Chapter 30

Compare and contrast the structure of the mitral and tricuspid valves

-Both have thin flaps secured to papillary muscles by chordae tendineae. -The right valve has three cusps; the left valve has two.

A proximal LAD lesion is a blockage in the left anterior descending artery, also known as the anterior interventricular artery. Explain why a heart attack caused by an obstruction of this artery is sometimes referred to as the "widow maker" heart attack

Because this is the most common cause of heart attack in men (inclusion of LAD)

Describe the unique anatomical features of cardiac muscle. What role does the unique structure of cardiac muscle play in its function?

Heart is a fully functional syncytium because of intercalated discs

How would you distinguish the structure of cardiac muscle from that of skeletal muscle?

One is branched one is not, one has communicating junction, one has tight junctions, one has 1 nucleus, the other has multiple nuclei

Trace drop of blood through the heart and lungs starting with right atrium

Right atrium Tricuspid valve Right ventricle Pulmonary valve Pulmonary trunk Pulmonary arteries Pulmonary capillaries Pulmonary veins Left atrium Mitral valve Left ventrical Aortic valve Aorta

Which valves close when cusps fill with blood?

Semilunar valves (aortic and pulmonary valves)

Knowing that structure and function are related, how would you say this structural difference reflects the relative functions of these two heart chambers?

The left ventricle pumps blood through the high-resistance systemic circulation; therefore, it has to be stronger than the right ventricle, which pumps blood through the short low-resistance pulmonary circuit

During the sheep heart dissection, you were asked initially to identify the right and left ventricles without cutting into the heart. During this procedure, what differences did you observe between the two chambers?

The left ventricle was firmer, thicker, and less compressible; the right ventricle felt "flabby."

Using your own observations, explain how the operation of the semilunar valves differs from that of the mitral and tricuspid valves.

When the ventricle was compressed (as in systole), the AV valve flaps moved superiorly into the closed position. When water was poured (as when blood backflows) into the semilunar valves, the cusps filled and closed the valve.

Mitral and tricuspid valves prevent backflow into the?

atria

receiving chambers of the heart

atria

tricuspid and mitral valves

atrioventricular valves

Which valves are anchored by the chordae tendineae?

atrioventricular valves (biscupid and tricuspid)

13

brachiocephalic trunk

Syncytium

can pass from one cell to the next

provide nutrient blood to the heart muscle

coronary arteries

drains blood into the right atrium

coronary sinus

lining of the heart chambers

endocardium

visceral pericardium

epicardium

29-50

left anterior descending branch of the left coronary artery

14

left common carotid artery

15

left subclavian artery

Location of the heart in the thorax

mediastinum

layer composed of cardiac muscle

myocardium

pulmonary and aortic valves

semilunar valves

Name the three vessels that deliver oxygen-poor blood to the right atrium

superior vena cava, inferior vena cava, and coronary sinus

Describe the role of the systemic circuit

the blood vessels that carry blood to and from all body tissues (nutrient and waste exchange)

Describe the role of the pulmonary circuit

the blood vessels that carry blood to and from the lungs (gas exchange)

When you measured thickness of ventricular walls, was the right or left ventricle thicker?

the left ventricle

What is the function of the fluid that fills the pericardial sac?

to reduce friction between 2 layers during pumping

Semilunar valves prevent backflow into the?

ventricles

discharging chambers of the heart

ventricles