Introduction Flashcards
Where does the heart pump blood to?
The left side of the heart pumps blood to the body and the right side pumps blood to the lungs.
How do the muscle cells of the heart receive their nutrients?
The hearts own blood supply - the coronary arteries.
How do substances move between blood and tissues?
This all occurs by diffusion. Oxygen and carbon dioxide can move through the bilayer and other molecules move through small pores. Glucose and amino acids can pass through aqueous pores between endothelial cells.
What can affect diffusion rate?
Area - this is maximised by the capillaries, diffusion resistance and conc gradient - maximised and maintained.
What does diffusion resistance include?
Nature of molecule, nature of barrier, diffusion distance.
What does the effect of changing rate of blood flow have on concentration gradient for diffusion?
An increased blood flow rate increases the concentration gradient and so drives O2 into tissues.
What is perfusion rate?
This is the rate of flow of blood. More metabolically active tissues require a higher perfusion rate.
What is the cardiac output for a 70kg man at rest?
5L
State which organs require a constantly high perfusion rate.
The brain, the kidneys
In what circumstances is rate of blood flow to the skin changed?
When functioning for thermoregulation.
What changes occur to perfusion of organs during exercise?
There is decreased blood flow to the gut and increased flow to skeletal muscle and also into the coronary arteries.
What is responsible for control of perfusion to different organs?
Arterioles and pre capillary sphincters.
What is the capacitance of veins?
This is their ability to store blood. This allows for increased blood flow to occur when it is needed.
Why do we need a CVS?
Our bodies are too big to be able to adequately transport nutrients and gases by simple diffusion.
