Lab 17 Flashcards
The cardiovascular system transports
oxygen, nutrients, wastes, other solutes, and cells throughout the body.
the cardiovascular system with the pump that drives it—
the heart.
The heart is a remarkable organ, tirelessly beating more than
100,000 times per day to pump more than 8,000 liters of blood around the body
the heart is surrounded by a double-layered membrane called the
pericardium (pehr-ee-KAR-dee-um).
the heart is located in the
mediastinum and is on average about the size of a fist
Its apex is its _______ and its base is its ________
pointy inferior tip, and its base is its flattened posterior side
The heart is composed of
four chambers—the small, superior right and left atria and the larger, inferior right and left ventricles.
The chambers are separated visually by grooves on the heart’s surface:
The atrioventricular sulcus (ay-tree-oh-ven-TRIK-yoo-lur) is between the atria and ventricles, and the interventricular sulcus is between the two ventricles.
The outer most layer of the pericardium, called the
fibrous pericardium, anchors the heart to surrounding structures.
fibrous pericardium is made of
dense irregular collagenous connective tissue that is not very distensible, which helps to prevent the heart from overfilling.
The inner layer, called the
serous pericardium, is itself composed of two layers.
two layers of the serous pericardium
parietal pericardium; visceral pericardium (epicardium)
parietal pericardium
functionally fused to the fibrous pericardium. Notice that at the edges of the heart, the parietal pericardium folds over on itself to attach to the heart muscle and form the inner layer of the serous membrane called the visceral pericardium, also known as the epicardium.
epicardium
visceral pericardium
Between the parietal and visceral layers we find a thin layer of
serous fluid that occupies a narrow potential space called the pericardial cavity.
The fluid within the pericardial cavity helps the heart to
beat without friction.
The heart itself is an organ that consists of three tissue layers:
Epicardium; Myocardium; Endocardium
- Epicardium.
The epicardium (ep-ih-KAR-dee-um) or visceral pericardium is considered the outermost layer of the heart wall. It consists of a layer of simple squamous epithelial tissue and loose connective tissue
Myocardium
.2. Myocardium. The middle myocardium (my-oh-KAR-dee-um) is the actual muscle of the heart. It consists of cardiac muscle tissue and its fibrous skeleton.
Endocardium
- Endocardium. The innermost endocardium is a type of simple squamous epithelium called endothelium. It is continuous with the endothelium lining all blood vessels in the body.
The atria receive blood from
veins,
veins
which are vessels bringing blood to the heart.
The ventricles eject blood into
arteries,
arteries,
which carry blood away from the heart.
The vessels entering and exiting the heart are the largest in the
body and so are called great vessels.
There are four sets of great vessels including the following:
- Superior and inferior venae cavae; pulmonary trunk; pulmonary veins; aorta
- Superior and inferior venae cavae.
The superior vena cava (VEE-nah KAY-vah) is a large vein that drains deoxygenated blood from structures located, in general, above the diaphragm, while the inferior vena cava drains structures located, in general, below the diaphragm. Both empty into the right atrium. These veins drain a group of blood vessels collectively called the systemic circuit, in which oxygen and nutrients are delivered to cells by systemic arteries and deoxygenated blood is returned to the heart by systemic veins.
- Pulmonary trunk.
The pulmonary trunk is a large artery that exits from the right ventricle. Shortly after it forms, it splits into right and left pulmonary arteries, which deliver deoxygenated blood to the lungs through a series of vessels collectively called the pulmonary circuit. Within the pulmonary circuit, gases are exchanged, and the blood becomes oxygenated.
- Pulmonary veins.
The pulmonary veins are the portion of the pulmonary circuit that brings oxygenated blood back to the heart. There are generally four pulmonary veins, and they empty into the left atrium.
- Aorta.
The large aorta (ay-OHR-tah) is the first and largest artery of the systemic circuit. It stems from the left ventricle, after which it branches repeatedly to deliver oxygenated blood to the body’s cells.
The other set of blood vessels visible on the external surface of the heart are the vessels collectively called the
coronary circulation (KOHR-oh-nehr-ee).
The coronary arteries branch off the base of the aorta and bring oxygenated blood to
the cells of the myocardium.
The myocardium is drained by a set of
cardiac veins.
The first coronary artery, the right coronary artery, travels along the
right side of the atrioventricular sulcus. It branches into the right marginal artery, which serves the lateral part of the right atrium and right ventricle, and the posterior interventricular artery, which serves the posterior heart.
The other coronary artery is the
left coronary artery, which branches shortly after it forms into the anterior inter-ventricular artery (also known as the left anterior descending artery), which travels along the interventricular sulcus to supply the anterior heart. Its second branch is the circumflex artery (SIR-kum-flex),
circumflex artery (SIR-kum-flex),
which travels in the left side of the atrioventricular sulcus to supply the left atrium and posterior left ventricle.
When a coronary artery is blocked, the reduced blood flow to the myocardium causes a situation known as .
myocardial ischemia.
Severe blockage may result in
hypoxic injury and death to the tissue, a condition termed myocardial infarction (commonly called a heart attack).
The anatomy of the cardiac veins often varies from person to person, but the following three main veins generally are present:
small cardiac vein; middle cardiac vein; great cardiac vein
(1) the small cardiac vein,
which drains the right inferolateral heart
; (2) the middle cardiac vein,
which drains the posterior heart;
and (3) the great cardiac vein,
which drains most of the left side of the heart.
All three veins drain into
the large coronary sinus located on the posterior right atrium.
The coronary sinus drains into
the right atrium.
the atria and ventricles are divided by muscular walls
called septa.
In between the atria is a thin wall called the
interatrial septum (in-ter-AY-tree-uhl).
interatrial septum (in-ter-AY-tree-uhl).
This wall has a small dent in it called the fossa ovalis (FAWS-ah oh-VAL-is),
fossa ovalis (FAWS-ah oh-VAL-is),
which is a remnant of a hole, called the foramen ovale, that was present during fetal life.
The much thicker interventricular septum separates
the two ventricles.
the heart’s four chambers
right atrium; right ventricle; left atrium; left ventricle
.1. Right atrium.
The right atrium (AY-tree-um) is the superior right chamber. It receives deoxygenated blood from the body’s main veins—the superior vena cava, the inferior vena cava, and the coronary sinus—the openings for which we find on the right atrium’s posterior side. Externally, it has a large pouch called the right auricle (OHR-ih-kuhl) that allows the right atrium to expand and fill with more blood. Internally, the anterior surface of the right atrium is rough due to muscular ridges called pectinate muscles (PEK-tin-et)
Right ventricle.
The right ventricle is a wide, crescent-shaped, thin-walled chamber inferior to the right atrium, from which it receives deoxygenated blood. It ejects blood into a vessel called the pulmonary trunk. Internally, its surface contains ridge-like protrusions of cardiac muscle called trabeculae carneae (trah-BEK-yoo-lee kar-NEE-ee).
- Left atrium.
The superior left chamber is the left atrium. It receives oxygenated blood returning from the pulmonary circuit via four pulmonary veins. Externally, it has a left auricle, although it is much smaller than the right auricle. Internally, its surface is mostly smooth and it lacks pectinate muscles.
- Left ventricle.
The left ventricle is a thick, long, circular chamber that receives oxygenated blood from the left atrium and pumps it into the aorta.; the left ventricle is considerably thicker than the right ventricle. This reflects the fact that the pressure is much higher in the systemic circuit than it is in the pulmonary circuit. The higher pressure requires the left ventricle to pump harder, and so it has greater muscle mass and is thicker. Like the right ventricle, trabeculae carneae line the left ventricle’s internal surface. To ensure that blood in the heart flows only in a single direction, we have structures called valves
two types of valves in the heart
atrioventricular and semilunar
There are two types of valves in the heart. First are the valves between the atria and ventricles, which are called
atrioventricular
the two atrioventricular valves
mitral valve and tricuspid valve
The three-cusped tricuspid valve is between the
right atrium and right ventricle,
and the two-cusped mitral (MY-trul) or bicuspid valve is between the
left atrium and left ventricle.
Each cusp of the atrioventricular valves is attached to
collagenous “strings” called chordae tendineae (KOHR-dee tin-din-EE-ee), which are themselves attached to muscles within the ventricular wall called papillary muscles.
When the ventricles contract, the papillary muscles pull the chordae tendineae taut, which puts tension on the cusps and prevents them from
everting into the atria, a condition called prolapse
.Second are the valves between the ventricles and their arteries,
which are called semilunar valves.
the two semilunar valves are
aortic valve and pulmonary valve
The pulmonary valve sits between the
right ventricle and the pulmonary trunk,
and the aortic valve sits between the
left ventricle and the aorta. Note that there are no chordae tendineae or papillary muscles attached to the semilunar valves.
General structures of the heart
Mediastinumb. Apex of the heartc. Base of the heartd. Atrioventricular sulcuse. Interventricular sulcusf. Pericardium (1) Fibrous pericardium (2) Serous pericardium (a) Parietal pericardium (b) Visceral pericardium (epicardium) (c) Pericardial cavityg. Myocardiumh. Endocardium
Great vesselsa.
Superior vena cavab. Inferior vena cavac. Pulmonary trunk d. Right and left pulmonary arteriese. Pulmonary veinsf. Aorta
- Coronary arteriesa.
Right coronary arteryb. Right marginal arteryc. Posterior interventricular artery d. Left coronary arterye. Anterior interventricular arteryf. Circumflex artery
Cardiac veinsa.
Small cardiac veinb. Middle cardiac veinc. Great cardiac veind. Coronary sinus
- Interatrial septuma.
Fossa ovalis
- Interventricular septum
- Interventricular septum - that’s all there is
- Right atriuma.
Opening of the superior vena cavab. Opening of the inferior vena cavac. Opening of the coronary sinus d. Right auriclee. Pectinate muscles
- Right ventricle
a. Trabeculae carneae
- Left atriuma.
Left auricleb. Openings of the pulmonary veins
- Left ventriclea.
Trabeculae carneae
- Atrioventricular valves
a. Tricuspid valveb. Mitral valvec. Chordae tendineaed. Papillary muscles
- Semilunar valvesa.
Pulmonary valveb. Aortic valve
Cardiac muscle tissue is
striated like skeletal muscle tissue but otherwise is quite different
Important structural differences
:■■Cells of cardiac muscle, known as cardiac myocytes, are shorter, wider, and branched, whereas skeletal muscle fibers are long, thin, and unbranched. ■■Cardiac muscle cells typically are uninucleate, although some have multiple nuclei. The nucleus is generally located near the center of the cell.■■These cells contain specialized adaptations called intercalated discs (in-TUR-kuh-layt-ed) that appear as dark lines parallel to the striations. These discs contain desmosomes and gap junctions that hold adjacent cardiac cells tightly together to allow the cells to communicate chemically and electrically.
This adaptation is important to the heart’s function: For a heart contraction to occur,
all of the cells of the atria must contract simultaneously as a unit, and then all of the cells of the ventricles must contract simultaneously as a unit. Contrast this with skeletal muscles, in which the number of muscle fibers that contract is proportional to the strength of the contraction.
cardiac myocytes
cardiac cell muscles
uninucleate
single nucleus
intercalated discs
contain desmosomes and gap junctions that hold adjacent cardiac cells tightly together to allow the cells to communicate chemically and electrically.
