The Structure of the Heart Trivia Quiz

Answer: True

Rather like a love heart shape, the rounded part is the base and is situated at the top of the heart. The point, or apex, sits at the bottom. Though the heart is split into left and right sides, it does not sit straight up and down with these sides to their respective sides in the body. In fact, the heart sits on its right, with the right ventricle toward the front.

Answer: Visceral pericardium

As with most layers surrounding organs, the pericardium folds back over itself to produce a double layer. The visceral pericardium sits directly on top of the epicardium, which is a connective tissue layer over the heart muscle. The visceral layer then folds back over itself to become the parietal pericardium.

In between these layers is the pericardial cavity, which is a potential space - this means that in normal circumstances, it is not actually a space, but can fill up with fluid in disease states.

The visceral and parietal pericardia together form the serous pericardium. The fibrous pericardium lies on top of the serous pericardium, and is in fact inseparable from the parietal pericardium.

Answer: Atrioventricular (AV) node

There are four fibrous annuli (rings) in the heart that physically separate the atria from the ventricles. Asides from the left and right fibrous trigones, there is one annulus each for the aorta and the pulmonary artery. The annuli are important in causing a delay of the heartbeat as it travels from the atria to the ventricles - this is essential to allow them to contract at distinctly different times.

This makes it a good place for the AV node to be situated as it relays the heartbeat signal through the heart.

Answer: Right atrium

As the embryo gets its oxygen supply from the mother's blood via the placenta, there is no need for the embryonic blood to travel through the lungs, which is why the foramen ovale exists. Another cardiac shunt in the embyro is the ductus arteriosus, which connects the pulmonary artery to the aorta, bypassing the lungs.

The third shunt is the ductus venosus, which shunts blood from the umbilical vein to the inferior vena cava. This prevents oxygenated blood going to the embryonic liver.

Answer: Aortic valve

Valves are important in ensuring that the blood flow through the heart continues forward and does not lag, which would cause blood pooling and insufficient flow through the tissues. There are four heart valves - the ones offered as answers to this question; the tricuspid valve (situated between the right atrium and right ventricle), the pulmonary valve (situated between the right ventricle and pulmonary artery), the bicuspid valve (situated between the left atrium and left ventricle) and the aortic valve (situated between the left ventricle and aorta).

The valves in the great vessels are forced open by the pressure of ventricular contraction, while the atrioventricular valves are opened by atrial contraction. The closure of these valves is what produces the recognizable heart sounds: "lub dub".

Answer: Chordae tendineae

The chordae tendineae are also called the "heartstrings". As suggested by their name, they are tendons. As they connect the valves to the papillary muscles, when these muscles contract, the chordae tendineae transmit the resulting tension to the valves, causing them to open or close.

There are three papillary muscles in the right ventricle, one connecting to each cusp of the tricuspid valve, and two in the left ventricle, one connecting to each cusp of the bicuspid valve.

Answer: Right auricle

"Auricle" used to refer to what is now the atrium, so there was a right auricle and a left auricle - these are now the right atrium and left atrium respectively. Nowadays, "auricle" refers to the atrial appendages: they are small muscular pouches attached to the atria.

In the right ventricle, the conus arteriosus (also called the infundibulum) is the conical structure that is formed from the ventricle, and from which arises the pulmonary artery. The moderator band is a muscular band that carries the right bundle branch of the heart's conducting system to the anterior papillary muscle. Finally, the trabeculae carneae in the ventricles are similar to the pectinate muscles in the atria - they are rounded muscles on the inner surface of the ventricular walls. Their function is to prevent suction in the heart, and they also assist the papillary muscles.

Answer: Left

The posterior descending artery (PDA) supplies part of the interventricular septum, as does the left anterior descending artery (LAD), which arises from the left coronary artery.

If a coronary artery becomes blocked, dominance is very important in determining whether it ends in a heart attack or not. If the patient is left-dominant and their left coronary artery becomes blocked, both the PDA and LAD are blocked too, as both arise from the left coronary artery. This is very dangerous as there would be no blood supply to the septum. If the right coronary artery was blocked, only the PDA would be blocked, and the LAD would continue to supply the septum.

In right dominance, whether the left or right coronary artery is blocked, there will still be either the PDA or LAD supplying the septum. Luckily, most of the population is right-dominant (around 65-70%). Co-dominance can exist, where the PDA arises from both coronary arteries; figures vary from about 10-25% of the population. Left dominance also varies from about 10-25% of the population.

Answer: It is nearly always fatal.

Of all newborns born with a congenital heart defect, around 30-60% of them have a VSD. Many small VSDs can close on their own without medical intervention, and in fact the defect normally only manifests a few weeks after birth. First they are normally treated by drugs, and then they are repaired by surgery, though some can be repaired without surgery.

It can result after heart attacks due to tearing of the muscular wall of the septum.

It results in pulmonary hypertension because of the increased blood present in the right ventricle.

Answer: Widening of the pulmonary trunk

In fact, the condition causes pulmonary stenosis, which is a narrowing of the trunk, mostly caused by hypertrophy (overgrowth) of the heart muscle. Because the aorta sits over the septum, the level of oxygenated blood exiting the aorta to supply the body is decreased. The right ventricle hypertrophies as it works harder in order to try to oxygenate more blood. A ventricular septal defect decreases the level of oxygenation further.

The condition occurs in about 400 per million births, and can be repaired by surgery.