1. Cardiac Physiology The heart: chambers, the valves
Cardiac muscle cells
Some cardiac muscle cells are autorhythmic
Arrangement of cardiac muscle cells
Excitation-contraction coupling

6. Atrioventricular (AV) Valves
guard the passageway between the atria and the ventricles
Tricuspid valve between right atrium and right ventricle
Bicuspid (mitral) valve between left atrium and left ventricle

7. Semilunar valves Between ventricles and arteries
Pulmonary valve between right ventricle and pulmonary artery
Aortic valve between left ventricle and aorta

9. All myocardial cells
Gap junctions at intercalated discs, waves of depolarization spread from one cell to another

11. Autorhythmic myocardial cells
(pacemakers) are small myocardial cells with few contractile fibers
Spontaneously generate action potentials
Enables the heart to contract without any outside signal
The heart is myogenic: signal for contraction originates from heart muscle itself

13. Most myocardial cells Remaining myocardial cells are striated
Have sarcomeres
Much smaller than skeletal muscle fibers
Connected by gap junctions at intercalated discs
Lots of mitochondria
Lots of blood flow to myocardial cells

14. More facts about myocardial cells
Large branching t-tubules
Sparse sarcoplasmic reticulum
Source of Ca++ is largely extracellular

15. Excitation-contraction coupling
Depolarization cell membrane voltage gated Ca++ channels open
 Ca++ enters cell
 calcium-induced calcium release: Ca++ released from SR
 Ca++ binds to troponin contraction

16. Myocardial cell relaxation
Ca++ dissociates from troponin
 Ca++ returns to SR by Ca++ ATPase
 Ca++ also transported from cell by Na+-Ca++ indirect active transport protein: Ca++ is exchanged for Na+, which moves in along its electrochemical gradientNa+ removed by active transport