The heart

Left and right atria

Left and right atria

• top 2 chambers of the heart.

• pump blood into ventricles.

Left and right ventricle

• bottom two chambers of the heart.

• pump blood to either the lungs or whole body.

Pulmonary circuit

right side of heart pumps blood to the lungs.

Systemic circuit

left side pumps blood to rest of the body.

The heart is myogenic…

it generates its own muscle contractions.

Why is the left hand side of the heart thicker and more muscular?

generates more pressure to push blood around the systemic circuit.

Why is the right hand side of the heart less muscular?

needs to be at a lower pressure, so doesn’t damage the alveoli as blood arrives at the lungs.

Right atrium

receives deoxygenated blood from the body (via the vena cava.)

Right ventricle

carries deoxygenated blood to the lungs (via the pulmonary artery.)

Left atrium

receives oxygenated blood from the lungs (through the pulmonary vein.)

Left ventricle

pumps oxygen to rest of the body (via the aorta.)

Valves

prevent the backflow of blood

How does heart rate change during exercise?

1. muscles need more energy (oxygen) to respire more.

2. exercise increases the amount of carbon dioxide in the blood.

3. this causes the heart to contract more frequently and with more force.

How does heart rate change with adrenaline?

1. adrenaline released from glands.

2. adrenaline binds to receptors in the heart.

3. cardiac muscle contracts more frequently and with more force. Blood flow increases and heart pumps more blood.

4. Increases oxygen supply to muscle tissue, enabling someone to run away or fight.

Arteries

• carry blood away from the heart.

• carries blood under high pressure.

Adaptations of arteries

1. elastic fibers allow arteries to expand.

2. thick walls, which makes them strong.

Capillaries

Carry blood really close to every cell for the body to exchange substances with them.

Adaptations of capillaries

1. one cell thick. this increases rate of diffusion by decreasing the distance over which it happens.

2. permeable walls. substances can diffuse in and out.

Veins

• take blood back to the heart.

• blood is at a lower pressure.

Coronary Heart Disease

• Coronary Arteries, that supply blood to the muscle of the heart, become blocked by layers of fatty substances.

• Causes arteries to become narrow, so blood flow is restricted.

• Results in a heart attack.

Causes of Coronary Heart Disease

• Diet high in saturated fat

• Smoking

• Inactive lifestyle - leads to high blood pressure which damages the lining of the arteries.