chapter 21 - anatomy of the heart

what is the major function of the cardiovascular system

• transportation

what does the cardiovascular system us as the transport vehicle

• blood

what does the blood in the cardiovascular system carry

• oxygen, nutrients, cell wastes, electrolytes, and many other substances vital to the body’s homeostasis to and from the body cells

what is the propulsive force of the cardiovascular system

• contracting heart

what can the heart be compared

to a muscular pump equipped with one-way valves

as the heart contracts, it forces blood into

• a closed system of large and small plumbing lubes (blood vessels) within which the blood is confined and circulated.

what is the description of the heart

• cone-shaped organ approximately the size of a fist

where is the heart located

• within the mediastinum of the thorax

what is the heart flanked laterally by

• the lungs

what is the heart flanked posteriorly by

• the vertebral column

what is the heart flanked anteriorly by

• the sternum

it’s more pointed apex extends slightly to the ____ and rests on the ________, approximately at the level of the ______ ________ _______

• left

• diaphragm

• 5th intercostal space

the heart’s broader base, from which the ______ _______ emerge, lies beneath the ______ ____ and points towards the _____ __________

• great vessels

• second rib

• right shoulder

the heart is enclosed within a double-walled sac called the

pericardium

what is the loose superficial part of the pericardium

• the fibrous pericardium

what is deep to the fibrous pericardium

• the serous pericardium

what does the serous pericardium line the internal surface of the fibrous pericardium as

a parietal layer

apex versus base of heart

apex is bottom sharp part, base is top broad part

at the base of the heart, the parietal layer does what?

• reflects back to cover the external surface of the heart as the visceral layer or epicardium

serous fluid produced by the fibrous pericardium, parietal layer, and visceral layer allows

• the heart to beat in a relatively frictionless environment

the calls of the heart are composed of which 3 layers

• epicardium

• myocardium

• endocardium

epicardium description and aka

• aka: visceral pericardium

• outer layer

myocardium description

• the middle and thickest layer

• composed mainly of cardiac muscle

• Striated, has intercalated discs, under involuntary control

  • Fibrous skeleton composed of a dense network of fibrous connective tissue

  that supports the cardiac muscle fibers and heart valves

what reinforces the myocardium

• a dense fibrous connective tissue, called the cardiac skeleton

where is the cardiac skeleton thicker

• thicker around the heart valves and the base of the great vessels leaving the heart

endocardium description

• inner lining of the heart, which covers the heart valves and is continuous with the inner lining of the greater vessels

what is the endocardium composed of, like what types of cells

• simple squamous epithelium resting on areolar connective tissue

the heart is divided into 4 chambers separated into

• two superior atria (plural for atrium)

• and two inferior ventricles

the septum that divides the heart longitudinally is referred to as

• the interatrial septum where it separates the atria

• and the interventricular septum where it separates the ventricles

what are the atria good at functionally and what are they relatively ineffective as

• atria are receiving chambers

• are relatively ineffective as pumps

what are the ventricles good at

• the inferior thick-walled ventricles which form the bulk of the heart, are the discharging chambers

• blood our of the bean into the large arteries that emerge from its base

what do the 4 valves in the heart enforce

a one-way blood flow through the heart chambers

what are the two types that the 4 valves fall into

• atrioventricular (AV) valves and

• semilunar (SL) valves

where are the atrioventricular (AV) valves located

• located between the atrium and the ventricle on the left and right side of the heart

what are the two AV or atrioventricular valves called

• right AV is tricuspid valve

• left AV is mitral valve or bicuspid valve

the tricuspid valve has 3 flaplike cusps anchored to the ______ ______ of the ventricular wall by tiny, white collagenic chords called ______ ______

• papillary muscles

• chordae tendineae (literally “string hearts“)

the mitral valve has two flaplike cusps anchored to the ______ _______ by ________ _________

• papillary muscles

• chordae tendineae

what are the AV valves like when blood is flowing into the atria and the ventricles are relaxed

• AV valves are open and hang into the ventricles

what are the AV valves like when the ventricles contract and the blood in the ventricles is compressed

• this causes the AV valves to move superiorly and close the opening between the atrium and the ventricle

how do the chordae tendineae and the papillary muscles help prevent backflow of blood when the AV valves close

• The chordae tendineae, pulled tight by the contracting papillary muscles, anchor the cusps in the closed position and prevent the back- flow of blood from the ventricles into the atria

• If unanchored, the cusps would move upward into the atria like au umbrella being turned inside out by a strong wind.

where are the semilunar (SL) valves located

• between a ventricle and a great vessel

Pulmonary (SL) valve

• Has three pocketlike cusps located between the right ventricle and the pulmonary trunk.

aortic (SL) valve

• has three pocketlike cusps located between the left ventricle and the aorta.

when the contraction of the ventricles pushes blood into the great vessel, what are the SL valves like

• the SL valves are open and flattened against the wall of the vessel

when the ventricles relax, blood flows backward towards the ventricle and the cusps fill with blood, leading to

• the closing of the SL valves

what does the closing of the SL valves prevent

• backflow of blood from the greater vessels into the ventricles

the heart functions as a

double pump

what does the right side of the heart do

• The right side of the heart pumps oxygen-poor blood entering its chambers to the lungs to unload carbon dioxide and to pick up oxygen.

what do the blood vessels that carry blood to and from the lungs form

• the pulmonary circuit

what is the function of the pulmonary circuit

• strictly to provide for gas exchange

what does the left side of the heart do?

• pumps oxygenated blood returning from the lungs to the body tissue

what do the blood vessels that carry blood to and from all body tissues form?

• systemic circuit

what is the first step in blood flow through the right side of the heart (pulmonary circuit)

• right atrium receives oxygen-poor blood from the body via the venae cavae (superior vena cava and inferior vena cava) and the coronary sinus

what is the second step in blood flow through the right side of the heart (pulmonary circuit)

• from the right atrium, blood flows through the tricuspid valve lo the right ventricle.

what is the 3rd step in blood flow through the right side of the heart (pulmonary circuit)

• From the right ventricle, blood flows through the pulmonary valve into the pulmonary trunk.

what is the 4th step in blood flow through the right side of the heart (pulmonary circuit)

• The pulmonary trunk branches into left and right pulmonary arteries, which carry blood to the lungs, where the blood unloads carbon dioxide and picks up oxygen.

what is the 5th step in blood flow through the right side of the heart (pulmonary circuit)

• Oxygen-rich blood returns to the heart via four pulmonary veins.

what is the 6th step in blood flow through the now the left side of the heart (systemic circuit)

• Oxygen-rich blood enters the left atrium via four pulmonary veins.

what is the 7th step in blood flow through now the left side of the heart (systemic circuit)

• From the left atrium, blood flows through the mitral valve to the left ventricle.

what is the 8th step in blood flow through now the left side of the heart (systemic circuit)

• From the left ventricle, blood flows through the aortic valve to the aorta.

what is the 9th step in blood flow through now the left side of the heart (systemic circuit)

• Oxygen-rich blood is delivered 10 the body tissues by the systemic arteries.

even though the heard chambers are almost continually bathed with blood, his contained blood doesn’t nourish the

• myocardium

The functional blood supply of the heart is provided by the

coronary arteries

Right coronary artery (RCA) description

• Branches from the ascending aorta just above the aortic valve and encircles the heart in the coronary sulcus

Right coronary artery (RCA) areas supplied/branches

• Its branches include the right marginal artery and the posterior interventricular artery.

Right marginal artery description

Branches off the RCA and is located in the lateral portion of the right ventricle.

Right marginal artery areas supplied/branches

Supplies the lateral right side of the heart.

Posterior interventricular artery description

• Branches off the RCA and is located in the posterior interventricular sulcus.

Posterior interventricular artery areas supplied/branches

• Supplies the posterior walls of the ventricles and the posterior portion of the interventricular septum.

• Near the apex of the heart it merges (anastomoses) with the anterior interventricular artery.

Left coronary artery (LCA) description

• Branches from the ascending aorta and passes posterior to the pulmonary trunk.

Left coronary artery (LCA) areas supplied/branches

• Its branches include the anterior interventricular artery and the circumflex artery.

Anterior interventricular artery description

• Branches off the LCA and is located in the anterior interventricular sulcus.

• This artery is referred to clinically as the left anterior descending artery (LAD).

Anterior interventricular artery areas supplied/branches

• Supplies the anterior portion of the interventricular septum and the anterior walls of both ventricles.

Circumflex artery description

• Branches off the LCA :located in the coronary sulcus

Circumflex artery areas supplied/branches

• Supplies the left atrium and the posterior portion or the left ventricle.

Great cardiac vein description

• Located in the anterior interventricular sulcus, parallel to the anterior interventricular artery.

Great cardiac vein areas drained

• Anterior portions of the right and left ventncles.

Middle cardiac vein description

• Located in the posterior interventricular sulcus, parallel to the posterior interventricular artery.

Middle cardiac vein areas drained

• Posterior portions of the right and left ventricles

small cardiac vein description

• Located on the lateral right ventricle, parallel to the right marginal artery.

small cardiac vein areas drained

• Lateral right ventricle

Coronary sinus description

• Located in the coronary sulcus on the posterior surface of the heart; drains into the right atrium

Coronary sinus areas drained

• The entire heart; the great, middle and small cardiac veins all drain into the coronary sinus.

anterior cardiac veins description

• located on the anterior surface of the right atrium

anterior cardiac veins areas drained

• They drain directly into the right atrium

microscopic anatomy of cardiac muscle

• cardiac cells, crisscrossed by connective tissue fibers for strength. are arranged in spiral or figure-8-shaped bundles

when heart contracts, its internal chambers become smaller, forcing blood

into the large arteries leaving the heart.

arteries versus veins

arteries carry blood away from heart while veins carry towards heart

Systole versus diastole

Systole pumps blood into circulation (high pressure), while diastole allows the chambers to refill with blood (low pressure)