Cardiac conduction system

Question 1

cardiac conduction system

Answer 1

cellular network composed of highly specialised cell populations that generate and conduct electrical activity through the heart

Question 2

cardiac conduction system purpose

Answer 2

critical for synchronised rhythmic myocardial contraction and opening and closing of valves for efficient pumping of blood

Question 3

cardiac conduction system cells

Answer 3

pacemaker cells and conduction fibres

Question 4

pacemaker cells function

Answer 4

spontaneously generate electrical activity

Question 5

pacemaker cells locations (5)

Answer 5

SAN, AVN, Purkinje fibres, atrioventricular ring, pulmonary vein sleeves

Question 6

pacemaker cell characteristics (6)

Answer 6

smaller size, few contractile elements, many mitochondria, abundant gap junctions, ANS innervation, specialised ion channels

Question 7

pacemaker cell ion channels (4)

Answer 7

funny sodium channels, T-type and L-type calcium channels, fewer leaky potassium channels

Question 8

conduction fibre cells function

Answer 8

preferentially conduct electrical activity throughout heart

Question 9

conduction fibre cell characteristics (5)

Answer 9

large size, abundant gap junctions, fewer myofibrils, rich in glycogen, specialised ion channels

Question 10

conduction fibre ion channels (3)

Answer 10

fast sodium channels, L-type calcium channels, leaky potassium channels

Question 11

SAN function

Answer 11

primary pacemaker of the heart

Question 12

SAN location

Answer 12

superior vena cava junction in right atrium, 9/10 inferior to RAA crest, 1/10 extends as horseshoe across crest into inter-atrial groove

Question 13

wandering pacemaker meaning

Answer 13

leading pacemaker sites are not fixed and can vary beat to beat

Question 14

inferior shifts in leading pacemaker site indication

Answer 14

SAN dysfunction

Question 15

AVN conduction axis

Answer 15

direct myocardial conduction pathway linking atrial and ventricular myocardium

Question 16

AVN conduction axis function

Answer 16

conduction delay to allow ventricular filling

Question 17

AVN function

Answer 17

delays impulses coming from the SAN before transmitting them to the His bundle

Question 18

AVN location

Answer 18

inferior part of right atrium, near septal cusp of tricuspid valve

Question 19

compact AV node function

Answer 19

core part of AVN densely packed with cells that significantly slow conduction velocity forming critical delay

Question 20

compact AV node location

Answer 20

base of inter-atrial septum, near coronary sinus opening and septal cusp of tricuspid valve

Question 21

nodal extensions function

Answer 21

contains transitional cells that surround compact AV node, connect surrounding conduction pathways and facilitate gradual slowing of electrical impulse

Question 22

triangle of Koch location

Answer 22

triangular area of right atrial wall containing the AVN

Question 23

triangle of Koch boundaries

Answer 23

tendon of todaro, tricuspid valve annulus, coronary sinus orifice

Question 24

tendon of todaro

Answer 24

fibrous structure extending from eustachian valve of inferior vena cava toward central fibrous body (posterior boundary of triangle)

Question 25

tricuspid valve annulus

Answer 25

insertion of septal cusp of tricuspid valve (anterior boundary of triangle)

Question 26

coronary sinus orifice

Answer 26

opening of coronary sinus into right atrium (inferior boundary of triangle)

Question 27

His bundle function

Answer 27

transmits electrical impulse from AVN to ventricles via left and right bundle branches