Electrical Properties of the Heart

Question 1

the heart is electrically connected by

Answer 1

gap junctions

Question 2

the heart is physically connected by

Answer 2

desmosomes

Question 3

Gap junctions and desmosomes together make the

Answer 3

intercalated disc

Question 4

excitation contraction coupling is the process whereby an

Answer 4

action potential triggers a myocyte to contract (and then subsequently relax)

Question 5

Cardiac muscle has a …… action potential

Answer 5

long (about 250msec)

Question 6

Cardiac muscles has a long refractory period so it cannot exhibit

Answer 6

tetanic contraction

Question 7

Ca2+ entry from outside the cell can regulate

Answer 7

contraction

Question 8

calcium release does not saturate the troponin 0 so the regulation of Ca2+ release can be used in

Answer 8

varying the strength of contraction

Question 9

Pacemaker potential

Answer 9

the slow, positive increase in cells membrane potential that occurs at the end of the AP til the start of the new AP

(what causes it to reach threshold potential and fire an AP)

Question 10

Ca2+ channel blockers

Answer 10

decrease the force of contraction

Question 11

Cardiac glycosides

Answer 11

increase the force of contraction

Question 12

hyperkalaemia

Answer 12

fibrillation and heart block

Question 13

hypokalaemia

Answer 13

fibrillation and heart block

Question 14

hypercalcaemia

Answer 14

increased HR and force of contraction

Question 15

hypocalcemia

Answer 15

decreased HR and force of contraction

Question 16

Sinoatrial node is the

Answer 16

pacemaker

Question 17

AV node is the

Answer 17

delay box

Question 18

Bundle of his

Answer 18

transmits electrical impulses from AV node to ventricles

Question 19

Lots of small extracellular electrical potentials evoked by many cells depolarising can

Answer 19

summate to create large electrical waves

Question 20

P wave corresponds to

Answer 20

atrial depolarisation

Question 21

QRS complex corresponds to

Answer 21

ventricular depolarisation

Question 22

T wave corresponds to

Answer 22

ventricular repolarisation