Circulartory System- The heart

Question 1

why is the human circulatory system known as the double circulatory system?

Answer 1

it is made up of two circuits joined together:
•in the first one the right ventricle pumps deoxygenated blood to the lungs to take in oxygen. The blood then returns to the heart
•in the second one the left ventricle pumps oxygenated blood all around the other organs of the body. The blood gives up its oxygen at the body cells and the deoxygenated blood returns to the heart to be pumped to the lungs again

Question 2

what is the heart?

Answer 2

a pumping organ that keeps blood flowing around the body

Question 3

what are the walls of the heart made up from?

Answer 3

muscle tissue

Question 4

why does the heart have valves?

Answer 4

to prevent back flow of blood

Question 5

how does the heart pump blood around the body?

Answer 5

1)Blood flows into the the atria from the
vena cava and the pulmonary vein.
2) The atria contract, pushing the blood into ventricles
3) The ventricles contract, forcing the blood into the pulmonary artery and the aorta, and out of the heart.
4) The blood then flows to the organs through
arteries, and returns through veins
5) The atria fill again and the whole cycle starts over.

Question 6

what is the role of coronary arteries?

Answer 6

they ensure the heart gets all the oxygenated blood it needs

Question 7

what are pacemaker cells?

Answer 7

•a group of cells in the right atrium that control your resting heartbeat
•they produce a small electric impulse which spreads to the surrounding muscle cells causing them to contract

Question 8

when is an artificial pacemakers used?

Answer 8

they are used to control natural heartbeat when the natural pacemaker cells don’t work properly e.g. when a patient has an irregular heartbeat

Question 9

how does an artificial pacemaker work?

Answer 9

•it is a little device that is implanted under the skin with a wire going to the heart
•it produces an electric current to keep the heart beating regularly