Chapter 28-29- The Heart and Blood Vessels

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What are the 3 steps of the cardiac cycle?
- 1. Atrial diastole ~blood flows in (Relaxation)
- 2. Atrial systole ~pumped up (Contraction)
- 3. Ventricular systole ~pumped out (Contraction)
What is atrial diastole and where does it take place?

Atrial diastole- blood flows in the atrium. Relaxation
What is atrial systole and where does it take place?

Atrial systole- blood is pumped from atria to ventricles by electrical impulses from the S.A node. (Contraction)
What is the ventricular systole and where does it take place?

Ventricular systole-blood is pumped out of heart. Contraction.
What is the description of step1: atrial diastole?
- Blood enters the heart
- The atria and ventricles are both relaxed (diastole)
- Blood enters the atria
- All valves are closed
What is the description of step2: atrial systole?
- Blood is pumped from atria to ventricles
- Electrical impulses from pacemaker cause the atria to contract (systole)
- This pumps blood to the ventricles
- The tricuspid and bicuspid valves open
- The vanae cavae and pulmonary veins close to stop blood entering the atria
- The semilunar valves remain closed.
What is the description of step3: ventricular systole?
- Blood leaves the heart:
- The atria relax and impulses from the A.V node cause the ventricles to contract (systole).
- This forces blood out out of the heart into the pulmonary artery and the aorta.
- The pressure forces open the semilunar valves and closes the bicuspid and tricuspid valves (-making the ‘lub’ sound).
In which step of the cardiac cycle are both atria and ventricles are relaxed?

1. Atrial Diastole
In which step of the cardiac cycle is blood pumped from the atria to ventricles?

2. Atrial systole
What causes the atria to contract in atrial systole?

Electrical impulses from the S.A node.
In which step of the cardiac cycle does the tricuspid and bicuspid valves open?

2. Atrial systole
What do the A.V nodes impulses cause to contract?

Impulses from the A.V nodes cause the ventricles to contract (systole)
Which step of the cardiac cycle forces blood out of the heart?

3. Ventricular systole
How often does the cardiac cycle repeat?

About 70 times per minute for an adult at rest.
How is the ‘dub’ sound caused?

The ‘dub’ sound is caused by the closure of the semilunar valves (-preventing back flow of blood into ventricles).
How are the heart sounds (‘lub-dub’) caused?

Caused by the closing of the valves phonetically.
What does the ‘lub’ sound like?

‘Lub’ ~ low pitched, quieter, long-lasting sound.
What does the ‘dub’ sound like?

‘Dub’ ~ higher-pitched, louder, shorter sound.
What is a heart murmur?

Any abnormal sound associated with the heart, may indicate damage to one or more of the valves.
What supplies the heart with nutrients and oxygen?

Coronary arteries.

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Chapter 28-29- The Heart and Blood Vessels

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2021-04-22T16:29:14Z