Valves and vessels Flashcards
What is the function of the valves?
Ensure blood flows in the correct direction by opening to allow blood through and closing to prevent backflow
How are the valve cusps joined to the heart wall?
By chordae tendinae to muscular projections on the walls called papillary muscles
What is the function of the annulus fibrosis?
Provides support to the valves and serves as electrical insulation between the atria and the ventricles
What causes the valves to open and close?
Changes in pressure
How does the pressure change during isometric relaxation?
The pressure in the ventricle falls below the pressure in the atrium
How does the pressure change during isometric contraction?
The pressure in the ventricle rises above the pressure in the aorta(left)/pulmonary artery(right)
What is incompetence in the heart?
Failure of the valves to close properly
How do lipid and water soluble molecules diffuse through capillaries?
Lipid = directly through the bilayer Water = via pores between the endothelial cells
Which types of artery are found nearest the heart?
Large elastic arteries
What is the function of the precapillary arterioles?
Act as a precapillary sphincter zone regulating the blood flow into the capillary bed.
What is collateral circulation?
Most arteries give off side branches as a safety net in case of blockage of the main trunk.
- accommodate increased blood flow when the main route is compromised
What is the name of arteries without collateral circulation?
End arteries
What is diapedesis and where does it occur?
The means by which white blood cells move out of the circulation and into tissues to fight infections.
In the post-capillary venules
What is the most direct route between an arteriole and venules that enables a capillary bed to be shut off?
Arteriovenous anastomosis
How does blood flow in veins?
Passively
