Chapter 8: Cardiovascular System Flashcards
What composes the cardiovascular system?
The heart and blood vessels. When this system fails, life at the cellular level isn’t possible and death occurs.
Define leaflets
Flat, leaf-shaped structures that comprise the valves of the heart and prevent backflow of blood.
Define lumen
Tubular space or channel within an organ or body structure; space within an artery, vein, intestine, or tube.
Define regurgitation
Backflow or ejecting of contents through an opening.
Define sphincters
Circular muscles found in a tubular structure or a hollow organ that constrict/dilate to regulate passage of substances through its opening.
Vasoconstriction
Narrowing of the lumen of a blood vessel that limits blood flow, usually as a result of diseases, medication, or physiological processes.
Vasodilation
Widening of the lumen of a blood vessel caused by the relaxing of the muscles of the vascular wall.
Viscosity
Thickness or measure of how resistant a liquid is to flowing. High viscosity = thick and slow-flowing.
3 major types of blood vessels
arteries, capillaries, and veins.
Function of arteries:
Carry blood from the heart to the body’s cells. Arteries carry blood with a high concentration of O2; only exception is the pulmonary artery.
3 layers of artery walls:
tunica externa, tunica media, tunica interna.
Tunica externa
Outer layer of the artery wall, composed of connective tissue that provides strength and flexibility.
Tunica media
Middle layer of the artery wall, composed of smooth muscle, which can alter the size of the lumen of the vessel; either vasoconstriction or vasodilation.
Tunica interna
Inner layer of the artery wall, composed of endothelial cells that create a smooth surface on the inside of the vessel.
Define pulse
A surge of blood felt in the arteries when blood is pumped from the heart.
Function of capillaries:
Microscopic blood vessels that join the arterial system with the venous system. Walls are composed of only a single layer of epithelial cells to allow for O2/CO2 exchange between the cardiovascular system and body cells.
Function of precapillary sphincters:
Regulate blood flow into the capillaries. When more blood is required in a tissue they open and they close when less blood is required in a tissue.
Function of veins:
Return deoxygenated blood to the heart; blood in these vessels has a characteristic purple color due to lack of O2. Blood in the veins contains a high concentration of CO2, with the exception of the pulmonary vein.
Methods used by veins to return blood to the heart (4):
1) Skeletal muscle contraction
2) Gravity
3) Respiratory activity
4) Valves
Define valves:
Small structures within veins that prevent backflow of blood. Found mainly in the extremities and are important for returning blood to the heart from the legs.
Function of the heart:
Muscular pump that propels blood throughout the entire body through a closed vascular network.
Pulmonary circulation
Occurs on the right side of the heart and delivers blood to the lungs, where CO2 is exchanged for O2.
Systemic circulation
Occurs on the left side of the heart and delivers blood to the body tissues, where O2 is exchanged for CO2.
What’s the pericardium?
A sac that encases the heart and is composed of 3 distinct layers; the epicardium, myocardium, and endocardium.