Topic 11: Cardiovascular System - Capillary Exchange Flashcards
What is capillary exchange between?
blood and ISF
What three methods allow solutes to enter and leave capillaries?
- diffusion
- vesicular transport
- Mediated Transport
What is the role of diffusion in capillary exchange?
- major route, except for brain
Which ions and molecules can diffusion occur for in capillary exchange? (6)
- CO2
- O2
- ions
- aa
- glucose
- hormones etc
Between which cells does diffusion occur?
between endothelial cells
Which molecules is vesicular transport for?
large proteins (ie antibodies)
How does vesicular transport in capillary exchange occur? (3)
- via transcytosis
- endocytosis from blood into endothelial cell
- then exocytosis from endothelial cell into ISF
What does mediated transport require? (2)
- membrane carrier protein
- important mainly for brain
Through which mechanisms does fluid (water) enter/absorb or leave/filtrate capillaries? (2)
- osmosis
- bulk flow
Why does bulk flow allow for absorption/filtration in capillaries?
- due to pressure differences
What 4 pressures are involved in bulk flow of capillaries?
1) Blood hydrostatic pressure (BHP) - blood pressure
2) blood osmotic P (BOP) - due to plasma proteins
3) ISF hydrostatic P (IFHP) - 0 mmHg
4) ISF osmotic P (IFOP) - due to ISF proteins
Net filtration pressure (NFP) diagram
What is net filtration pressure? (2)
- sum of hydrostatic and osmotic pressures acting on the capillary
- across a capillary from arteriolar to venous end
Formula for net filtration pressure
Example given of NFP important
- negative means absorption