Lecture Exam 3 - 34H) - 34I) Circulation and Gas Exchange – Mammals specifically humans Flashcards
• Atria has what kind of walls?
thin
• What does the atria do?
Receives blood into the heart to drive it into the ventricles
• The ventricles have what kind of walls?
thick
• So what does the Atrioventricular valve do? Specially How?
it prevents backflow between atria and ventricles – it closes in
• How are semilunar valves the 2 exit points from the heart?
Prevents backflow to the right ventricle
• What is the beat origin of the heart?
Via the SA node as an electrical impulse that causes the walls of the atria to contract
• If cardiac muscles are autorhythmic, what does this then mean?
No signals from the nervous system
• In the Cardiac Cycle, what is the difference between systole vs diastole? What else does it do?
Systole: Contraction – of the ventricles. Diastole: relaxation – of the arteries. Allows blood to move from our lungs to our heart to the rest of the body
• What is the Cardiac Cycle about?
About the complete sequence of pumping and filling
• In the Cardiac Cycle, what is the pace maker called? And what does it do?
Sinoatrial (SA) node which set the contraction for the cardiac muscle
• How does the atrioventricular (AV) node relay messages? Is it done on the top or bottom of the heart? Then where else?
Top – ventricles – b/c remember it prevents backflow back to the ventricles
• Arteries are much thicker wall so they are dealing with pumping of the ___
heart
• What are Endothelium?
are epithelial cells lining the central cavities
• How does Endothelium help with friction?
It decreases the amount of friction to allow blood to move through vessels – also, as we get older and build up plaque in our veins it decreases the amount of blood flow and becomes a problem
• Are Capillaries thin walled?
Yes
• Capillaries are the size of what?
red blood cells
• Do capillaries have endothelium?
They do - remember they are the walls of the Capillary beds, which are thin
• How does blood-interstitial fluid exchange within the Capillaries?
Due to the thin walls – where diffusion also takes place.
• what do red blood cells have to do with Capillary?
As red blood cells pass through the capillaries, they drop off the oxygen that your cells need to live, and pick up the waste gas, carbon dioxide
• In a capillary, what does the thin basal lamina surround?
The endothelium – it’s thin layered
• blood-interstitial fluid exchange only occur in Capillaries due to what?
The thin walls in Capillaries.
• What is the outer layer of Arteries & Veins?
elastic fiber, collagen connective tissue
• What is the inside layer of Arteries & Veins?
smooth muscle to allow smooth movement of blood; elastic fibers
• What does blood flow velocity do?
it slows arteries and arterioles – blood flow is slowest in Capillaries
• In Blood Flow Velocity, what is Vasoconstriction?
Results in the narrowing of the blood vessels/smooth muscles in arteriole walls contract & increases blood pressure up from where it occurs
However - the widening of blood vessels - is Vasodilation - blood pressure decreases
• So what is blood flow velocity –
moves slow when it moves into the arteries and then moves slower into arterioles then makes it way into the Capillaries
• How do smooth muscles in arteriole walls contract? Are they narrow?
They are narrow – as the smooth walls in the tunica media contract, it makes the lumen narrower
• In Vasodilation, do smooth muscles relax and open?
Yes
• In Vasodilation, what happens to blood pressure up from where it occurs?
it decreases blood pressure
