Heart Activity Flashcards
What muscle cells make up the cardiac muscle?
Cardiomyocytes.
Is cardiac muscle smooth or striated?
Striated.
What discs join cardiac muscle cells together?
Intercalated discs.
What allows cardiac muscle to contract as a single unit?
The flow of ions between cells
What does cardiomyocytes require for contraction to occur?
Extracellular calcium ions.
Why does cardiac muscle contain the most mitochondria per cell?
So it can meet its energy requirements.
Why must the cardiac muscle contract in a coordinated fashion?
To ensure it pumps blood around the body efficiently.
What does the cardiac conduction system consist of?
- Sinoatrial node (SA node).
- Atrioventricular node (AV node).
- Bundle of His.
- The left and right bundle branches.
- The Purkinje fibres.
Which node does the electrical impulse that causes rhythmic contraction of heart muscle arise in?
SA node.
Explain the contraction of heart muscle (conduction system)?
1) . SA node –>
2) . Impulse spreads over the atrial muscles causing atrial contraction.
3) . Impulse carries on to AV node.
4) . Impulse is conducted to ventricular muscles via the bundle of His, bundle branches and the Purkinje fibres.
What happens during the cardiac cycle (heart beat)?
Heart contracts and then relaxes.
What is the period of contraction also known as?
Systole.
What is the period of relaxation also known as?
Diastole.
What are the 3 phases of the cardiac activity?
1) . Atrial systole = contraction of atria –> 0.1 seconds.
2) . Ventricular systole = contraction of the ventricle –> 0.3 seconds.
3) . Complete diastole = relaxation of the atria and ventricles –> 0.4 seconds.
