Heart EKG

Question 1

What does a P-wave represent?

Answer 1

Atrial depolarization and beginning of contraction of both atria

Question 2

What does the term depolarization mean?

Answer 2

Changing myocyte cells from negative to positive

Question 3

Where does depolarization begin?

Answer 3

Right atrium

Specifically SA node

Question 4

What is the purpose of depolarization?

Answer 4

To force muscle cells to contract

Question 5

What causes myocardial contraction?

Answer 5

Depolarization

Question 6

What is the recovery phase after depolarization?

Answer 6

Repolarization

Question 7

Describe automaticity

Answer 7

The generation of peacemaking stimuli

Question 8

What ionic movement begins depolarization in the right atrium?

Answer 8

Movement of Na+ ions

Question 9

How do the mitral and tricuspid valves act between the atria and ventricles in the conduction system?

Answer 9

Electrically insulate ventricles from atria

Question 10

The ___ node is the only electrical conduction pathway between the atria and ventricles.

Answer 10

AV node.

Question 11

When does depolarization slow?

Answer 11

Within the AV node, allowing blood to pass through AV valves into the ventricles

Question 12

Why does depolarization slow down through the AV node?

Answer 12

Carried by Ca++ ions

Question 13

Where does ventricular conduction begin and then continue?

I.e. what fibers

Answer 13

His bundle to the right and left bundle branches

Question 14

What are the His bundle, right and left bundles made of?

Answer 14

Purkinje fibers

Question 15

What is the QRS complex?

Answer 15

Depolarization of the ventricular myocardium

Question 16

What ions move through the ventricular for depolarization down the conduction system?

Answer 16

Na+ ions

Question 17

How does the electrical conduction system spread out through the ventricular cavities?
(I.e. in to out or out to in?)

Answer 17

Endocardium to epicardium

Question 18

What is the T-wave?

Answer 18

Rapid phase of ventricular repolarization

Question 19

What is repolarization? (I.e. what ions are involved?)

Answer 19

K+ ions leave myocytes

Question 20

When does ventricular contraction (systole) begin?

Answer 20

QRS complex, continues to end of T-wave

Question 21

Describe the Q-T interval

Answer 21

Good indicator of repolarization, corrected for rate (as QT intervals depend on heart rate)

Question 22

Describe P=R interval

Answer 22

Time between atrial depolarization to ventricular depolarization

Question 23

Describe the S-T segment

Answer 23

Initial period of ventricular repolarization, although minimal

Question 24

What is the S wave?

Answer 24

A few small areas of the ventricles that are activated at a late stage

Question 25

What do Ca++ ions cause?

Answer 25

Myocyte contraction?

Question 26

What do Na+ ion movements do?

Answer 26

Produce cell-to-cell conduction of depolarization, except in AV node which is dependent on Ca++ ions

Question 27

In what order does the ventricular muscle repolarization? (I.e. out to in or in to out)

Answer 27

Epicardium to endocardium

Question 28

What is the P-R interval

Answer 28

Signifies time it takes impulse to pass from atria to ventricles

Question 29

Describe Starling’s Law of the heart

Answer 29

Intrinsic mechanisms in cardiac muscle ensure cardiac output = cardiac input from circulation within normal minutes (5 L/min) Greater input causes greater stretch of muscle, which increases force of contraction and allows for greater amount of blood to be ejected

Question 30

What happens if patient loses myocardial cells (i.e. in myocardial infarction)? (In relation to Starling’s Law)

Answer 30

Part of heart wall not -articulating in electrical conduction, so line will move towards cardiac failure

Question 31

What happens during diastole?

Answer 31

Atrial pressure becomes > ventricular pressure | AV valves open filling ventricles

Question 32

What happens during systole?

Answer 32

Ventricle pressure > atrial pressure AV valves close Aortic valve opens Blood flows out to aorta and through lungs w/o backing into atria

Question 33

What causes the first lub sound of the heart?

Answer 33

Closing of the mitral and tricuspid valves

Question 34

What causes the second lub sound of the heart?

Answer 34

Closing of the pulmonary and aortic valves

Question 35

Where is the SA node located?

Answer 35

Opening of the superior vena cava into the right atrium

Question 36

Where it’s he AV node located?

Answer 36

Junction f the coronary sinus and right atrium upon the right fibrous trigone