The heart and ECG Flashcards
What is systemic circulation?
blood from heart via the body to provide 02 & nutrients
What do valves allow?
unidirectionality and maintain pressure
what is the circulation system in the body?
1) de02 blood enter right atria via Superior/ inferior Vena cava
2) blood enter right ventr. via tricuspid valve
3) blood exit right ventr. into pulmonary artery via Semi Lunar valve
4) blood to lungs
5) blood from lungs to left atria via pulmonary vein
6) blood from left atria to ventr. via Bicuspid Mitral valve
7) blood from left ventr. to aorta via semi lunar aortic valve for systemic circulation
What does myogenic mean?
signals itself and autorhythmic
What are pacemaker cells?
- create Action potentials
- located SA node in right atrium and AV node near tricuspid valve
What speed do Purkinje fibres conduct potential?
4m/s
What is systole?
when heart contracts and pumps blood into arteries
What is Diastole?
when heart relaxes and allows chambers to fill with blood
What is action potential transmission?
pacemakers> conduction fibres> contractile cells
how is passage to cardiac cells enabled?
cardiac muscle cells connected by gap junction channels
What are gap junction channels in cardiac cell?
Desmosomes ( protein fibres)
What do desmosomes allow?
myocardium can resist stretching
How is impulse initiated in heart?
1) SA node initiate impulse to AV node via conduction fibres
2) Small delay as AV node transmits less rapid
3) AV node > bundle of his in interventricular system
4) signal split into right and left branch
5) signal travel via Purkinje fibres which spread via Ventricles
Is there a steady resting potential?
NO
What happens with Action potential?
slow depolarisation
threshold reach= rapid action potential
Repolarization until -70mV
