECF and the ICF is driven by differences in ___
Osmolarity
Increased ECF osmolarity is a water __ in the cells
deficit
Decreased ECF osmolarity is water __ in the cells
excess
Changes in the osmolarity of the ECF alters the volume of the __
cells
What happens during increased ECF osmolarity?
Water is pulled out of the cells until the two compartments have similar osmolarity, causing cell shrinkage as water is pulled into the vascular system
What happens during decreased ECF osmolarity?
Water is pulled from the ECF into the cells, causing then to swell
What body system shows symptoms first with increased/decreased ECF osmolarity?
And as a result of what?
Neurological symptoms
As a result of brain swelling (in decreased ECF osmolarity)
What is fluid spacing?
A term used to describe the distribution of body water
What is first spacing?
Describes the normal distribution of fluid in the ICF and ECF compartments
What is second spacing?
Refers to an abnormal accumulation of interstitial fluid (edema)
The fluid is still part of extracellular fluid and can potentially be reabsorbed into the bloodstream or removed with treatment.
This fluid is abnormal, but still accessible to the body.
It’s not permanently “trapped”
What is third spacing?
Occurs when fluid accumulates in a portion of the body from which it is not easily exchanged with the rest of the ECF
This fluid is trapped and essentially unavailable for functional use
Serious complication of third-spacing
Hypovolemia
Examples of third-spacing
Ascites
Sequestration of fluid in the abdominal cavity with peritonitis
Edema associated with burns, trauma, or sepsis
