The heart Flashcards
The heart acts like 2 separate pumps, what do they do?
The right side sends blood to the lungs and the left side pumps blood around the rest of the body
Where does blood always flow from?
A region of higher pressure to a region of lower pressure
What do valves do in the heart?
Prevent the blood from flowing backwards
Is there energy required to make the valves work?
No
What makes valves open and close?
The blood pressing on the valves
What is the cardiac cycle?
The sequence of events that occurs during 1 heartbeat
- Where does the blood flow?
Into the 2 atria (the top chambers)
- What do the atria do?
Contract to push the blood into the ventricles (the lower chambers)
- What do the ventricles do?
Contract, forcing blood into the aorta and pulmonary artery
- Where does the blood go?
The blood flows down the arteries and leaves the heart. The whole cycle starts again
What is more powerful - ventricles or atria?
Ventricles
What happens when ventricles contract?
The heart valves pop shut automatically to prevent backflow into the atria
Why are the ventricle walls thicker?
They need to push the blood further (e.g the left ventricle has to push blood all the way round the body)
What happens as soon as the ventricles relax and why?
The valves at the top of the heart pop shut to prevent backflow of blood (back into the ventricles) as the blood in the arteries is now under a fair bit of pressure
What do most muscles require to make them contract?
Require nerve impulses from the central nervous system
Does the heart produce its own electrical impulses?
Yes
Does the heart have its own pacemaker?
Yes
What sends out regular impulses?
A group of specialised cells called the sino-atrial node in the wall of the right atrium
What do the regular impulses do?
Spread across the atria - making them contract
What do arteries supply the heart muscle with?
Blood
What does heart muscle, like all tissue need and why?
Oxygen and glucose so it can respire and release energy that it needs to function
How many things does the heart get from the blood?
3 things
The heart muscle is supplied with blood from what?
By the coronary arteries
Where do the 2 main coronary arteries come off from?
Come off the aorta
Are the coronary arteries quite thin? (Especially compared to what)
Yes (especially compared to the aorta)
