A&P II Ch. 20 Heart Lab QUIZ

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

Skeletal muscle is long, cylindrical, multinucleated cells and has obvious striations. Cardiac muscle are branching, striated, usually have uni-nucleated cells that interdigitate at the junctions (intercalated discs).

Which is more serious, atrial fibrillation or ventricular fibrillation? Why?

Ventricular fibrillation is the most serious cardiac rhythm disturbance. The lower chambers quiver and the heart can't pump any blood, causing cardiac arrest. The heart's electrical activity becomes disordered.

fibrillation

Very rapid uncoordinated myocardial activity

The pulmonary veins carry blood to the

heart.

Figure 20-1 The Heart Use Figure 20-1 to answer the following questions: Which chamber receives oxygenated blood from the pulmonary circuit?

left atrium

Blood returning to the heart from the pulmonary circuit first enters the

left atrium.

The heart lies within the ________ cavity.

pericardial

Figure 20-1 The Heart Use Figure 20-1 to answer the following questions: Identify the structure labeled "19."

pulmonary semilunar valve

Describe what happens in the cardiac cycle in the following situations. during the T wave

repolarization of the ventricles

Describe what happens in the cardiac cycle in the following situations. immediately before the P wave

the heart is in diastole

List the elements of the intrinsic conduction system in order, starting from the SA node.

1. SA node 2. AV node 3. AV bundle (bundle of His) 4. left and right bundle branches 5. subendocardial conducting network (Purkinje fibers)

bradycardia

Heart rate below 60 beats/min

tachycardia

Heart rate over 100 beats/min

Why does heart rate increase during running?

In greater demand when our body is under that kind of strain, the heart must beat faster and harder in order to deliver the larger amount of blood to muscles being used when running.

Even though cardiac muscle has an inherent ability to b5555eat, the intrinsic conduction system plays a critical role in heart physiology. What is that role?

It ensures the heart muscle depolarizes in an orderly and sequential manner, from atria to ventricles, and that the heart beats as a coordinated unit.

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

It lubricates the heart, allowing the heart to beat in a relatively frictionless environment.

Describe what happens in the cardiac cycle in the following situations. immediately after the P wave

contraction of the atria

Describe what happens in the cardiac cycle in the following situations. immediately after the QRS complex (S-T segment)

contraction of the ventricles

Figure 20-1 The Heart Use Figure 20-1 to answer the following questions: Identify the structure labeled "6."

cusp of tricuspid valve

Describe what happens in the cardiac cycle in the following situations. during the P wave

depolarization of the atria

Describe what happens in the cardiac cycle in the following situations. during the QRS complex

depolarization of the ventricles and repolarization of the atria