The Structure of The Heart

The Heart• Muscular pump, about the size of a clenched

fist– Made up of a special muscle called

Myocardium• This can contract continuously without getting

tired

• Main purpose is to drive blood through the arteries– This delivers blood to the working muscles and

other tissues.

Task…Find a picture of a blank heart (that is suitable to annotate) and upload it to a blank document.

- Then do some light background research on the different labels of the heart including…

- Structure of the cardiovascular system- heart:

Atria

Ventricles

Bicuspid valve and tricuspid valve

Aortic valve and pulmonary valve

Aorta and vena cava – superior and inferior

Pulmonary vein and pulmonary artery

The Heart continued• The Heart sits in a twin

layered sac known as the Pericardium – Filled with pericardial

fluid• Prevents friction as

your heart beats.

The Heart continued• The heart wall has 3 layers

– Epicardium (Outer)

– MYOCARDIUM (middle layer and most of the heart wall)

– Endocardium (The inner layer)

AtriaUpper chambers of the heartReceive blood.

Right Atrium – receives deoxygenated blood from the body (Via the Vena Cava)

Left Atrium – receives oxygenated blood from the lungs (Via the pulmonary Vein)

• Ventricles– Lower chambers of the heart– They have thicker walls and are

stronger– Job is to pump the blood

– Right Ventricle pumps blood to the lungs (pulmonary circulation)

– Left ventricle pumps blood to the body (systemic circulation)

Valves• Tricuspid Valve

• Bicuspid Valve– Also known as the mitral valve

• Aortic Valve

• Pulmonary Valve– All valves make sure that the blood

flows in one direction, and there is no back flow

• Chordae Tendineae– Cord like tendons that connect to the

tricuspid and bicuspid valves• Ensure the valves stay the right way

round and keep the blood flowing in the same direction.

Aorta and Vena Cava• The largest

Artery is the Aorta– Carries

oxygenated blood directly out of the heart to the body tissues

• The largest vein is the Vena Cava– Carries blood directly

into the heart from the body

– Superior vena cava– brings blood from the

upper body– Inferior Vena Cava

– Brings blood from the lower body.

Pulmonary Circulation• Pulmonary Artery– Carries

deoxygenated blood from the heart to the lungs. • It is the only artery

that carries deoxygenated blood

• Pulmonary Vein– Carries oxygenated

blood from the lungs to the heart• It is the only vein

that carries oxygenated blood.

The Heart = Double pump• To describe the flow of blood

around the heart and the body, you will need to mention that the heart is made up of two pumps– Pulmonary circulation• Pumps blood to and from the

lungs

– Systemic circulation• Pumps blood around the body

Passage of blood flowBlood flows into and out of the

heart and around the body in one direction.

The heart is split into two distinct pumps by the Septum. This makes sure that the

oxygenated and deoxygenated blood don’t mix.

When describing the passage of blood flow around the heart, it is best to use a diagram and start on the right side of the heart.

The RIGHT side of the heart

The right ventricle contracts and the blood is pushed out of the heart through the semi lunar or pulmonary valve and into the pulmonary artery

The pulmonary artery carries the blood to the lungs

The heart relaxes and the valves close to stop back flow of the blood

In the lungs, the blood becomes oxygenated, and begins it’s journey back to the heart.

• Blood enters the heart (when it is relaxed) via the vena cavae,• It goes into the right atrium• The right atrium contracts and the blood goes through the tricuspid valve and

into the right ventricle

The LEFT side of the heart• The heart is relaxed, and this

allows blood to enter the left side of the heart from the pulmonary vein

• It enters the left atrium

• The left atrium contracts and pushes blood through the bicuspid valve and into the left ventricle

• The left ventricle has a very strong muscular wall and contracts very strongly. This closes the bicuspid valve to prevent backflow, and pushes the blood through the aortic valve and into the aorta. This is the largest artery and splits taking the blood to different areas of the body

• The heart contracts and the aortic valve closes, preventing back flow of the blood.

Terminology• Heart rate (H.R.)– The amount of times the heart beats in a minute. • Usually measured in beats per minute (b.p.m.)

• Stroke Volume (S.V.)– The amount of blood leaving the left ventricle in one

beat. • Normally measure in mililitres

• Cardiac Output– The amount of blood leaving the heart in one minute• Normally measured in litres/minute

• Cardiac Output = Stroke Volume x Heart Rate

Task…Finish off annotating and labelling the various

parts of the heart: