L26

Question 1

Dominant pacemaker:

Answer 1

SA node – highest frequency 100/s

Question 2

secondary pacemaker:

Answer 2

AV node – 40-60/2 sponateneous beat

Question 3

tertiary pacemakers:

Answer 3

anywhere below lower frequency

Question 4

ERP-

Answer 4

effective (absolute) refractory period, no new AP can be triggered

Question 5

chanellopathies

Answer 5

mutations in ion channels (mostly K+ Na+) responsible for AP generation; usually no apparent problem with heart function but responsible for 85% of Sudden Death Syndrome

Question 6

phases: systole:

Answer 6

(0.3 s)
isovolumetric contraction,
rapid ejection,
slow ejection

Question 7

phases: diastole:

Answer 7

(0.5 s)
isovolumetric relaxation,
rapid ventricular filling,
slow ventricular filling (diastasis)

Question 8

Principles, the cardiac cycle:

Answer 8

1. flow is directed downhill the pressure gradient

2. valves are opened and closed by the flow generated by the pressure difference

Question 9

Sequence, the cardiac cycle:

Answer 9

Pv - ventricular pressure;    
Pat – atrial pressure;     
Pao – aorta pressure;     
1.	Pv>Pat : mitral valve closes
2.	Isovolumetric contraction: both valves are closed
3.	Pv>Pao : aortic valve opens
4.	Rapid and reduced ejection
5.	Pv