Anatomy & Physiology of the Heart

Question 1

1 points to the…

Answer 1

SA node

Question 2

2 points to the…?

What are the fibers between 1 &2 called?

Answer 2

AV node

Internodal tracts

Question 3

3

Answer 3

Bundle of His

Question 4

6

Answer 4

Right and Left Bundle Branches

Question 5

5

Answer 5

Purkinje fibers

Question 6

Name the bundle that runs from the SA node to the left atrium.

Answer 6

Bachmann’s Bundle

Question 7

The left bundle branch splits into two main tracts called…

Answer 7

Left, anterior fascicle & posterior fascicle

Question 8

The fine conduction network that spreads the electrical signal throughout the ventricles is called…

Answer 8

the Purkinje network

Question 9

What is an ectopic beat?

Answer 9

Any cardiac pulsu originating outside the SA node

Question 10

List the three mechanisms responsible for ectopic beats

Answer 10

Altered automaticity

Triggered Activity

Re-entry

Question 11

Define Re-entry

Answer 11

A mechanism responsible for ectopic beats where an impulse travels through an area of myocardium, depolarizes, then reenters the same area to depolarize again. Reentry requires circular movement of the impulse that continues as long as it encounters receptive cells

Question 12

Define triggered activity

Answer 12

Abnormal electrical impulses that occur during repolarization when cells are normaly quiet. Ectopic pacemaker cells may depolarize more than once after stimulation by a single electrical impulse and result in atrial, junctional, or ventricular beats occuring singly, in pars, runs (of 3 or more) or a sustained ectopic rhythm

Question 13

Define altered automaticity

Answer 13

Ectopic pacemaker takes over because it usurps control from the SA node by either accelerating its own automaticity or because the SA node decreases its own automaticity

Question 14

What is depolarization?

Answer 14

• Depolarization = cells losing their internal negativity/becoming more positive inside
• Depolarization is the fundamental electrical event of the heart

Question 15

How does depolarization occur?

Answer 15

• Cells are normally have internal negative charge in relation to outside of cell
• Depolarization is initated by arrival of an electrical impulse that causes positively charged ions to cross the cell membrane into the cell
• With each spontaneous depolarization, a new action potential is generated, which stimulates neighboring cells to depolarize and so on
• This creates a wave of electricity that can be transmitted through the entire heart

Question 16

What is repolarization?

Answer 16

• The process of cardiac cells restoring their resting polarity
• Cell membrane pumps reverse the flow of ions to return cell to be more negative inside than outside
• Repolarization is necessary to enable cells to fire again

Question 17

What determines the rate of depolarization through an optimally functioning heart?

Answer 17

• Pacemaker cells can spontaneously depolarize over and over and do so at a typical rate
  
  • SA Node: 60-100x/min, usually sets the rate
• The rate is also determined by autonomic nervous system input and/or demands of body for increased cardiac output