TOPIC 1

Group A

• The heart pumps blood throughout the entire body

• The heart beats approximately 72 beats per minute supplying cells of the body with nutrients they need to survive

• When looking at an image, the right and left are defined as the right and left of the patient.

• This means right and left are reversed when looking at an image.

• In this image of the heart, “right” is to the left of the image and “left” is to the right of the image.

LEFTRIGHT

The Heart Contains Four Compartments:

2 Atrial and

2 Ventricular Compartments

Atrial Compartments of the Heart

The atria of the heart are receiving chambers. The right atrium receives blood from the body via the superior and inferior vena cava and the left atrium receives blood from the lungs via the pulmonary veins. The SA node is also contained within the right atrium and is the site at which electrical impulse to the heart originates.

Fossa Ovalis

Right Atrium

PectinateMuscle

AtrialCompartments

The atrial chambers contain pectinate muscles within the walls of the chamber. Blood passes from the atria to the ventricles through a one-way opening called the atrioventricular valve.

Ventricular Compartments of the Heart

RightVentricle

VentricularCompartments

Trabeculae Carneae Muscle

PapillaryMuscle

The ventricles are the discharging chambers. The right ventricle pumps blood away from the heart to the lungs via the pulmonary arteries and the left ventricle pumps blood away from the heart to the body through the aorta.

The ventricular chambers contain trabeculae carneae muscle. Ventricular chambers are more muscular and larger in size because they must pump blood away from the heart into a system under higher pressure, the pulmonary arteries or aorta. The left ventricle is the most muscular since it functions to pump blood to the entire body via the aorta.

As blood fills the atria, the pressure rises and forces the blood into the ventricle through the one-way atrioventricular valve. The period of ventricular filling is called diastole in the cardiac cycle. When a physician listens with a stethoscope, the ventricle filling with blood sounds like a “lub”. When the ventricles fill, an electrical impulse signals them to contract to push the blood into the pulmonary artery (right ventricle) or into the aorta (left ventricle). This period of ventricular contraction is called systole in the cardiac cycle. When a physician listens with a stethoscope, the ventricle squeezing blood out of the heard sounds like a “dub”.

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The right atrium receives deoxygenated blood from the body

Blood then flows to the right ventricle and is pumped to the lungs to become oxygenated

Blood Flow in the Heart

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5Oxygenated blood from the lungs is brought back into the heart and deposited into the left atrium

Blood then flows into the left ventricle

Oxygenated blood is then distributed to the body via the aorta

To The Body

The septa of the heart divide the left and right sides of the heart. There are two types of septa in the heart: the thin, membranous septum between the right and left atria and the thick, muscular septum between the right and left ventricles. Both septa help to maintain deoxygenated blood on the right side and oxygenated blood on the left side of the heart. The atrial and ventricular compartments remain divided by valves known as the tricuspid and mitral valves.

Interventricular Septum

Interatrial Septum

The tricuspid valve is found in between the right atrium and the right ventricle. It is called tricuspid because it has three cusps. The mitral valve is found in between the left atrium and the left ventricle and has two cusps. Both valves prevent backflow of blood into the preceding atrium. The papillary muscle within the walls of the ventricles attach to either the tricuspid or mitral valve and help to regulate the opening and closing of the valves.

Mitral ValveTricuspid Valve

Pulmonary Valve

• The pulmonary valve is found in between the right ventricle and the pulmonary artery leading to the lungs.

• The pulmonary valve contains three cusps.

• The pulmonary valve helps to regulate blood flow into the lungs.

PulmonaryValve

Aortic Valve The aorta is the largest

blood vessel in the body. Blood passing from the left

ventricle to the aorta must pass through the aortic valve.

The aortic valve contains three cusps including the right, posterior and left cusps.

Aortic Valve

Opening to Right Coronary Artery

Opening to Left CoronaryArtery

Aortic Cusp

The right and left cusps of the aortic valve contain sinuses leading to the right and left coronary arteries. The right and left coronary arteries provide oxygenated blood supply to the muscle tissue of the heart.

Right Coronary Artery The coronary arteries provide blood supply to the heart muscle. In particular, the right coronary artery provides blood supply to the right side of the heart which includes the right atrium and right ventricle.The right coronary artery branches into three main branches: the Sinoatrial(SA) nodal branch, the Right Marginal Branch, and the Posterior Interventricular Branch.

Right CoronaryArtery

Right Marginal Branch

PosteriorInterventricular Branch

Anterior View

Posterior View

Left Coronary Artery

The left coronary artery provides blood supply to the left side of the heart, which includes the left atrium, the left ventricle and the muscular septum between the ventricles. The left coronary artery branches into two main branches: the Anterior Interventricular Branch and the Circumflex branch.

Left Coronary Artery

Anterior InterventricularBranch

Circumflex Branch

The coronary arteries may gradually become occluded due to the build up of plaque over a period of time. Plaque is composed of deposits of fats, cholesterol, and calcium within the artery’s walls. Atherosclerosis, the build up of plague over a long period of time, often results in coronary artery disease.

Blockage of Coronary Arteries

Plaque inCoronaryArtery