D’YOUVILLE COLLEGE
BIOLOGY 108/508 - HUMAN ANATOMY & PHYSIOLOGY II
LECTURE # 16
CARDIOVASCULAR SYSTEM
GENERAL ORGANIZATION - HEART ANATOMY
1.
Introduction:
• cardiovascular system = heart + blood vessels
Heart: filled by blood from veins; pumps blood into arteries
Arteries: convey blood away from heart
Veins: convey blood toward heart
Microcirculation: microscopic capillaries; site of exchange between blood
and tissues; fed by arterioles (smallest arteries); drained by venules (smallest veins)
(fig. 19 - 1)
Two Circuits (fig. 18 - 5):
a. Pulmonary Circuit: conveys oxygen-poor blood from right heart to lung;
returns oxygen-rich blood to left heart (fig. 19 - 19)
b. Systemic Circuit: conveys oxygen-rich blood from left heart to rest of body;
returns oxygen-poor blood to right heart (fig. 19 - 20)
2. Heart Anatomy: heart is a double pump consisting of four chambers (located in
the mediastinum of the thorax) (figs. 18 - 1 & 18 - 4):
a. Right Atrium: receives from systemic circuit via: superior vena cava (drains
head, neck, thorax and upper limbs), inferior vena cava (drains abdomen, pelvis and
lower limbs), coronary sinus (drains wall of heart)
• feeds right ventricle via atrioventricular (AV) orifice - right AV
(tricuspid) valve
b. Right Ventricle: pumps to pulmonary trunk; thinner walled due to lower
pressures required to irrigate pulmonary circuit; opening to pulmonary trunk
controlled by pulmonary semilunar (SL) valve
c. Left Atrium: receives from pulmonary circuit via four pulmonary veins (left
and right, superior and inferior)
• feeds left ventricle via AV orifice - left AV (bicuspid or mitral) valve
d. Left Ventricle: pumps to systemic circuit via aorta (largest artery in the
body); thicker walled due to high pressures required to irrigate systemic circuit;
aortic opening controlled by aortic semilunar valve
Coverings and Wall Layers (fig. 18 - 2):
• heart enclosed in double sac consisting of parietal and visceral pericardia
• wall has 3 layers: epicardium, myocardium, & endocardium (heart valves)
Internal Features (fig. 18 - 4e):
• ventricular myocardia are laced with trabeculae carneae and finger-like
intrusions (papillary muscles) that attach to free margins of AV valves via tiny
tendons (chordae tendineae)
• interatrial and interventricular septa separate right and left sides of heart
Coronary Circulation (fig. 18 - 7):
Bio 108
lec. 21 - p. 2
• left coronary artery supplies anterior interventricular and circumflex)
• right coronary artery supplies posterior interventricular & marginal)
- coronary circulation drained by cardiac veins that feed coronary sinus