Lecture 14 - Capillary Exchange Flashcards
Name the three transport mechanisms of Capillary Exchange
Diffusion, Bulk Transport and Transcytosis
Formula for Net Filtration Pressure?
NFP = Net Hydrostatic Pressure - Net Osmotic Pressure
Formula for Net Hydrostatic Pressure?
NHP = Capillary Hydrostatic Pressure - Interstitial Fluid Hydrostatic Pressure
Formula for Net Osmotic Pressure?
NOP = Blood Colloid Osmotic Pressure - Interstitial Fluid Colloid Osmotic Pressure
What is the result of increased CHP (e.g. in hypertension)?
Increased NFP -> increased filtration, fluid collects in extremities, odoema
What is the result of decreased CHP (e.g. in haemorrhage)?
Decreased/negative NFP -> increased reabsorption, increased BP and CO
What is the result of increased BCOP (e.g. in dehydration)?
Decreased/negative NFP -> increased reabsorption
What is the result of increased ICOP (e.g. in tissue damage)?
Increased NFP -> increased filtration, local odoema
What is different about vasodilation and vasoconstriction in pulmonary circulation?
In lungs, arterioles Constrict when O2 Falls (to shunt blood to oxygen-rich areas)
In other organs, arterioles Dilate when O2 Falls (to aid oxygen delivery)
Three main differences in pulmonary circulation
- Lower Vascular Resistance (shorter, wider vessels)
- Lower CHP
- Arteries are more distensible (can take increased CO with very little pressure increase)
Why is coronary sometimes restricted, and at what stage does this restriction occur?
During systole, due to compression of Left Coronary Artery
How does the heart compensate for the restriction of coronary blood supply? (2 ways)
Cardiomyocytes have high O2 reserves
The myocardium has high capillary density for O2 extraction
What vasomotor change occurs in emergencies to maintain blood flow to the brain?
Vasodilation of cerebral vessels, and vasoconstriction of peripheral vessels
What is the approximate cerebral blood flow per minute (and is this relatively high or low?)
750ml/min -> high CO for the mass of the brain
How many arteries supply the brain, and where do they anastamose?
4, inside the cranium
