Cardiac rhymth and electrocadiography L9

Question 1

2 types of cardiac cells

Answer 1

myocardial cells

conduction cells

Question 2

what are myocardial cells for

Answer 2

generating pumping pressure to pump blood around the body

Question 3

what are conduction cells for

Answer 3

rapidly spreading electrical signals to the myocardial cells

Question 4

audtorhythmicity=

Answer 4

pacemaker cells can generate their own rhythm of action potentials that triggers contraction

Question 5

what is the slow automatic depolarisation of pacemaker cells called

Answer 5

pacemaker potential

Question 6

what does pace maker potential determine

Answer 6

rate of firing SAN

Question 7

what is the intrinsic rate of SAN

Answer 7

70bpm

110-120bpm without vagus nerve

Question 8

intrinsic rate of AVN=

Answer 8

50bpm

Question 9

purkinje fibres rate of firing=

Answer 9

30-40bpm

Question 10

What are SAN and AVN innervated by

Answer 10

both parasympathetic and sympathetic

Question 11

what is the heart not SAN/AVA innervated by

Answer 11

poorly by the parasympathetic

Question 12

what does adrenaline act on

Answer 12

beta 1 receptors

Question 13

what effect does adrenaline have on SAN

Answer 13

positive chronotropic effect

Question 14

what effect does adrenaline have on AVN

Answer 14

increase automaticity

Question 15

effect of adrenaline on ventricular muscles

Answer 15

increase both automaticity and force

Question 16

2 beta blocker s

Answer 16

propanolol

atenolol

Question 17

ECG=

Answer 17

electrocardiogram

Question 18

what is an ECG

Answer 18

recording electrical activity of the heart

Question 19

pattern of ECG=

Answer 19

P-QRS-T

Question 20

P =

Answer 20

atrial depolarisation

Question 21

QRS=

Answer 21

ventricle depolarisation

Question 22

T=

Answer 22

ventricular repolarisation

Question 23

Q=

Answer 23

inter-ventricular septum

Question 24

R=

Answer 24

the apex and free walls

Question 25

S=

Answer 25

regions near the base

Question 26

bradycardia=

Answer 26

<60bpm

Question 27

tachycardia=

Answer 27

> 100bpm

Question 28

what is the commonest arrhythmia

Answer 28

atrial fibrillation (AF)

Question 29

treatment of AF

Answer 29

beta blockers
anticoagulants
(used to be digoxin)

Question 30

what does digoxin do

Answer 30

blocks sodium-potassium ATPase

causes calcium build up greater force of contraction

Question 31

what is AF caused by

Answer 31

multiple re-entrant circuits sweeping around atrial myocardium (that occasionally hit SA node)

Question 32

what type of drug is digoxin

Answer 32

cardiac glycoside