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All muscle is innervated by __.
Explain nerves in terms of muscles.
- i. Smooth and skeletal muscle will not contract unless the nerves stimulate them
- ii. Although cardiac muscle has innervation, the nervous system doesn’t control the contractions; that is the job of the conduction system of the heart
- 1. Autonomic speeds up or slows down the heart rate
What are the conduction systems responsible for?
a. Responsible for the rhythmic contraction of the chambers and its made up of specialized cardiac muscle cells that act like neurons in that they can stimulate the rest of the cardiac muscle (myocardium) to contract
True or False:
The conduction system is the contraction cycle.
a. IT IS NOT THE CONTRACTION CYCLE; IT IS RESPONSIBLE FOR THE CONTRACTION CYCLE
Explain the SA node
- i. Normal pacemaker
- ii. Regulates heartbeat
- iii. Doesn’t need a stimulus
What happens when the SA gets triggered?
- 1. sends info down interatrial fiberes to AV node
- a. When down there, the whole atrial muscle mass gets stimulated to contract
- i. While that’s contracting, the stimulation is moving down the Bundles of His and up the Perkinje fibers
- 1. Not until it’s at the Perkinje fibers that the ventricles get excited
- a. Excitation at this point has passed over atria
Excitation of cardiac conduction system in terms of atria and ventricles.
- i. NOT EXCITED AT SAME TIME
- ii. ATRIAL EXCITATION, THEN VENTRICULAR EXCITATION
What are hte parts of the cardiac conduction system?
- a. SA Node
- b. Interatrial Fibers
- c. Atrioventricular Node
- d. Bundles of His
- e. Perkinje Fibers
Explain the atrioventricular node.
- i. Can act as alternate pacemaker, but it’s a slower beat
- ii. In floor of right atrium
Explain the Bundles of His
i. Fibers that are in the introventricular septum
What are the components of hte conduction system in the left atrium?
there are no components of conduction system in left atrium