3.3.1 Regional Circulations Flashcards
Which organs require the largest amount of blood flow during rest?
Brain, Heart, Liver and Kidney
What is the equation for flow to an organ?
Why does resting blood flow differ between organs?
Resting blood flow to organs varies because of differences in vascular resistance between organs
When completely dilated which organ had the greatest increase in blood flow? Which has the least?
The skeletal muscle had the greatest increase, but heart is 5-fold.
Kidney had the lowest.
What organs rely mainly on local control of blood flow?
The heart and the brain.
What is oxygen uptake and what is the equation for it?
What can increase the oxygen uptake for an organ?
Opening of precapillary sphincter will increase the number of perfused capillaries.
What is the direct Fick Method and what is it’s equation?
Why is the heart able to consume so much more of the circulating oxygen than other tissues? How does this compare to the kidney?
What is autoregulation?
What allows for the brain and heart to maintain nearly constant flow? How does this compare to systemic organs?
What are the mechanisms for autoregulation?
What is the myogenic response and what is its pathway?
What is the metabolic hypothesis?
Vasodilator metabolites are produced by cells of many organs. Interstitial concentrations of these are determined by rate of formation and rate of removal.
What is the result of increased local metabolites? Will this change TPR significantly?
What is the role of adenosine as a vasodilator metabolite?
Adenosine levels rise wen ATP formation is impaired. Adenosine freely diffuses out of a cell and is a potent vasodilator.
How does potassium act as a vasodilator metabolite?
Potassium plays a major role in local regulation of blood flow in electrically organ such as the brain and heart. When the frequency of action potentials increases, the interstitial concentration of K+ rises. This local hyperkalemia causes hyerpolarization of arterioles within these organs, which decreases Ca++ influx to vascular smooth muscle, and causes relaxation.
How does lactic acid act as a vasodilator metabolite?
Increased interstitial levels of lactic acid and CO2 occur when O2 demand exceeds O2 availablility.