Cardiac cycle Flashcards
List the structures involved in cardiac electrical conduction.
- Sino atrial node (SA) NODE - spontaneously and rhythmically imitate their own depolarisation, their characteristic rhythm is normal sinus rhythm, determines heart rate
- Atrioventricular node (AV) NODE - one place where the impulse can pass, as the impulse passes through the AV node is delayed for about 0.1 sec allowing the atria time to finish contracting.
- Atrioventricular bundle (BUNDLE OF HIS)
- Bundle branches left and right
-Purkinje fibres
Describe the properties of cardiac muscle which allow it to beat effectively.
- Have short, fat, branched fibres unlike skeletal muscle fibres
- Cardiac muscle fibres connect like sheets of corrugated iron at junctions called intercalated discs. This contrasts with skeletal muscle fibres which function independently
Intercalated discs contain - Gap junctions - which allow transmission of electrical impulses throughout the heart
P wave, describe the electrical and mechanical events they each represent.
P WAVE - Atrial systole and ventricular diastole (mechanical),
Atrial depolarisation (electrical)
-blood is forced through the mitral and tricuspid atrioventricular valves into the ventricles
QRS complex describe the electrical and mechanical events they each represent.
QRS - ventricular systole and atrial diastole (mechanical),
ventricular depolarisation and atrial repolarisation (electrical)
T complex describe the electrical and mechanical events they each represent.
Ventricular repolarisation (electrical), atria distole and ventricles distole (mechanical)
State the ranges for a normal heart rate.
60-100 beats/per min
Normal heart rate is approximately 75 beats/min
TACHYCARDIA: a heart rate greater than 100beats/min - exercise, stress, heart disease, raised body temperature, drugs.
BRADYCARDIA: a heart rate slower than 60beats/min - lowered body temperature, drugs, athletes.
