Chapter 11 Heart and Circulatory System
• System which serves our transportation needs.
I. Heart
a. Contains four chambers
i. 2 Upper Atrium (Receiving chambers)
ii. 2 Lower Ventricles (Discharging chambers)
b. Made up of three layers
i. Myocardium – Bulk of heart muscle
ii. Endocardium – Inner lining of heart chamber which comes in contact with blood
iii. Epicardium – Outer layer
c. Pericardium - Two layered sac which surrounds the heart.
i. Parietal – Outer Layer
ii. Visceral – Inner layer
II. Heart Valves
a. Atrioventricular Valves
i. Bicuspid (Mitral) Valve – Between left atrium and ventricle
ii. Tricuspid Valve – Between right atrium and ventricle
1. AV Valves prevent backflow of blood (Murmur)
2. Chordae Tendinae – Cordlike structures which attach valves to heart wall
b. Semilunar Valves – Located between ventricles
i. Pulmonary semilunar valve – Located at beginning of pulmonary artery and allows blood to flow out of right ventricle
ii. Aortic semilunar valve – Located at beginning of aorta and allows blood to flow out of left ventricle into aorta.
III. Blood Flow Through Heart
IV. Heart Actions
a. Systole – Contractionb. Diastole – Relaxation
V. Heart Sounds
a. Lub Dub – Rhythmical and Repetitive sounds given off by heart actions.
i. LUB – First sound caused by vibration and closure of AV valves
ii. DUB – Second sound caused by closure of both semilunar valves.
iii. SWOOSH – Sound between LUB DUB indicating heart murmur.
VI. Circulation
a. Pulmonary Circulation – Blood flow from Right Ventricle to Lungs (Oxygenation)
b. Systemic Circulation – Blood flow from Left Ventricle to Body
VII. Coronary Circulation
a. Delivery of blood and oxygen to heart tissue.
b. Blood enters through coronary arteries.
c. Myocardial Infarction – Occurs when heart is deprived of nutrients (glucose) and oxygen. (Heart Attack)
d. Angina Pectoris- Severe chest pains that occur when myocardium is deprived of oxygen.
e. Coronary Bypass – Treatment for those who suffer coronary blockages.
VIII. Blood Vessels
a. Arteries – Vessels which transport blood away from the heart.
b. Arterioles – Small arteries which branch off main arteries
c. Capillaries – Carry blood from arterioles to venules. Sites of gas exchange between blood and tissues.
d. Venules – Vessels which transport blood from capillaries to veins.
e. Veins – Vessels which transport blood to heart.
IX. Longest Vein
a. The branches of the “Great Saphenous Vein” are cut and used for heart bypass surgeries
X. Anatomy of Blood Vessels
a. Arteries and Veins
i. Tunica interna – Inner layer of endothelial cells
ii. Tunica media – Smooth muscle (Thicker in arteries)
iii. Tunica externa – Elastic tissue (Thicker in veins)
b. Capillaries
i. Thin layer of endothelial cells
XI. Physiology of Blood Vessels
a. Arteries and Arterioles
i. Distribute blood from heart
ii. Maintain blood pressure by constricting or dilating
iii. Walls are strong, thick and somewhat elastic
b. Veins and Venules
i. Collect blood from capillaries and return it to heart
ii. Serve as blood reservoirs because they can expand to hold larger volumes of blood
iii. Unlike arteries, veins have a series of valves to keep blood from back flowing during circulation
iv. Pressure is lower in veins compared to arteries and thus backflow is more prevalent.
c. Capillaries
i. Exchange vessels – walls are so thin that blood cells travel through in a single file
ii. Transport glucose and oxygen out of blood into cells
iii. CO2 and waste into capillaries from cells.