1. CV Review Flashcards
What is the basic function of the circulatory system?
Support cell metabolism by:
- delivering O2 and nutrients to cells
- removing CO2 and wastes from cells
By what mechanism are nutrients delivered by the circulatory system?
Diffusion
Over what distances is diffusion timely? Why?
Timely only over tiny distances (over large distances, diffusion is too slow to keep up w/ cells’ metabolic rates)
How is diffusion maximized?
- Larger surface area
- Minimal distance and membrane thickness
- Large concentration gradient
What is Fick’s Law of Diffusion?
Qx = rate of diffusion of X
D = diffusion coefficient
As = surface area for exchange
Δ[X] = concentration gradient
ΔL = diffusion distance
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What drives transcapillary solute movement?
Diffusion
How do capillaries affect Fick’s Law of Diffusion?
- Increases surface area for exchange
- Minimizes diffusion distance
How are capillaries made to maximize diffusion?
- Huge CSA
- Thin membrane wall
- Small diameter
- Large number throughout body
How are CSA and speed of flow in the CV system related?
Inversely:
- large CSA = slower flow
- small CSA = rapid flow
Why is it important for CSA and speed of flow in the CV system to have an inverse relationship?
Large CSA –> velocity slows –> allows more time for nutrient exchange
What is the basic function of the heart?
Develops the pressure gradient that creates flow of blood w/in the circulatory system
Over what distances is convection (bulk flow) timely?
Timely over large distances
Why is bulk flow (convection) important?
- Maintains the driving force for diffusion, so nutrients are coming in at a rate proportional to their leaving
- Shortens time b/t capillary beds –> speeds up diffusion
Define convection.
Bulk flow of blood around the circulatory system
How could one increase the delivery rate of a substance?
- Increase blood flow rate
- Increase concentration of substance in blood