LECTURE 9: the excitable heart

Question 1

what is the pacemaker of the heart

Answer 1

Sino atrial node

Question 2

electrical excitation of heart is drive by activity of…

Answer 2

SA node

Question 3

where is SA node located

Answer 3

towards the top right of the right atrium

Question 4

where is cardiac action potential initiated

Answer 4

SA node

Question 5

path of cardiac action potential

Answer 5

Starts at SA node, spreads through both atria through the intranodal bundles, then slowed down at AV node before spreading down AV bundle splitting into left and right bundle branches, finally heading through walls of ventricle through purkinje fibres, when in ventricular myocytes it spreads rapidly through muscle cells through electrical couplings called gap junctions

Question 6

AV node

Answer 6

atrioventricular node

Question 7

gap junctions

Answer 7

Pores with low resistance to
ionic current

Allow current flow between
adjacent cells

Question 8

what does atrial bundle connect together

Answer 8

SA node to left atrium

Question 9

what is normal range for resting heart rate

Answer 9

40-100

Question 10

what part of autonomic nervous system is dominant during rest?

Answer 10

parasympathetic

Question 11

how is parasympathetic system stimulated

Answer 11

signalled by vagous nerve

Question 12

what part of autonomic nervous system is dominant during exercise?

Answer 12

sympathetic

Question 13

what is sympathetic system stimulated by

Answer 13

sympathetic trunk

Question 14

where are AV node and bundles

Answer 14

ventricles, left and right side for the bundles

Question 15

where are purkinje fibres

Answer 15

walls of ventricles

Question 16

what is an ECG

Answer 16

a graphical representation of the electrical activity in the heart

Question 17

P-wave of ECG can be seen at and what does it represent

Answer 17

atrial depolarisation

first wave on ECG

Question 18

first heart sound

Answer 18

lubb

Question 19

second heart sound

Answer 19

dupp