Chapter 19: The Cardiovascular System: The Heart

septum

septum

(plural = septa) refers to a wall or partition that divides the heart into chambers.

posterior interventricular sulcus

is visible on the posterior surface of the heart.

anterior interventricular sulcus

is visible on the anterior surface of the heart

coronary sulcus

is located between the atria and ventricles.

sulcus

Also prominent is a series of fat-filled grooves

auricle

There is a superficial leaf- like extension of the atria near the superior surface of the heart, one on each side

mesothelium

In the case of the heart, it is not a microscopic layer but rather a macroscopic layer, consisting of a simple squamous epithelium called a

epicardium

which is fused to the heart and is part of the heart wall.

pericardium or pericardial sac

The membrane that directly surrounds the heart and defines the pericardial cavity is called the

superior vena cava and the inferior vena cava

which return blood to the right atrium.

pulmonary trunk

which leads toward the lungs and bifurcates into the left and right pulmonary arteries.

systemic circuit

transports oxygenated blood to virtually all of the tissues of the body and returns relatively deoxygenated blood and carbon dioxide to the heart to be sent back to the pulmonary circulation.

pulmonary circuit

transports blood to and from the lungs, where it picks up oxygen and delivers carbon dioxide for exhalation.

one atrium and one ventricle

The human heart consists of four chambers: The left side and the right side each have

Cardiology

is the study of the heart, and cardiologists are the physicians who deal primarily with the heart.

pericardial cavity

Within the mediastinum, the heart is separated from the other mediastinal structures by a tough membrane known as the pericardium, or pericardial sac, and sits in its own space called the

cardiac notch

The slight deviation of the apex to the left is reflected in a depression in the medial surface of the inferior lobe of the left lung, called the

hypertrophic cardiomyopathy

Enlarged hearts are not always a result of exercise; they can result from pathologies, such as

Oxygen

________ from the lungs is brought to the heart, and every other organ, attached to the hemoglobin molecules within the erythrocytes.

Cardiac output

________ (CO) is a measurement of the amount of blood pumped by each ventricle in one minute.

venosus

The sinus ________ develops into the posterior portion of the right atrium, the SA node, and the coronary sinus.

Cardiology

________ is the study of the heart, and cardiologists are the physicians who deal primarily with the heart.

Normal cardiac rhythm

________ is established by the sinoatrial (SA) node, a specialized clump of myocardial conducting cells located in the superior and posterior walls of the right atrium in close proximity to the orifice of the superior vena cava.

Afterload

________ refers to the tension that the ventricles must develop to pump blood effectively against the resistance in the vascular system.

bulbus cordis

The ________ develops into the right ventricle.

truncus arteriosus

The ________ will eventually divide and give rise to the ascending aorta and pulmonary trunk.

Purkinje fibers

The ________ are additional myocardial conductive fibers that spread the impulse to the myocardial contractile cells in the ventricles.

period of relaxation

The ________ that occurs as the chambers fill with blood is called diastole.

aortic semilunar

At the base of the aorta is the ________ valve, or the aortic valve, which prevents backflow from the aorta.

membrane

The ________ that directly surrounds the heart and defines the pericardial cavity is called the pericardium or pericardial sac.

right atrium

The ________ serves as the receiving chamber for blood returning to the heart from the systemic circulation.

cardiogenic area

The ________ begins to form two strands called the cardiogenic cords.

superior vena cava

The capillaries will ultimately unite to form venules, joining to form ever- larger veins, eventually flowing into the two major systemic veins, the ________ and the inferior vena cava, which return blood to the right atrium.

systemic circuit transports

The ________ oxygenated blood to virtually all of the tissues of the body and returns relatively deoxygenated blood and carbon dioxide to the heart to be sent back to the pulmonary circulation.

right ventricle

The marginal arteries supply blood to the superficial portions of the ________.

second major branch

The larger anterior interventricular artery, also known as the left anterior descending artery (LAD), is the ________ arising from the left coronary artery.

right ventricle pumps

The ________ deoxygenated blood into the pulmonary trunk, which leads toward the lungs and bifurcates into the left and right pulmonary arteries.

human heart

The ________ is located within the thoracic cavity, medially between the lungs in the space known as the mediastinum.

pulmonary circuit transports

The ________ blood to and from the lungs, where it picks up oxygen and delivers carbon dioxide for exhalation.

posterior surface

On the ________ of the heart, the right coronary artery gives rise to the posterior interventricular artery, also known as the posterior descending artery.

A typical heart is approximately the size of your fist

12 cm (5 in) in length, 8 cm (3.5 in) wide, and 6 cm (2.5 in) in thickness

The human heart consists of four chambers

The left side and the right side each have one atrium and one ventricle

The more delicate serous pericardium consists of two layers

the parietal pericardium, which is fused to the fibrous pericardium, and an inner visceral pericardium, or epicardium, which is fused to the heart and is part of the heart wall

There is a superficial leaf

like extension of the atria near the superior surface of the heart, one on each side, called an auricle, a name that means "ear-like" because its shape resembles the external ear of a human

interatrial septum

Located between the two atria

septum primum

a flap of tissue

interventricular septum

Between the two ventricles is a second septum

atrioventricular septum

The septum between the atria and ventricles

valve

a specialized structure that ensures one-way flow of blood.

atrioventricular valves

The valves between the atria and ventricles

semilunar valves

The valves at the openings that lead to the pulmonary trunk and aorta

cardiac skeleton

Since these openings and valves structurally weaken the atrioventricular septum, the remaining tissue is heavily reinforced with dense connective tissue

coronary sinus

The two major systemic veins, the superior and inferior venae cavae, and the large coronary vein

pectinate muscles

While the bulk of the internal surface of the right atrium is smooth, the depression of the fossa ovalis is medial, and the anterior surface demonstrates prominent ridges of muscle

chordae tendineae

Each flap of the valve is attached to strong strands of connective tissue

papillary muscle

extends from the inferior ventricular surface.

trabeculae carneae

ridges of cardiac muscle covered by endocardium.

moderator band

In addition to these muscular ridges, a band of cardiac muscle, also covered by endocardium

pulmonary valve

it is also known as the pulmonic valve or the right semilunar valve.

aortic valve

which prevents backflow from the aorta.

Coronary arteries

supply blood to the myocardium and other components of the heart.

epicardial coronary arteries

Coronary vessel branches that remain on the surface of the artery and follow the sulci are called

circumflex artery

arises from the left coronary artery and follows the coronary sulcus to the left.

anterior interventricular artery

The larger ___ also known as the left anterior descending artery (LAD), is the second major branch arising from the left coronary artery.

anastomosis

An __ is an area where vessels unite to form interconnections that normally allow blood to circulate to a region even if there may be partial blockage in another branch.

marginal arteries

The__ supply blood to the superficial portions of the right ventricle.

posterior interventricular artery

also known as the posterior descending artery.

Coronary veins

drain the heart and generally parallel the large surface arteries.

great cardiac vein

can be seen initially on the surface of the heart following the interventricular sulcus, but it eventually flows along the coronary sulcus into the coronary sinus on the posterior surface.

posterior cardiac vein

parallels and drains the areas supplied by the marginal artery branch of the circumflex artery.

middle cardiac vein

middle cardiac vein parallels and drains the areas supplied by the posterior interventricular artery.

small cardiac vein

parallels the right coronary artery and drains the blood from the posterior surfaces of the right atrium and ventricle.

anterior cardiac veins

parallel the small cardiac arteries and drain the anterior surface of the right ventricle.

intercalated disc

which helps support the synchronized contraction of the muscle.

internodal pathways

This impulse spreads from its initiation in the SA node throughout the atria through specialized

Bachmann’s bundle

or the interatrial band that conducts the impulse directly from the right atrium to the left atrium.

Atrioventricular (AV) Node

is a second clump of specialized myocardial conductive cells, located in the inferior portion of the right atrium within the atrioventricular septum.

Purkinje fibers

are additional myocardial conductive fibers that spread the impulse to the myocardial contractile cells in the ventricles.

electrocardiogram (ECG)

This tracing of the electrical signal is

cardiac cycle

The period of time that begins with contraction of the atria and ends with ventricular relaxation is known as the

systole

The period of contraction that the heart undergoes while it pumps blood into circulation is called

diastole

The period of relaxation that occurs as the chambers fill with blood is called

Cardiac output (CO)

is a measurement of the amount of blood pumped by each ventricle in one minute.

cardiac reserve

The difference between maximum and resting CO is known as

autonomic tone

During rest, both centers provide slight stimulation to the heart, contributing to

cardiac plexus

near the base of the heart.

cardiac reflexes

Collectively, these inputs normally enable the cardiovascular centers to regulate heart function precisely

baroreceptor reflex

The cardiac centers monitor baroreceptor firing to maintain cardiac homeostasis, a mechanism called the

atrial reflex or Bainbridge reflex

associated with varying rates of blood flow to the atria.

Afterload

refers to the tension that the ventricles must develop to pump blood effectively against the resistance in the vascular system.

heart bulge

appears on the anterior surface of the embryo.

mesoderm

The heart forms from an embryonic tissue

cardiogenic area

The heart begins to develop near the head of the embryo in a region

cardiogenic cords

The cardiogenic area begins to form two strands called the

primitive heart tube

The two tubes migrate together and fuse to form a single

truncus arteriosus

will eventually divide and give rise to the ascending aorta and pulmonary trunk.

bulbus cordis

develops into the right ventricle.

primitive ventricle

forms the left ventricle.

primitive atrium

becomes the anterior portions of both the right and left atria, and the two auricles.

sinus venosus

develops into the posterior portion of the right atrium, the SA node, and the coronary sinus.