Basic structure and function of the heart

Question 1

Explain where the heart is located in the chest and what the main function of the heart is. (2)

Answer 1

1. Located between the lungs in the middle of the chest, behind the sternum and slightly to the left

• The function is to act as a pump, driving blood through the vasculature to deliver: Oxygenated blood to organs and tissues and Deoxygenated blood to the lungs for gaseous exchange

Question 2

Identify the four chambers and four valves of the heart. (8)

Answer 2

• 2 atrium (right and left)
• 2 ventricles (right and left)

1. Tricuspid valve - between right atrium & right ventricle, tri-leaflet (three flaps)
2. Pulmonary valve - between right ventricle & pulmonary artery, tri-leaflet (three flaps)
3. Mitral valve - between left atrium & left ventricle, bi-leaflet (two flaps)
4. Aortic valve - between left ventricle & aorta, tri-leaflet (three flaps)

• Mitral and tricuspid valves can be referred to as atrioventricular valves
• Pulmonary and aortic valves can be referred to as semilunar valves

Question 3

How does blood return to the heart, move within the heart and leave the heart, recognising when the blood is oxygenated or deoxygenated. (5)

Answer 3

1. Deoxygenated blood returns from the rest of the body and enters the right atrium (atrial diastole) via the superior and inferior vena cava
2. Deoxygenated blood flows from the right atrium (atrial systole) into the right ventricle (ventricular diastole) when the atrium contracts & the tricuspid valve opens (pulmonary valve closed)
3. Deoxygenated blood travels to the lungs via the pulmonary artery when the right ventricle contracts (ventricular systole) & the pulmonary valve opens (tricuspid valve closed).
4. Oxygenated blood returns via the pulmonary vein into the left atrium (atrial diastole)
5. Oxygenated blood flows from the left atrium (atrial systole) into the left ventricle (ventricular diastole) when the atrium contracts & the mitral valve opens (aortic valve closed). Oxygenated blood travels to the rest of the body via the aorta when the left ventricle contracts (ventricular systole) & aortic valve opens (mitral valve closed)

Question 4

Define diastole and systole (2)

Answer 4

Diastole = when a chamber of the heart relaxes allowing blood in

Systole = when a chamber of the heart contracts, forcing blood out

Question 4

How is the electrical system of the heart essential for contraction of the heart chambers (3)

Answer 4

The heart has its own electrical system that is key to cause the chambers to contract:

1. Electrical stimulus generated by sino-atrial node (natural pacemaker)→ atria contract
2. Electrical activity hits the atrioventricular node and travels down the bundle of His (branches into left and right) and along the Purkinje fibres
3. ventricles contract

Question 5

How does the heart have its own supply of blood (3)

Answer 5

• The heart is a muscle and needs its own blood supply for oxygen and nutrients
• The coronary arteries supply the heart with blood, these sit on the epicardium (outside the heart)
• The main coronary arteries are the left coronary artery and right coronary artery and these divide into branches

Question 6

Which valves of the heart can be described as tri-leaflet (3)

Answer 6

Aortic valve
Tricuspid valve
Pulmonary valve

Question 7

which arteries supply the heart with its own supply of blood

Answer 7

coronary arteries

Question 8

what is the role of the pulmonary artery

Answer 8

carry deoxygenated blood away from the heart to the lungs

Question 9

what is the name of the valve located between the right atrium and the right ventricle

Answer 9

tricuspid valve