Section 6 - The Heart Flashcards
Which side of the heart sends blood to the lungs?
The right side
Which side of the heart pumps blood around the rest of the body?
The left side
Blood always flows from a region of _______ pressure to a region of ________ pressure.
higher, lower
What in the heart prevents the blood from flowing backwards?
Valves
What is required for the valves to work?
No energy! It’s the blood pressing on the valves that makes them open and close
What is the cardiac cycle?
The sequence of events that occurs during one heartbeat
Describe the events of the cardiac cycle (4)
1) Blood flows into the two atria (the top chambers).
2) The atria contract to push the blood into the ventricles (the lower chambers).
3) The ventricles contract, forcing blood into the aorta and pulmonary artery.
4) The blood flows down the arteries and leaves the heart. The whole cycle starts again.
Are the atria or ventricles more powerful?
Ventricles
What happens to the heart valves when the ventricles contract?
They pop shut automatically to prevent backflow into the atria
Why are the ventricle walls thicker?
They need to push the blood further
What happens to the heart valves at the top of the heart as soon as the ventricles relax?
They pop shut to prevent backflow of blood (back into the ventricles)
What do most muscles require to make them contract?
Nerve impulses from the central nervous system
The heart produces its own __________ impulses
electrical
What is the sino-atrial node?
A group of specialised cells called the sino-atrial node, in the wall of the right atrium that sends out regular impulses. These spread across the atria, making them contract.
Which 2 things does heart tissue need so it can respire and release the energy it needs to function?
Oxygen and glucose
