Chapter 11: Conduction System of the Heart

Question 1

What initiates the electrical activity of the heat?

Answer 1

specialized muscle cells

Question 2

wave of electrical activity

Answer 2

action potential

Question 3

Where do impulses initiate?

Answer 3

SA (sinoatrial) node

Question 4

What is the natural pacemaker of the heart?

Answer 4

SA node

Question 5

Where is the SA node located?

Answer 5

In the R atrium, near the opening of the superior vena cava

Question 6

True or false: Ability of the cardiac muscle to depolarize and contract depends on the nervous system.

Answer 6

False; it is intrinsic

Question 7

What is the path of conduction through the heart?

Answer 7

SA node -> AV node -> AV bundle (bundle of His) -> R and L branches -> Purkinje fibers -> muscle fibers contract.

Question 8

On average, how often does atrial systole occur?

Answer 8

every .85 seconds

Question 9

What is one heartbeat comprised of?

Answer 9

1) Atrial systole
2) Ventricular systole
3) Diastole (heart relaxes)

Question 10

How many heartbeats comprise one cardiac cycle?

Answer 10

1 heartbeat

Question 11

What happens is the SA node is not working properly?

Answer 11

AV node takes over (slower HR: 40-60 bpm)

Question 12

What happens if both the SA and AV nodes stop working?

Answer 12

Bundle of His takes over (30-40 bpm)

Question 13

What does lack of a P wave indicate?

Answer 13

Atrial fibrillation

Question 14

What does an elevated ST segment in an EKG represent?

Answer 14

STEMI