Cardiac cycle

Question 1

What are the structures involved in cardiac electrical conduction?

Answer 1

Sino Arterial Node, Atrioventricular Node, Atrioventricular Bundle (Bundle of His), Bundle Branches Left & Right, Purkunje Fibres.

Question 2

Describe the sequence of electrical conduction through the heart

Answer 2

Sino node causes atrial muscle to contract. The signal travels to the atrioventricular node, through the bundle of his, down the left and right branches and through the purkunje fibres.

Question 3

Describe the properties of cardiac muscle which allow it to beat effectively

Answer 3

Have short, fat branched fibres which connect to junctions called intercalated disks that contain gap junctions which allow electrical impulses through the heart.

Question 4

Describe the relationship between the electrical and mechanical activity of the heart

Answer 4

The heart has pacemaker cells that create an electrical sequence of depolarization and repolarization causing the heart to move. Together forming a relationship of electrical and mechanical activity.

Question 5

State the ranges for a normal heart rate

Answer 5

About 75 beats per minute.

Question 6

Define systole of the atria

Answer 6

Contraction of atria, AV valves open and blood is forced into ventricles

Question 7

Define diastole of the atria

Answer 7

Relaxation of atria, AV valves close and atria fills with blood

Question 8

Define systole of the ventricles

Answer 8

Contraction of ventricles, semilunar valves open pushing blood into pulmonary artery and aorta

Question 9

Define diastole of the ventricles

Answer 9

Relaxation of ventricles, semilunar valves and AV valves are closed