Chapter 19: The Cardiovascular System: The Heart

**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.