Cardio 2

Question 1

What happens during “lub”?

Answer 1

• Ventricular contraction (depolarization)

- S1

Question 2

What happens during “dub”?

Answer 2

• ventricular filling (repolarization)

- S2

Question 3

S1 =

Answer 3

Tricuspid and mitral valves close

Question 4

S2 =

Answer 4

Aortic and pulmonic valves close

Question 5

What are the rhythms to worry about as a PT?

Answer 5

• normal sinus rhythm
• PVC
• A-fib
• V-fib
• flatline

Question 6

What structures control heart action?

Answer 6

• cardiac action potentials

- conduction system

Question 7

Cardiac action potentials =

Answer 7

Electrical impulses

Question 8

SA node: where is it?

Answer 8

• in RA

- just above tricuspid valve

Question 9

What does the SA node do?

Answer 9

Generates ~75 action potential per minute

Question 10

SA node =

Answer 10

Sinoatrial node

Question 11

AV node =

Answer 11

Atrioventricular node

Question 12

Where is the AV node?

Answer 12

• in RA
• superior to tricuspid valve
• near autonomic parasympathetic ganglia

Question 13

What is the function of the autonomic parasympathetic ganglia?

Answer 13

Slow impulse conduction through the AV node

Question 14

From the AV node, where does an AP go?

Answer 14

• bindle of His (av bundle)
• R and L bundle branches
• Purkinje fibers

Question 15

Conduction sequence:

Normal excitation originates in ______, then propagates through ______

Answer 15

• SA node

- both atria

Question 16

Conduction sequence:

Atrial depolarization spreads to _______, and passes through _______ to the _________

Answer 16

• AV node
• bundle of His
• bundle branches/Purkinje fibers

Question 17

The intrinsic pacemaker rate is (faster/slower) in structures further along the activation pathway

Answer 17

Slower

Question 18

The AV nodal rate is (faster/slower) than the SA node rate

Answer 18

Slower

Question 19

Why is the intrinsic pacemaker rate of the AV node slower than the SA node?

Answer 19

prevents AV node from generating a spontaneous rhythm under normal conditions

Question 20

AV node rate

Answer 20

Refractory

Under 55 bpm

Question 21

What happens if the SA node becomes inactive?

Answer 21

AV nodal rate determines ventricular rate

Question 22

Conduction sequence (structures)

Answer 22

1. SA node
2. Atrial myocardium
3. AV node
4. Bundle of His
5. Bundle branches
6. Purkinje fibers
7. Ventricular myocardium

Question 23

What is resting membrane potential?

Answer 23

Voltage differential across the cell membrane

Question 24

Depolarization =

Answer 24

• electrical activation of the cell

- inside the cell is less negatively charged

Question 25

Drugs and depolarization

Answer 25

Drugs that alter ion movement can affect HR

Question 26

repolarizatoin =

Answer 26

• electrical deactivation

- inside the cell is more negatively charged

Question 27

Hyperpolarization =

Answer 27

• too much extracellular K+

- resting potential is more negative

Question 28

Refractory period =

Answer 28

• no new cardiac AP can be initiated

- gives time for channels that permit Na+ and Ca2+ to re-enter the cell

Question 29

What can abn refractory periods do?

Answer 29

Cause dysrhythmias

Due to heart dz

Question 30

Electrocardiogram =

Answer 30

Sum of all cardiac APs

Question 31

Automaticity =

Answer 31

generating spontaneous depolarization to threshold so that SA and AV nodes generate cardiac APs without any stimulus

Question 32

Rhythmicity =

Answer 32

• SA sets the pace bc it’s usually the fastest (60-100 bpm)

- AV (40-60 bpm) takes over if SA damaged

Question 33

What takes over for the AV node?

Answer 33

Conduction cells in the atria

Question 34

These can also conduct potential (30-40 bpm)

Answer 34

Purkinje fibers