CABS Electrical Conduction and ECG

Question 1

What is the role of pacemaker cells?

Answer 1

Electrical conduction point (SA node)

Question 2

What is the role of electrical conduction cells?

Answer 2

wiring of the heart

Question 3

What is the role of the myocardial cell?

Answer 3

contracting, muscular cells that contain actin and myosin (more specialized than skeletal muscle cells)

Question 4

What is the normal pace range of the sinoartial node?

Answer 4

60-100bmp

Question 5

What is the normal pace range of the atrioventricular node?

Answer 5

40-60bmp

Question 6

What is the normal pace range of the bundle of his?

Answer 6

20-40bpm

Question 7

What is the normal pace range of the bundle branches?

Answer 7

20-40bpm

Question 8

What is the normal pace range of the Purkinje fibers?

Answer 8

20-40bpm

Question 9

Cardiac cells include

Answer 9

Pacemaker cells which generate conduction

Electrical conducting cells which send along the signal

Myocardial cells which actually contract

Question 10

Normal sinus rhythm arises from stimulation of what

Answer 10

Sinoarterial node (pace maker of sinus rhythm)

Question 11

The sinoarterial node receives blood supply from what artery?

Answer 11

Sinoarterial nodal artery

Question 12

What structure stimulates the left atria to contract?

Answer 12

Bachman’s bundle

Question 13

Where does sinus rhythm originate?

Answer 13

SA node

Question 14

What structure acts as an electrical insulator between the atria and ventricles?

Answer 14

Fibrous Skeleton

Question 15

The atrioventricular node allows for a pause before the electrical conduction is passed along to the Bundle of His and Purkinje Fibers, how long is the pause?

Answer 15

0.1 seconds

Question 16

What does the pause created by the atrioventricular node allow for?

Answer 16

Blood from the atria to fill the ventricles

Question 17

Should the QRS be wide or narrow?

Answer 17

Narrow, widening means there is something wrong with the ventricles

Question 18

What is R-prime?

Answer 18

2nd upward deflection after QRS complex

Question 19

What is always an irregularly irregular rhythm?

Answer 19

aFib

Question 20

What is resting membrane potential?

Answer 20

Difference in electrical charge across cellular membrane. Transmembrane potential for cardiac myocytes is -90mV

Question 21

What is the action potential?

Answer 21

Rapid shift of cellular voltage

Question 22

Unlike in skeletal muscles where the trigger will be coming from acetylcholine, in cardiac muscle cells the trigger to contract comes from?

Answer 22

Automaticity from the SA node

Question 23

Positive inotropes help with

Answer 23

increasing muscular contraction

Question 24

Positive chronotropes help with

Answer 24

increasing HR (sympathetic- norepinephrine)

Question 25

Negative chronotropes help with

Answer 25

decreasing HR (parasympathetic - acetylcholine)

Question 26

Beta receptor that increases HR and increases contractility

Answer 26

B1

Question 27

Beta receptor that inhibits smooth muscle contraction

Answer 27

B2

Question 28

Alpha receptor that increases smooth muscle contraction which leads to increased BP

Answer 28

A1

Question 29

Alpha receptor that inhibits secretions

Answer 29

A2

Question 30

What is the potassium level in normokalemia

Answer 30

K 3.5 - 5.0 mM

Question 31

What is the potassium level range in moderate hyperkalemia

Answer 31

K < 8 mM

Question 32

What is the potassium level of severe hyperkalemia

Answer 32

K > 8 mM

Question 33

What electrolyte travels with potassium?

Answer 33

Magnesium