C33. Fluid shift across the capillary wall: Pulmonary and systemic oedema Flashcards
(42 cards)
what is the total body water amount
42 L (or 60% of body weight)
how much of the body water is extracellular
1/3 or 14L
how much of the extracellular fluid is interstitial
75% or 11L
what is interstitial fluid
fluid that fills the spaces between cells in the body and acts as the go between blood and body cells.
capillaries have how many layers of endothelial cells
one
what do capillaries do as a function
facilitate exchange
capillaries exchange using what methods
simple diffusion or convection
what is paracellular
through the cells themselves (as in material passes through the capillaries)
what is transcellular
movement of fluid between cells (through the gaps)
what are the 3 types of capillaries
continuous, fenestrated and sinusoidal (discontinuous)
what is exchanged at capillaries (2)
gases and water soluble substances
what cant be exchanged at capillaries
proteins
why cant proteins e exchanged at capillaries
too large in most capillary types
some fenestrated can facilitate a limited amount
what other structure can facilitate protein movement
pinocytic vesicles
are Water soluble substances lipid soluble
NO
are gases lipid soluble
yes
how do gases exchange through capillaries
Transcellular diffusion driven by partial pressure gradient and surface area available for exchange
how do water soluble substances move exchange through capillaries
Paracellular diffusion driven by solute gradient and surface area available for exchange
what is Starling’s forces equation
Jv=Kf [(Pc-Pi) - (𝜋c-𝜋i)]
what is starling’s forces
Imagine you have a sponge (the capillary) and a bowl of water (the interstitial fluid). The sponge can soak up water or squeeze it out, depending on the pressures.
Hydrostatic Pressure:
Capillary Hydrostatic Pressure (Pc): Think of this as the sponge being squeezed, pushing water out into the bowl.
Interstitial Hydrostatic Pressure (Pi): This is like the water in the bowl pushing back against the sponge.
Osmotic Pressure:
Capillary Oncotic Pressure (πc): Imagine there are tiny magnets (proteins) inside the sponge pulling water back into it.
Interstitial Oncotic Pressure (πi): There are also tiny magnets in the bowl pulling water out of the sponge.
The overall movement of water depends on which forces are stronger. If the squeezing force (Pc) is stronger than the magnets in the sponge (πc), water moves out. If the magnets in the sponge (πc) are stronger, water gets pulled back in.
explain Hydrostatic pressure:
1. Capillary hydrostatic pressure (Pc)
2. Interstitial hydrostatic pressure (Pi)
- fluid wants to move out
- fluid wants to move in
explain Osmotic pressure:
1. Capillary oncotic pressure (πc)
2. Interstitial oncotic pressure (πi)
- fluid being pulled into the capillary
- fluid being pulled out of the capillary
fluid going from lumen out to the interstitial space is referred to as….
filtration
fluid going from the interstitial space into the lumen is referred to as….
absorption