Clin Lab - Cardiac Phys + Electrical fields & vectors

Question 1

What helps maintain a membrane potential at rest?

Answer 1

Na+/K+ pumps

Question 2

Describe Na+ & K+ in relation to inside vs outside the cell

Answer 2

more Na+ outside the cell
more K+ inside the cell

Question 3

Describe how the Na+/K+ pump pumps ions?

Answer 3

3 Na+ outside the cell
2 K+ inside the cell

Question 4

What causes depolarization of cardiac muscle?

Answer 4

opening of Na+ channels

Question 5

What allows for sustained contraction (the plateau)?

Answer 5

opening of K+ channels

Question 6

Where is the refractory period?

Answer 6

this is where we reset everything. Na+/K+ pump works to move N+ back out and K+ back in

nothing can be done during this time.

Question 7

What is the primary pacemaker of the heart? & why?

Answer 7

SA node, b/c it spontaneously depolarizes the fastest

Question 8

EKG machine only picks up activity that is occurring….

Answer 8

outside of the cell

Question 9

If the overall vector points towards a (+) electrode, there is ____ deflection of the EKG lead tracing

Answer 9

upward

Question 10

If the overall vector points away from a (+) electrode, there is ____ deflection of the EKG lead tracing

Answer 10

downward

Question 11

If the overall vector is perpendicular to the (+) electrode, there is ____ deflection of the EKG lead tracing

Answer 11

biphasic

Question 12

Overall placement of the 10 electrodes

Answer 12

• one on each limb
• six on the chest wall

Question 13

What does the R leg lead do?

Answer 13

serves a a ground - detects background signal that is subtracted out from other leads

Question 14

List all the different standards EKG leads

Answer 14

I-III
aVR
aVL
aVF
V1-V6

Question 15

Limb leads I-III are also known as…

Answer 15

bipolar leads

Question 16

Describe Lead I

Answer 16

left arm (+), right arm (-)
views top of heart

Question 17

Describe Lead II

Answer 17

left leg (+), right arm (-)
physiologic way the heart sits in the chest)

Question 18

Describe Lead III

Answer 18

left leg (+), left arm negative

Question 19

List the augmented leads

Answer 19

aVR - right arm (+)
aVL - left arm (+)
aVF - left food (+)

Question 20

What leads give us the electrical activity in the frontal plane of heart?

Answer 20

Leads I, II, III, aVR, AVL, aVF

Question 21

Where does the vector for Lead I point?

Answer 21

horizontally across the top of the heart

Question 22

Where does the vector for Lead II point?

Answer 22

upwards at the heart from the left hip

Question 23

Where does the vector for Lead III point?

Answer 23

upwards at the heart from the right hip

Question 24

Where does the vector for Lead I point?

Answer 24

looking down at the heart from the left shoulder

Question 25

Where does the vector for aVF point?

Answer 25

straight up at the heart from the feet

Question 26

Where does the vector for aVR point?

Answer 26

looking down at the heart from the right shoulder

Question 27

What are the precordial (chest) leads?

Answer 27

V1-V6

Question 28

What do the chest leads show us?

Answer 28

horizontal plane of the heart

Question 29

Placement of V1/V2

Answer 29

overlays the RV
V1 - right side of the sternum
V2 - left side of the sternum

Question 30

Placement of V3/V4

Answer 30

overlays the septum

V4 - midclavicular line (5th intercostal space)

Question 31

Placement of V5/V6

Answer 31

overlays the LV

angle around was we get to the left armpit area.

Question 32

V1 & V2 are looking at…

Answer 32

RV

Question 33

V3 & V4 are looking at the

Answer 33

septum

Question 34

V5 & V6 are looking at the….

Answer 34

LV