Electrical Activities of the Heart Flashcards Preview

Cardiovascular System > Electrical Activities of the Heart > Flashcards

Flashcards in Electrical Activities of the Heart Deck (23)
Loading flashcards...
1
Q

Are cardiac muscles able to exhibit tetanus (Y/N)

A

No

2
Q

Why are cardiac muscles not able to exhibit tetanus

A

Long refractory period and a long action potential which allows a period of relaxation and contraction

3
Q

What do cardiac muscles form

A

A functional syncytium

4
Q

What is a synctium

A

Cells are electrically connected via gap junctions

Physically connected by desmosomes to form intercalated discs

5
Q

What is used to regulate contraction

A

Ca2+

6
Q

Why is Ca2+ able to regulate contraction

A

Does not saturate troponin

7
Q

Non pacemaker resting membrane potential

A

High resting K+

8
Q

Non pacemaker initial depolarisation

A

Increase in Na+

9
Q

Non pacemaker plateau

A

Increase in Ca2+

Decrease in K+

10
Q

Non pacemaker repolarisation

A

Decrease in Ca2+ and increase in K+

11
Q

Pacemaker action potential

A

Increase in Ca2+ (L-type)

12
Q

Pacemaker pre-potential (3)

A

Gradual decrease in Pk+

  • Early increase in PNa+= PF
  • Late increase in PCa2+
13
Q

What does the pacemaker function explain

A

autorythmicity

14
Q

Modulators for electrical activity

A
Sympathetic & parasympathetic systems
Drugs
Temperature
Calcium
Potassium
15
Q

How does drugs modulate electrical activity

A

Ca2+ blockers- reduces force of contraction

Cardiac glycocides- increase force of contraction

16
Q

How does temperature modulate electrical activity

A

Increases 10 beats/min/C

17
Q

How does potassium modulate electrical activity

A

Hyperkalaemia: fibrillation and heart block

18
Q

How does calcium modulate electrical activity

A

Hypercalcaemia- High Ca2+ increased HR and force of contraction
Hypocalcaemia- low Ca2+ decreased HR and force of contraction

19
Q

What does the conducting system consist of

A
Sinoatrial node
Annulus fibrosus
Atrioventricular node
Bundle of his
Purkinje fibres
20
Q

Function of Sinoatrial node

A

Pacemaker

21
Q

Function of Annulus fibrosus

A

Non-conducting

22
Q

Function of Atrioventricular node

A

Delay box (0.05 m/sec)

23
Q

Function of Purkinje fibres

A

rapid conduction system (5m/sec)

Decks in Cardiovascular System Class (42):