Anatomy ∙ Physiology IIChapter 15,

Section 1The Cardiovascular

System

FUNCTIONS OF THE HEART

It pumps 7000L (1800 gallons) of blood through our body every day.

The heart contracts 2.5 billion times in a lifetime.

The heart is composed of two pumps

The pulmonary circuit carries blood to the lungs

The systemic circuit carries blood to the body

the heart is located within the mediastinum

1/3 2/3

It is about the size of a fist (14cm x 9cm)

2/3 of the heart is left of the midline

The heart is posterior to the sternum

Baseattachment of major vessels2nd intercostal space

ApexPointed inferior margin5th intercostal space

The heart is surrounded by a pericardial membrane.

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 contains 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

A pocket on each atrium, called the auricleincreases the capacity of the atria .

blood enters the heart through the great veins

The superior vena cava returns blood from the upper body 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

Four pulmonary veins return blood from the lungs to the heart

Great arteries carry blood away from the heart

The aorta delivers oxygenated blood to the systemic circulation

The pulmonary trunk* delivers deoxygenated blood to the lungs

*The pulmonary trunk immediately divides into a left and right pulmonary artery.

Left and right 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 anchored to the

cusps papillary muscles

Papillary muscles contract to pull the

valves tightly shut

AV valves are anchored to the ventricles by chordae tendineae

Mitral Valve Prolapse – cusp of the mitral valve 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 of blood into the ventricles

A pulmonary valve is located at the base of the pulmonary trunk

The semilunar valves close as the ventricles relax to prevent blood from entering the ventricles.

Each cusp of a semilunar valve is shaped like a crescent moon

path of blood through the right heart

1 .Blood enters right atrium through the SVC, IVC, and coronary sinus

2 .It passes through the tricuspid valve into the right ventricle

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

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path of blood through the left heart

5 .Oxygenated blood is returned to the heart through 4 pulmonary veins .

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9 .Blood enters systemic circulation to the tissues throughout the body .

6 .Blood enters the left atrium .

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7 .Blood passes through the bicuspid valve into the left ventricle .

8 .The left ventricle pumps blood through the aortic valve into the aorta.

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