1. Anatomy and Physiology
Chapter 20: The Heart

2. Introduction Heart beat 100,000X / day ( moves 8000L)
Muscle is never at rest
Pulmonary circuit goes to heart from lungs
Systemic circuit goes to heart from body
Arteries (afferent) – away from the heart
Veins (efferent) – toward the heart
Capillaries – exchange vessels

3. 20.1 Anatomy of the Heart Tilts to left of sternum
Between intercostal spaces 3 and 5
Associated with lots of fatty tissue
Pericardial sac – protects and lubricates (fluid)
Myocardium = heart muscle
Coronary arteries = supply blood to heart muscle itself ( these are “bypassed”)

5. Chambers and vessels KNOW THIS
Superior vena cava – blood from head/neck/limbs to RA
Right Atrium – receives blood from body
Right ventricle – pump * / to lungs
Left Atrium– from lungs
Left ventricle – pump * / to body through; thicker more muscular side… to whole body
Aorta
Inferior vena cava – receives blood from the trunk to RA
* RV and LV pump at same time, same amount

7. Important information
Be able to label the diagrams at end of ch. 20 on page 705 – there will be a heart diagram to label on the test, like the ones you colored and the one on pg 705. You will have a word bank.

8. Chambers, vessels and valves
RA and RV separated by tricuspid valve
Cusps anchored to chordae tendineae that tug flaps down to prevent backflow
LA receives blood through mitral valve
LV is associated with semilunar valve

10. 20.2 Generation of Action Potentials
Muscle cells in conducting system coordinate beat
Contractile cells contract to propel blood
Electrocardiograph (ECG, EKG) shows electrical events of heart beat
App called cardiograph

11. Sinoatrial (SA) node in RA
Spontaneous depolarization without neural or hormonal
80 – 100 action potentials per minute
Pacemaker cells
Atrioventricular (AV) node between A and V
50 msec from SA to AV
Delay at AV node so atria finish contracting before ventricles
Conducting cells with internodal pathways do not have stable resting potential; drift toward threshold
Purkinje fibers
Rapid conduction of action potentials ventricular myocardium

12. Summary of gates and Action Potential in Cardiac Muscle
1. rapid deploarization
Opening of fast Na channels
2. plateau
Slow Ca channels
3. repolarization
Slow P channels

17. Energy
Heart muscles have lots of mitochondria that break down both fatty acids and glucose (stored as glycogen)
Have heme units (part of hemoglobin) stored as myoglobin so they can have access to lots of O2 – very aerobic
Calcium ions are very important to the conduction of action potentials in the cardiac muscle cells