Valves and vessels Flashcards
(25 cards)
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
How are the capillaries adapted for exchange?
- Large cross sectional area
- blood flow is much slower
- thin walled
What are the 3 basic layers of arteries and veins?
Tunica intima
Tunica media
Tunica adventitia
What is the blood supply that supplies large arteries?
Vasa vasorum
Which layer is present in capillaries?
Tunica intima
Which branches come directly off the aorta?
Brachiocephalic trunk and subclavian arteries
Which arteries does the brachiocephalic trunk give off?
Common carotid arteries
Which vein drains from the head?
The internal and external jugular
Which veins combine to form the caudal vena cava?
Axillary vein and subclavian vein draining the forelimb and some of the intercostal area
Which muscle has the highest oxygen consumption?
Cardiac muscle
