C33. Fluid shift across the capillary wall: Pulmonary and systemic oedema Flashcards
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
Explain Hydrostatic pressures - Capillary hydrostatic pressure (Pc)
Why? and which end ha the most?
- Favours filtration
Product of arterial and venous pressures
Highest at arterial end of capillary and falls along length
Explain Hydrostatic pressures-Interstitial hydrostatic pressure (Pi)
how large is the pressure
○ Opposes filtration
○ Normally single digit values or slightly negative
explain oncotic pressures -
Capillary oncotic pressure (πc)
(presence….. proteins?)
○ Opposes filtration
○ Product of presence of proteins in capillary lumen
explain oncotic pressures - Interstitial oncotic pressure (πi)
○ Favours filtration
○ Product of presence of proteins in the interstitial fluid
what does the lymph system do?
returns fluid from the interstitial fluid to the circulation
Via what does the lymphatic system returns fluid from the interstitial fluid to the circulation?
lymphatic capillaries
where do the lymphatic capillaries return the interstitial fluid to wards
the thoracic duct and into the great veins
what do lymphatic capillaries contain
valves
how does changes to starlings forces effect anything (thing of swelling)
Increased Capillary Hydrostatic Pressure (Pc):
What it means: Imagine squeezing a hose harder. More fluid gets pushed out.
Effect: More fluid leaves the capillaries and enters the tissues, which can cause swelling.
Decreased Capillary Oncotic Pressure (πc):
What it means: Think of the magnets inside the hose (proteins) getting weaker.
Effect: Less fluid is pulled back into the capillaries, so more fluid stays in the tissues, leading to swelling.
Increased Capillary Permeability:
What it means: Imagine the hose has more holes in it.
Effect: More fluid and proteins can leak out into the tissues, causing swelling and inflammation.
Decreased Lymphatic Drainage:
What it means: The side streets (lymphatic system) are blocked or not working well.
Effect: Extra fluid in the tissues isn’t being removed properly, leading to swelling
explain pulmonary circulation in regards to resistance, capillary hydrostatic pressure, capillary osmotic pressure and lymphatic drainage
Pulmonary Resistance:
What it means: The resistance (or difficulty) for blood to flow through the lungs is much lower than in the rest of the body.
Effect: Blood can flow easily through the lungs.
Pulmonary Capillary Hydrostatic Pressure:
What it means: The pressure inside the tiny blood vessels in the lungs is low (about 8-11 mmHg).
Effect: This low pressure helps prevent fluid from leaking out into the lung tissues.
Capillary Osmotic Pressure:
What it means: The pressure created by proteins in the blood that pull fluid back into the capillaries is about 25 mmHg.
Effect: This helps keep fluid inside the blood vessels and prevents it from leaking into the lung tissues.
Efficient Lymphatic Drainage:
What it means: The lymphatic system in the lungs works well to remove any extra fluid that does leak out.
Effect: This prevents fluid from building up in the lung tissues, keeping them clear and healthy.
what is Oedema
Oedema is when fluid builds up in the spaces between cells, causing swelling. There are different types of oedema depending on where the fluid accumulates.
what is pulmonary oedema
fluid accumulation in the interstitial spaces of the lung
what are some symptoms of pulmonary oedema
Symptoms: This can cause difficulty breathing (dyspnoea) and low oxygen levels (hypoxia).
what is Peripheral Oedema?
Fluid builds up in the legs or other parts of the body.
what are some symptoms of peripheral oedema
Symptoms: This causes swelling in the affected areas, like the legs.
what is it called when Fluid builds up in the legs or other parts of the body.
peripheral oedema
what kind of medication is used to treat oedema and why
Diuretics are medications that help the body get rid of excess fluid by making you urinate more.
what patients do u give fluid to always
severe burns victims
