Heart and cardiovascular system

Functions of heart

-generating blood pressure
-routing blood
-ensuring one-way blood flow

Epicardium

smooth outer surface of heart

Myocardium

middle layer composed of cardiac muscle cell and responsibility for heart contracting

Endocardium

smooth inner surface of heart chambers

function of musculi pectinati

increase the force of contraction in the atria of the heart

Function of trabeculae carnae

muscular ridges that make ventricular pumping stronger and more efficient

Arteries

• Carry blood away from the heart

• Usually carry oxygen-rich blood (except pulmonary arteries)

• Deliver oxygen and nutrients to body tissues

Veins

• Carry blood back to the heart

• Usually carry oxygen-poor blood (except pulmonary veins)

• Remove carbon dioxide and wastes from tissues

• Have valves to prevent backflow of blood

Veins

Have low oxygen levels

Arteries

have high oxygen levels

Function of coronary arteries

They supply oxygen-rich blood and nutrients to the heart muscle (myocardium) so the heart can keep contracting and pumping effectively

Function of great cardiac vein

Removes waste blood from the heart muscle and sends it back to the heart to be re-oxygenated

Function of small cardiac vein

It drains deoxygenated blood from the right side of the heart—mainly the right atrium and right ventricle—and carries it to the coronary sinus, which then empties into the right atrium

Function of coronary sinus

It collects deoxygenated blood from the heart’s cardiac veins (like the great, middle, and small cardiac veins) and drains it into the right atrium

Function of right atrium

Has 3 major openings that receive blood returning from body (superior vena cava, inferior vena cava, coronary sinus)

Function of left atrium

4 openings that receive blood from pulmonary veins

Function of atrioventricular canals

They are the openings between each atrium and its ventricle that allow blood to flow from the atria into the ventricles

Function of right ventricle

pumps deoxygenated blood into the pulmonary artery and to the lungs so it can pick up oxygen

Function of left ventricle

pumps oxygen-rich blood into the aorta and out to the entire body

Function of atrioventricular valves (AV)

Closes under pressure
Prevent backflow of blood from the ventricles into the atria during ventricular contraction

Ensure one-way blood flow through the heart

Function of semilunar valves

Opens under pressure
Prevent backflow of blood from the arteries into the ventricles after the heart contracts

Ensure one-way blood flow out of the heart into the aorta and pulmonary artery

Blood flow

superior and inferior vena cava → right atrium → tricuspid valve → left ventricle → pulmonary semilunar valves → pulmonary trunk → pulmonary arteries → lung → pulmonary veins → left atrium → bicuspid valve → left ventricle → aortic semilunar valve → aorta

Function of heart skeleton

1. Structural support

2. Electrical insulation

3. Valve functions

4. Force transmission

Function of intercalated discs

mechanically hold cardiac cells together and electrically connect them for coordinated, rhythmic contraction

Sinoatrial node (SA node)

Generate spontaneous action potentials. Those action potentials pass to atrial muscles cells and to the AV node

AV node

Action potentials conducted more slowly here. Ensures ventricles receive signal to contract after atria have contracted

AV bundle

Passes through hole in cardiac skeleton to reach interventricular septum

R+L bundle branches

Extend beneath endocardium to apices of left and right ventricles

Purkinje fibers

Conduct action potential to ventricular muscle cells