Chapter 19 practice quiz

Calcium channels in the nodal cells function to

An influx of calcium ions into a nodal cell causes depolarization.

From the left ventricle, where does blood pass?

Aortic semilunar valve

All of the following occur when the ventricles contract except

Blood from the pulmonary trunk travels to the lungs through the pulmonary arteries. Pulmonary veins then bring blood back to the left atrium.

Which of the following is the correct circulatory sequence for blood to pass through part of the heart?

Blood returning from the systemic circuit enters the right atrium from the superior vena cava, inferior vena cava, and the coronary sinus. It flows into the right ventricle through the right atrioventricular valve and then into the left ventricle. From the left ventricle, blood flows through the pulmonary semilunar valve and into the pulmonary trunk, which is the start of the pulmonary circuit.

Venous blood draining the heart wall (coronary sinus) enters the right atrium through the

Blood returning from the systemic circuit enters the right atrium from the superior vena cava, inferior vena cava. Blood returning from the coronary blood supply drains to the right atrium through the coronary sinus.

Why is it necessary to stimulate papillary muscles in the ventricle slightly earlier than the rest of the ventricular wall myocardium?

Contraction of the papillary muscles puts tension on the AV valve flaps through the chordae tendineae, thereby preventing prolapse of the valves and the subsequent backflow of blood into the atria.

This vessel distributes oxygenated blood to the myocardium.

Coronary artery

What occurs during the atrial reflex?

During the atrial reflex, increased venous return to the atria triggers sympathetic pathways that increase both the heart rate and force of contraction.

Which of the following consists of dense irregular connective tissue?

Fibrous pericardium

Action potentials are spread rapidly between cardiac muscle cells by

Gap junctions within intercalated discs allow calcium to flow across to adjacent cardiac muscle cells, thereby propagating the action potential.

Which of the below reduces heart rate.

Increased potassium levels

As each ventricle contracts where does blood move?

Into an artery

This part of the brain regulates heart rate.

Medulla Oblongata

Which layer consists of cardiac muscle tissue?

Myocardium

This electrical event triggers contraction of the atria.

P wave

This is used to reduce the friction between membranes of the heart.

Pericardial (serous) fluid

Which of the below valves prevents blood from flowing back from the lungs?

Pulmonary valve

Afterload is

Resistance in arteries during ejection of blood

This heart structure carries deoxygenated blood.

Right atrium and ventricle

This is the correct sequence of structures that allows the normal sequence of excitation to progress through the heart.

SA node, AV node, AV Bundle, Purkinje fibers

This term refers to the period of time during a cardiac cycle when contraction occurs and blood pressure rises.

Systole

This electrical event represents repolarization of the ventricle.

T wave

Why are there more myocardial cells creating the left ventricle wall compared to the right ventricle wall?

The blood ejected from the left ventricle needs to travel a further distance compared to the blood ejected from the right ventricle

The pericardial cavity is located between the

The pericardium is composed of two layers: a fibrous pericardium attached to both the sternum and the diaphragm, and an inner serous pericardium. The serous pericardium has two layers: a parietal layer that lines the inner surface of the fibrous pericardium, and a visceral layer, which covers the outside of the heart. The space between the parietal and visceral layers is the pericardial cavity.

Preload is the measure of

The preload is a function of the end-diastolic volume, and depends upon the amount of venous return of blood to the heart.

How is blood prevented from backflowing from the pulmonary trunk into the right ventricle?

The pulmonary semilunar valves prevent the backflow of blood from the pulmonary trunk, back into the right ventricle.

To which side of the body is the apex pointed?

To the left

Through which structure does blood pass from the right atrium to the right ventricle?

Tricuspid valve

Stimulation of this nerve reduces heart rate.

Vagus nerve

Which of these periods represents greatest cardiac output?

Ventricular systole