Chapter 11, The Heart, Part A

Chapter 11
Part A: The Heart
1. Where is it?
a. Location—thorax between the lungs in the inferior mediastinum
b. Orientation—pointed apex directed toward left hip
c. Size—about the size of your fist
2. Coverings
a. Pericardium—a double-walled sac:
i. Fibrous pericardium is loose and superficial
ii. Serous pericardium is deep to the fibrous pericardium and composed of two layers:
1. Visceral pericardium (lines organ)
a. Next to heart; also known as the Epicardium
2. Parietal pericardium (surrounds chamber)
a. Outside layer that lines the inner surface of the fibrous pericardium
b. Serous fluid fills the space between the layers of pericardium
3. Heart Structure
a. The heart wall:
i. Epicardium
1. Outside layer = visceral pericardium
2. Connective tissue
ii. Myocardium
1. Middle layer
2. Mostly cardiac muscle
iii. Endocardium
1. Inside layer
2. Endothelium
b. Heart Chambers
i. Right and left side act as separate pumps
ii. Four chambers
1. Two atria
a. Receiving chambers
b. Right and left atrium
2. Two ventricles
a. Pumping chambers
b. Right and left ventricle
c. Heart septa
i. Interventricular
1. Separates the two ventr=icles
ii. Interatrial septum:
1. Separates the two atria
d. Heart valves
i. Purpose—allows blood to flow in only one direction to prevent backflow
ii. Four valves
1. Atrioventricular (AV) valves—between atria and ventricles:
a. Bicuspid (mitral) valve (left side of heart)
b. Tricuspid valve (right side of heart)
2. Semilunar valves—between ventricle and artery:
a. Pulmonary semilunar valve (going to lungs)
b. Aortic semilunar valve
3. AV valve details
a. Anchored in place by Chordae tendineae (“heart strings”)
b. Open during heart relaxation and closed during ventricular contraction
4. Semilunar valve details
a. Open during ventricular contraction and closed during heart relaxation
b. Operate opposite of one another to force a one-way path of blood through the heart
4. Systemic and pulmonary circulations
a. Systemic circulation:
i. Blood flows from the left side of the heart through the body tissues and back to the right side of the heart
b. Pulmonary circulation:
i. Blood flows from the right side of the heart to the lungs and pack to the left side of the heart
5. Great vessels
a. Arteries
i. Aorta
ii. Pulmonary artery
b. Veins
i. Superior/inferior venae cavae
ii. Pulmonary veins
6. Blood flow through the heart
a. From venae cavae
b. From right atrium
c. From right ventricle
d. From pulmonary trunk
e. In the lungs
f. From the lungs
g. From left atrium
h. From left ventricle
7. Coronary circulation
a. Own nourishing system for heart walls
b. Coronary arteries
c. Cardiac veins
d. Coronary sinus
8. Heart conduction system
a. Intrinsic
b. No nerve impulses
c. Sinoatrial (SA) node
d. Atrioventricular (AV) node
e. AV bundle
f. Purkinje fibers
g. Heart contractions
i. Initiation
ii. Autorhythmic cells
iii. Cardiac depolarization
iv. Irregularities
1. Tachycardia
2. Bradycardia
9. Cardiac cycle
a. Sequence
b. Systole
c. Diastole
d. Lubb dupp = heart sounds
i. Lubb
ii. Dupp