Circulatory system - The heart Flashcards
What does the circulatory system do ?
carry food, oxygen to every cell in the body. and also carry waste products to where they can be removed from the body.
What is the circulatory system made up of ?
heart, blood vessels and blood. Humans have a double circulatory system - two circuits joined together
First and second ventricle
- 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 around all the other organs of the body. The blood gives up it’s oxygen at the body cells and the deoxygenated blood returns to the heart to be pumped out to the lungs again
What is the heart ?
a pumping organ that keeps the blood flowing around the body. The walls of the heart are mostly made of muscle tissue.
What does the heart have ?
Valves to make sure blood flows in the right direction - they prevent it flowing backwards
This is how the heart uses its 4 chambers to pump blood around
1) Blood flows into the two atria from the the vena cava and the pulmonary vein
2) The atria contract, pushing the blood into the ventricles
3) The ventricles contract , forcing the blood into the pulmonary artery and the aorta and out of the heart
4) The blood ten flows to the organs through arteries, and returns through veins
5) The atria fill again and the whole cycle starts over
How does the heart get all the oxygenated blood it needs ?
The heart needs its own supply of oxygenated blood. Arteries called coronary arteries branch off the aorta and surround the heart, making sure that it gets all the oxygenated blood it needs .
What is the resting heart controlled by ?
a group of cells in the right atrium wall that act as a pace maker. These cells produce a small electric impulse, which spread to the surrounding muscle cells, causing them to contract
Why are artificial pacemakers often used ?
control heartbeat if the natural pacemaker cells don’t work properly ( irregular heartbeat ). It’s a little device that’s implanted under the skin and has a wire going to the heart. It produces an electric current to keep the heart beating regularly.
