Diffusion and Convection Flashcards
What does gravity influence?
hydrostatic pressure
What is the equation for pressure?
P= ugh
P=pressure
g=constant
h=height
When standing up what happens to the pressure at the head compared to the heart?
MAP is lower
What happens to pressure when lying down?
similar in the head and the feet (MAP is similar)
What is convection?
bulk flow of fluid from an area of higher pressure to lower pressure
What is diffusion?
movement of molecules from an area of higher concentration to an area of lower concentration
What type of transport occurs in the trachea?
convection
What type of transport occurs in the bronchioles?
diffusion
Transport in aorta?
convection
Transport in capillaries?
diffusion
What are the factors affecting diffusion?
- surface area
- thickness of diffusion barrier
- diffusibility
- partial pressure gradient
What is more diffusible CO2 or O2?
CO2 is 20x more diffusible than O2
What is crucial to drive diffusion?
the partial pressure of O2 and CO2 (can be changed, other factors are constant)
What happens to the full equilibration of O2 during exercise?
- Blood flow rate increased
- full equilibration achieved
- decreased diffusion reserve
At rest, how far along the capillary is full equilibration of oxygen reached?
one third of the distance along the capillary
What happened to full equilibration of O2 at rest when the diffusion barrier is thickened?
-full equilibration of O2 at a further distance along the capillary
What happened to full equilibration of O2 during exercise when the diffusion barrier is thickened?
-full equilibration not achieved
What happened if you decrease the partial pressure gradient e.g at altitude to the equilibration of O2?
- decreased partial pressure gradient (slow rate of diffusion)
- takes longer to equilibrate
- full equilibration of O2 but at a lower PO2
- decreased O2 in the blood
How do you minimise diffusion distance in tissues?
by having a large number of capillaries
What do high metabolic tissues have more of?
capillaries
The the tissue how is the concentration gradient maintained?
by adequate blood flow
What do the elastic arteries convert intermittent flow into?
continuous flow
