The Human
Cardiovascular System
*In preparation for a pig’s heart dissection
Larry M. Frolich, Ph.D.,Human Anatomy
Cardiovascular/Circulatory System:
• Principles
• Structures
• Two circuits
• Pulmonary
• Systemic
• Heart Details
• Other Details
CV System Function:
Circulate blood through entire body for
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Transport of oxygen to cells
Transport of CO2 away from cells
Transport of nutrients (glucose) to cells
Movement of immune system components
(cells, antibodies)
• Transport of hormones
How?
• Heart is pump
• Diffusion in
capillaries
Veins = Return
Arteries = Away
Overall Organization
• Heart/Great Vessels--1 Route
• Smaller arteries & veins --many routes
-collateral circulation
Walls of Arteries and Veins
• Tunica externa
– Outermost layer
– Strengthens, Anchors
• Tunica media
– Middle layer
– Vaso-constriction/dilation
• Tunica intima
– Innermost layer
– Minimize friction
• Lumen
Artery/Vein Differences
Arteries
Direction Blood Away from
of flow
Heart
Pressure Higher
Veins
Blood to Heart
Walls
Lumen
THICKER: Tunica
media thicker than
tunica externa
Smaller
THINNER: Tunica
externa thicker
than tunica media
Larger
Valves
No valves
Valves (see next)
Lower
Capillaries
• Microscopic: 1 cell thick
• Network
• Entire goal of C-V system is
to get blood into capillaries
where diffusion takes place
GREAT VESSELS
•Aorta
•IVC, SVC
•Pulmonary Trunk
•Pulmonary Veins
2 Circulatory Paths
heartarteries arterioles


veinsvenules capillaries
Systemic
Pulmonary
Heart Chambers and Valves
Larry M. Frolich, Ph.D.,Human
Anatomy
Right Heart Chambers: Pulmonary Circuit
• Right Atrium (forms most of posterior of heart)
– Receives O2-poor blood from body via IVC,
SVC, Coronary sinus
• Right Ventricle
– Receives O2-poor blood from right atrium
through tricuspid valve
– Pumps blood to lungs via Pulmonary Semilunar
Valve in pulmonary trunk
– Septum
Left Heart Chambers: Systemic Circuit
• Left Atrium
– Receives O2-rich blood from 4 Pulmonary Veins
• Left Ventricle (forms apex of heart)
– Receives blood from Left Atrium via bicuspid valve
– Pumps blood into aorta via Aortic Semilunar
Valve to body
Heart Valves: Lub*-Dub**
•
*Tricuspid Valve: Right AV valve
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3 Cusps (flaps) made of endocardium and CT
Cusps anchored in Rt. Ventricle by Chordae Tendinae
Chordae Tendinae prevent inversion of cusps into atrium
Flow of blood pushes cusps open
When ventricle in diastole (relaxed), cusps hang limp in ventricle
Ventricular contraction increases pressure and forces cusps closed
*Bicuspid (Mitral) Valve: Left AV valve
– 2 cusps anchored in Lft. Ventricle by chordae tendinae
– Functions same as Rt. AV valve
•
**Semilunar valves: prevents backflow in large arteries
– Pulmonary Semilunar Valve: Rt Ventricle and Pulmonary Trunk
– Aortic Semilunar Valve: Left Ventricle and Aorta
– 3 cusps: blood rushes past they’re flattened, as it settles they’re pushed
down (valve closed)
Location of Heart
in Thorax
Heart Wall
• Epicardium (most superficial)
– Visceral pleura
• Myocardium (middle layer)
– Cardiac muscle
– Contracts
• Endocardium (inner)
– Lines the heart
Blood supply to heart wall
• Rt and Lft Coronary Arteries
– Branch from Ascending Aorta
– Have multiple branches along heart
– Coronary Heart Disease
• Cardiac Veins
– Coronary Sinus (largest)
– Many branches feed into sinus
http://www.rmgh.net/wiki/images/4/4b/Coronary_arteries_and_cardiac_veins.gif
Chamber contraction/relaxation