w6 cardiac cycle and conduction system

Question 1

cardiac conduction system

Answer 1

electrical impulses are generated within heart through depolarization of cells. the membrane potential of cardiac cells (uneven distribution of charges on the two sides of the membrane) is negative.
depolarization- negative potential changes to positive potential
depolarization- cells return to charge

Question 2

what is charge of heart

Answer 2

-90v negative charge and it is the membrane potential

Question 3

path of electrical impulse

Answer 3

sinoatrial SA node, to atrioventricular node AV and then bundle of his

Question 4

SA node

Answer 4

located in right atrium near superior vena cava. it is known as the pacemaker of the heart 60-100 beats per minute.
when the SA fires an impulse it spreads throughout upper chambers causing atrial contraction

Question 5

AV node

Answer 5

located in low septum of right atrium. it slows impulses between upper and lower chambers this allows the blood in atria that are contracting to travel to ventricles. The impulse then travels to the bundle of his.

Question 6

Bundle of His

Answer 6

muscle fibres pass into two separate bundles the right and the left. The impulses then travel to the distal parts of the bundles called PURKINJE FIBRES – these are in endocardium and myocardium of ventricles
-blood filled ventricles contract -blood to lungs and blood to body.

Question 7

where can electrical impulses pass to ventricles and why?

Answer 7

• the bundle of his and this is because the fibrous skeleton between the atria and ventricles prevents electrical impulses from travelling between them.

Question 8

cardiac cycle

Answer 8

beginning of one heart beat to the beginning of the next.

Question 9

systole

Answer 9

contraction.

Question 10

diastole

Answer 10

relaxation.