4.2.2.2 The heart and blood vessels

What does the circulatory system do?

Carry oxygen and nutrients to every cell in the body and removes the waste products

How does the heart pump blood around the body in a double circulatory system?

Deoxygenated blood flows into the right atrium and then into the right ventricle which pumps it to the lungs for gas exchange. Oxygenated blood flows into the left atrium and then into the left ventricle which pumps oxygenated blood around the body

What do coronary arteries do?

Cover the heart to provide its own oxygenated blood supply

What is the process of blood flow through the heart?

Blood flows into the right atrium through the vena cava and left atrium through the pulmonary vein. The atria contract, forcing the blood into the ventricles. The ventricles the contract, pushing the blood from the right ventricle into the pulmonary artery to be taken into the lungs, and blood in the left ventricle to the the aorta to be taken around the body

What do valves do?

Prevent the backflow of blood

Where is a pacemaker found?

In the right atrium

What is a pacemaker?

A group of cells which provide stimulation through small electrical impulses which pass as a wave across the heart muscle, causing it to contract

What is an artificial pacemaker?

An electrical device that produces a signal causing the heart to beat at a normal speed if the individual has an irregular heartbeat

What are the three different types of blood vessels in the body?

Arteries, veins, capillaries

What do arteries do?

Carry blood away from the heart

How are arteries adapted to do their role?

Layers of muscle in the walls make them strong and elastic fibres allow them to stretch, which helps the vessels withstand the high pressure created by the pumping of the heart

What do veins do?

Carry blood towards the heart

How are veins adapted to do their roles?

The lumen is wide to allow the low pressure blood to flow through and they have valves to ensure the blood flows in the right direction

What do capillaries do?

Allow the blood to flow very close to cells to enable substances to move between them

How are capillaries adapted to do their role?

They have one cell thick walls which create a short diffusion pathway and permeable walls so substances can move across them

How can you calculate the rate of blood flow?

Volume of blood/number of minutes