Altered Cell Environment
Ends in View
Alterations in Tonicity
Alterations in K & Ca
What is edema?
an excessive accumulation of fluid within the interstitial spaces (too much water in that space)
To understand this, we have to go back to anatomy..
How is the fluid in the interstation regulated?
Green stars on slide 4
Capillary w/ an arteriole and venule (capillary bed)
a cell is supposed to receive water and nutrients from the capillary
What pressures regulate the amount of water that`s supposed to be in the interstition?
Capillary hydrostatic pressure
water that comes into the capillary from the arteriole)
this pressure pushes the water as a filtrate into the interstation
the higher the BP the more filtration, lower and lower
it is all dependent on BP
Capillary Oncotic Pressure
what is oncotic pressure? —osmotic pressure induced by proteins in the plasma
in the venules, there are a lot of proteins in the plasma
these proteins exert some osmotic pressure to attract water back into the venule from the interstation
this induces reabsorption of the water that was filtered back INTO the venule
this is dependent on the concentration of proteins in the plasma, NOT BP!
low protein in plasma = low oncotic pressure therefore less water reabsorbed.
In conclusion …
these 2 pressures regulate the movement of water from the arteriole into the insterstition then back into
the venule ... like a constant shower!
this filtered water brings nutrients and the reabsorbed water gets rid of waste
What About the Lymphatics??
the role of this is to pick up any excess of interstitial fluid that the venule did not pick up
when this get reabsorbed, it is called lymph Net Pressures
capillaries will filter water into the insterstition and the venous capillary will reabsorb (physiology)
Why Can Edema Happen
increased capillary hydrostatic pressure; whenever there is too much pressure inside the capillaries,
for example when there is too much salt OR heart failure, there will be excess filtration of the water into
the interstation, fluid movement into the tissue, causes edema (blood vessels with TOO much hydrostatic
pressure, may be veins or arteries)
decreased capillary oncotic pressure; whenever there is a decrease in the amount of plasma proteins,
there will be a decrease in oncotic pressure, therefore edema because there will not be enough osmotic
pressure to attract the water to be reabsorbed back into the blood vessel (this may happen in liver disease,
as well as malnutrition!)
increased capillary permeability; whenever there is vasodilation or whenever the blood vessels have
been damaged (burns), too much water escapes, plasma proteins are lost, both combine to produce edema
lymphatic obstruction; some diseases in which this happens, lymph nodes are damaged by tumor or
inflammation (most common cause), then you will see an excess of interstitial fluid that was supposed to
be reabsorbed by lymph will not be reabsorbed
Lymphedema; edema caused by lymphatic obstruction,
Pulmonary edema; when it happens, water accumulates in the alveoli, causes death fast because it
impedes the alveoli
Pleural/Pericardial effusion; edema not in the interstitial face but it’s in the cavities
Pleural; the lungs, accumulates in the pleura
Pericardial; effusion in the pericardial cavity
Ascites; effusion but in the peritoneal cavity
Dependant edema; edema that occurs in the areas that are lower in the gravity, if they’re sanding and
they may get edema in their legs and feet, laying down edema in back and buttocks
Pitting edema; when a person is swollen and you touch it your handprint stays
Third space edema; implies that there can be edema in the first space and second space (which are the
intravascular and extravascular compartments), third space is another compartment where there is
normally not a lot of water such as in the intestine (obstruction), can cause dehydration
Cerebral edema; happens often after trauma, ve