Heart Anatomy Lecture - ECC-BOOK - Extracorporeal Circulation ...

• Circulatory system
The Heart
– heart, blood vessels and blood
• Cardiovascular system
– heart, arteries, veins and capillaries;
2 major divisions
• Pulmonary circuit - right side of heart
– carries blood to lungs for gas exchange
• Systemic circuit - left side of heart
– supplies blood to all organs of the body

Cardiovascular System Circuit

• muscular pump
• size of a fist
• weighs 10 oz.
Size, Shape and Position
• located in mediastinum,
area between the lungs
• base - broad superior
portion of heart
• apex - inferior end, tilts to
the left, tapers to point

Heart Position

United States
National Library of Medicine's Visible Human Project
Joseph Jernigan, a convicted murderer, died by lethal injection in 1993.
He was 39 years old. His body was encased in gelatin, frozen, and carved
into 1,862 transverse (horizontal) slices. Each millimeter-thin section was
photographed, digitized, and electronically reassembled to create the
"Visible Human Male," part of the National Library of Medicine's Visible
Human Project.
In 1995, a 59-year-old Maryland woman became the first "Visible Human
Female."
Doctors use these "Visible Humans" to plan surgeries. Medical students
study their anatomy.
http://www.exploratorium.edu/bodies/vhuman.html
http://www.nlm.nih.gov/research/visible/visible_human.html
http://collab.nlm.nih.gov/webcastsandvideos/visiblehumanvideos/visiblehu
manvideos.html

Section through Visible Human Male
thorax, including heart (with muscular left ventricle),
lungs, spinal column, major vessels, musculature
http://www.nlm.nih.gov/research/visible/photos.html
http://www.nlm.nih.gov/research/visible/image/thorax.jpg

Pericardium
• Allows heart to beat without friction, room to
expand and resists excessive expansion
• Parietal pericardium
– outer, tough, fibrous layer of CT
– inner, thin, smooth, moist serous layer
• Pericardial cavity
– filled with pericardial fluid
• Visceral pericardium (a.k.a. epicardium of heart wall)
– thin, smooth, moist serous layer covers heart surface
• Pericarditis

Pericardium & Heart Wall
Parietal pericardium
• Pericardial cavity contains 5-30 ml of pericardial fluid

Heart Wall
• Epicardium (a.k.a. visceral pericardium)
– serous membrane covers heart
• Myocardium
– thick muscular layer
– fibrous skeleton - network of collagenous and elastic
fibers
• provides structural support
• attachment for cardiac muscle
• nonconductor important in coordinating contractile activity
• Endocardium
– smooth inner lining

Pericardium & Heart Wall
Parietal pericardium
• Pericardial cavity contains 5-30 ml of pericardial fluid

• 4 chambers
• Right and left atria
Heart Chambers
– 2 superior, posterior chambers
– receive blood returning to heart
from veins, veins carry blood back
to the heart
• Right and left ventricles
– 2 inferior chambers
– pump blood into arteries, arteries
carry blood away from the heart
• Atrioventricular (coronary) sulcus - separates atria from
ventricles
• Anterior and posterior interventricular sulci - grooves
separate ventricles

External Anatomy - Anterior
Atrioventricular
sulcus

Anterior Aspect

External Anatomy - Posterior

Heart Chambers - Internal
• Interatrial septum
– wall that separates atria
• Interventricular septum
– wall that separates ventricles
• Trabeculae carneae
– internal ridges in both ventricles

Internal Anatomy Anterior Aspect

Trace a Drop of Blood
• Deoxygenated blood enters the right side of the
heart via the superior vena cava and the inferior
vena cava
• Right atrium
• Right atrioventricular (AV) valve (tricuspid valve)
• Right ventricle
• Pulmonary semilunar valve
• Pulmonary circuit
– Pulmonary trunk
– Pulmonary arteries to lungs
– Pulmonary veins returning from lungs

Trace a Drop of Blood
• Oxygenated blood enters the left side of the heart
via the pulmonary veins returning from lungs
• Left atrium
• Left AV valve (mitral valve, bicuspid valve)
• Left ventricle
• Aortic semilunar valve
• Systemic circuit
– Aorta
– Other systemic vessels
– Superior vena cava and inferior vena cava
• Back to right atrium

Cardiovascular System Circuit

Blood Flow Through Heart

Heart Valves
• Ensure one-way blood flow
• Atrioventricular (AV) valves (2)
– right AV valve has 3 cusps (tricuspid valve)
– left AV valve has 2 cusps (mitral, bicuspid valve)
– chordae tendineae - cords connect AV valves to papillary
muscles (on floor of ventricles)
• Semilunar valves - control flow into great arteries
– Pulmonary semilunar valve: from right ventricle into
pulmonary trunk
– Aortic semilunar valve: from left ventricle into aorta

Internal Anatomy, Anterior Aspect

Heart Valves

Heart Internal Anatomy
• Heart bisected in frontal plane, opened like a book

Heart Valves

AV Valve Mechanics
• Ventricles relax, pressure drops, semilunar valves
close, AV valves open, blood flows from atria to
ventricles
• Ventricles contract, AV valves close (papillary m.
contract and pull on chordae tendineae to prevent prolapse),
pressure rises, semilunar valves open, blood flows
into great vessels

Operation of Atrioventricular Valves

Operation of Semilunar Valves

• Mitral regurgitation
Valve Diseases
– When left AV valve (bicuspid valve) can’t remain tightly
closed
– Blood leaks back into left atrium
• Mitral stenosis
– Narrow left AV valve (biscupid valve) due to scar tissue
– Hypertension

Coronary Circulationblood
supply to the heart
• Blood vessels nourish cardiac muscle
• Coronary arteries
– Distribute oxygenated blood to the heart
– First branch off the base of the aorta
– Deliver blood to the heart when the heart is relaxing
– Right coronary artery (larger than left), 2 branches
– Left coronary artery (smaller than right), 2 branches
– Coronary bypass surgery
• Needed when circulation to the heart is blocked
• reroutes, or "bypasses," blood around clogged arteries to
improve blood flow and oxygen to the heart
http://www.americanheart.org/presenter.jhtml?identifier=4484

Myocardial Infarction
• Myocardial infarction (MI) - sudden death of heart
tissue caused by interruption of blood flow from
vessel narrowing or occlusion
• Anastomoses - anatomical convergence, the
opposite of branch (Example: a point where two
blood vessels merge and combine their
bloodstreams)
– defend against interruption of blood flow to the heart by
providing alternate blood pathways; if one artery becomes
obstructed, blood continues to reach myocardial tissue
through an alternative route

Coronary Circulationblood
supply to the heart
• Cardiac veins
– Collect deoxygenated blood from the heart
– Empties into coronary sinus
• Coronary sinus empties into the right atrium

Coronary Vessels - Anterior

Coronary Vessels - Posterior