Download - Section 1, Chapter 15
Anatomy · Physiology II
Chapter 15, Section 1
The Cardiovascular System
The heart is a remarkable organ
It pumps 7000L (1800 gallons) of blood through our body every day
The heart contracts 2.5 billion times in a lifetime
The heart contains two pumps
The heart is located within the mediastinum
• It is about the size of a
fist (14cm x 9cm)
• 2/3 of the heart is left of
the midline
1/3 2/3
The heart is posterior to the sternum
Base
attachment of major vesselsattachment of major vessels
2nd intercostal space
Apex
Pointed inferior margin
5th intercostal space
A pericardial membrane surrounds the heart.
The fibrous pericardium forms a thick outer layer
of connective tissue.
The parietal pericardium is a serous membrane
attached directly to the fibrous layer.
A visceral pericardium is a serous membrane that
forms the outer layer of the heart wall.
The pericardial cavity contains serous fluid.
The wall of the heart contains 3 layers
The epicardium is also called the visceral pericardium
The myocardium contains a thick layer of cardiac muscle,
with blood vessels and nerves
The endocardium is a smooth layer of squamous
epithelium that lines the heart chambers and valves
The heart has 4 chambers
The left atrium receives
blood from the lungs
The right atrium
receives blood from the
body
The left ventricle pumps
blood towards the body The right ventricle pumps
blood towards the lungs
Interventricular septum
Auricles increase the volume of the atria
Great veins carry blood towards the heart
The superior vena cava
returns blood from the
upper body to the heart
The inferior vena cava
Four pulmonary veins
return blood from the lungs
to the heart
The inferior vena cava
returns blood from the
lower body to the heart
The coronary sinus
returns blood from the
myocardium to the heart
Great arteries carry blood away from the heartGreat arteries carry blood away from the heart
The aorta conveys
oxygenated blood to the
systemic circulation
The pulmonary trunk* conveys
deoxygenated blood to the
pulmonary circulation
* The pulmonary trunk immediately divides
into a left and right pulmonary artery.
AV* valves prevent backflow into the atria. AV* valves prevent backflow into the atria.
The tricuspid valve
guards the right AV
orifice
The bicuspid (mitral)
valve guards the left
AV orifice
*AV = atrioventricular
Chordae tendineae anchor the cusps papillary muscles
Papillary muscles contract to pull the valves tightly shut
AV valves are anchored to the ventricles
Mitral Valve Prolapse – cusp protrudes into atrium.
Symptoms include: chest pain, heart palpitations,
and fatigue.
An Aortic valve (not shown) is
located at the base of the aorta
Semilunar valves prevent backflow into the ventricles
A pulmonary valve is located at A pulmonary valve is located at
the base of the pulmonary trunk
Semilunar valves prevent backflow into the ventricles
Each cusp of a semilunar
valve is shaped like a
crescent moon
Path of blood through the right heart chambers
1. Blood from SVC & IVC enter the
right atrium.
2. It passes through the tricuspid valve
into the right ventricle4
4
3. Blood is pumped from the right
ventricle, through the pulmonary
valve, and into the pulmonary trunk.
4. Blood passes into the pulmonary
arteries towards the lungs
1
2
3
Path of blood through the left heart chambers
5. Oxygenated blood is returned to
the heart through 4 pulmonary veins.
6. Blood enters the left atrium.
7. Blood passes through the bicuspid
valve into the left ventricle. 8
9
99
55
9. Blood enters systemic circulation to
the tissues throughout the body.
68. The left ventricle pumps blood
through the aortic valve into the aorta.
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