Anatomy of
the Heart
STD 3251.4.2: Explore the anatomy of the heart and
the pathway of blood through this organ.
Heart Function
• Generates the pressure that propels blood
thru blood vessels
• Keeps oxygenated and deoxygenated blood
separate
• Helps regulates the body’s blood supply.
Human Heart
• Weighs less than a pound
–About the size of a fist
• Hollow, cone shaped organ
• Within the mediastinum
– the medial cavity of the thorax
Landmarks
• Apex
– Rests on the diaphragm
– Points toward the left hip
• Base
– Points towards the right shoulder
• The heart is
– Medial to the lungs
– Anterior to the esophagus and vertebrae
– Posterior to the sternum.
Heart Coverings
• Enclosed by the double layered pericardium
– Fibrous pericardium
• outermost layer, protects and anchors
– Serous pericardium
• 2 layered serous membrane.
– Parietal pericardium outer
– Visceral pericardium, a.k.a. the epicardium
Heart Wall
• 3 Layers
– Epicardium (visceral pericardium)
• Outer layer - Simple squamous epithelium
– Myocardium
• Middle layer
• Fibrous skeleton & Cardiac muscle
– Endocardium
• Thin, inner layer - simple squamous epithelium
• Lines chambers, continues into blood vessels
Heart Coverings and Wall
Heart Chambers
• 4 hollow chambers
– 2 Atria
• Receiving chambers
• Low pressure
– 2 Ventricles
• Thick walled
• Pumps of heart
Pulmonary circulation
• Runs between the heart and the lungs
RIGHT SIDE of heart
1.
2.
3.
4.
Right
ventricle
Deoxygenated blood from veins enter venae cavae
Pumps through pulmonary trunk
Splits into pulmonary arteries (to lungs)
Pulmonary veins carry blood back to left side of
heart
Pulmonary
trunk
Pulmonary
arteries
Pulmonary
capillaries
Pulmonary
veins
Left atrium
Systemic circulation
• Runs between the heart and body tissues
LEFT SIDE of heart
1.
2.
3.
4.
Left
ventricle
Blood from left atria enters left ventricle
Blood leaves heart by aorta
Aorta branches into systemic arteries
Blood returns to heart by systemic veins
Aorta
Systemic
arteries
Systemic
capillaries
Systemic
veins
Venae
cavae
Right
atrium
Circulation
Heart Valves (4)
• One direction flow
– Atria to ventricles (AV valves)
• Left AV valve (mitral)
–Bicuspid (2 flaps)
• Right AV valve
–Tricuspid (3 flaps)
– Semilunar valves
• Separates ventricles from their great vessels
–Pulmonary semilunar valve
–Aoritc semilunar valve
Heart Valves
AV Valves
•Closed during contraction
•Open during relaxation
Semilunar Valves
•Open during contraction
•Closed during relaxation
Cardiac Circulation
• Blood pumping through heart doesn’t directly
nourish heart!
•Coronary arteries
•Base of aorta
•Supply oxygen
•Cardiac veins
•Drain myocardium
•Empties into right atrium