Anatomy Chapter 22

The 4 chambers of the heart:

1. Right Atrium 2. Right Ventricle 3. Left Atrium 4. Left Ventricle Each of these chambers played a role in the continuous process of blood circulation. Important to their function are valves, epithelium-lined dense connective tissue cusps that permit the passage of blood in one direction and prevent its back flow.

Functions of the Fibrous Skeleton:

1. Separates the atria and ventricles 2. Anchors the myocardium 3. Foundation for top set of valves 4. Does not conduct electricity, therefore top functional syncytium, so it prevents all of the heart chambers from beating at the same time

The heat consists of three distinctive layers:

1. The external epicardium(or visceral layer) 2. A middle myocardium 3. An internal endocardium

Right Atrium:

A chamber of the heart, at the top, it receives venous blood from the systemic circulation and the heart muscle itself. Three major vessels empty into the right atrium. The superior vena cavae, the inferior vena cavae, and the coronary sinus.

Coronary Sinus:

A large vein that lies in the posterior aspect of the coronary sulcus. The coronary sinus drains directly into the right atrium of the heart.

Fossa Ovalis or Oval Fossa:

An oval depression on the interatrial septum. It occupies the former location of the fetal foramen oval, which shunted blood from the right atrium to the left atrium during fetal life.

The two basic types of blood vessels are:

Arteries and Veins

Arteries carry blood:

Away from the heart

Veins carry blood:

Back to the heart

Chordae Tendineae:

Collagen fibers->stretchy strings. The chordae tendineae attach to the lower surface of cusps of the right AV valve and prevent the valve from everting and flipping into the atrium when the right ventricle is contracting.

Papillary Muscles:

Cone shaped. Anchor numerous thin strands of collagen fibers called chordae tendineae.

Systemic Circuit:

Consists of the chambers on the left side of the heart( left atrium and left ventricle) along with all the other named blood vessels. It carries blood to all the peripheral organs and tissues of the body. Blood that is high in oxygen(oxygenated) from the left side of the heart is pumped into the aorta, and then into smaller systemic arteries. Gas is exchanged with tissues from the body's smallest vessels and capillaries. Systemic veins then carry blood that is low in oxygen(deoxygenated) and high in carbon dioxide and waste products back to the heart. Most veins merge and drain into the superior and inferior vena cava, which drain blood into the right atrium, there, the blood enters the pulmonary circulation and the cycle repeats

Pulmonary Circuit:

Consists of the chambers on the right side of the heart(right atrium and right ventricle) as well as the pulmonary arteries and veins. This circulation conveys blood to the lungs via pulmonary arteries to reduce carbon dioxide and replenish oxygen levels in the blood before returning to the heart in pulmonary veins. Blood returns to the left side of the heart, where it enters the systemic circulation system.

Left Atrioventricular(AV) Valve or Bicuspid Valve:

Covers the atrioventricular opening. Oxygenated blood flows from the left atrium, through the left atrioventricular opening when the valve is open, into the left ventricle. The left AV valve is forced closed when the left ventricle begins to contract, preventing blood back flow into the atrium.

Right Atrioventricular Valve(AV) or Tricuspid Valve:

Covers the right atrioventricular opening.

Inferior Vena Cavae:

Empties into the right atrium. Drains blood from the heart wall.

Superior Vena Cavae:

Empties into the right atrium. Drains blood from the neck, head, upper limps and superior regions of the trunk.

Interventricular Septum:

Forms a thick wall between the right and left ventricles. The internal wall surface of each ventricle displays characteristic large, smooth, irregular muscular ridges called the trabeculae carneae.

Interatrial Septum:

Forms a thin wall between the left and right atria. The posterior atrial wall is smooth, but the auricle and anterior wall exhibit muscular ridges called pectinate muscles. The structural differences between the anterior and posterior walls occur because the two walls formed from separate structures during embryonic development. On the interatrial septum there is the fossa ovalis(or oval fossa).

Myocardium:

Heat muscle-multuple interlocking layers of cardiac muscle cells. Intercalated discs + desmosomes + gap junctions->2 separate electrical units. The myocardium is the middle layer of the heart wall and is composed of cardiac muscle tissue. It is the thickest of the three heart wall layers,it lies deep to the epicardium and superficial to the endocardium. The myocardial layer is where myocardial infarctions(heart attacks) occur. The arrangement of cardiac muscle in the heat wall permits the compression necessary to pump large volumes of blood out of the heart.

Trabeculae Carneae:

In both the right and left ventricles, more prominent in the left ventricle than in the right ventricle. In the left and right ventricles, irregular muscle folds or ridges in atrioventricular walls.

Cardiac Cycle:

Is the time from the start of one heart beat to the initiation of the next, about 8/10ths of a second for me. During a single cardiac cycle, all chambers within the heart experience alternate periods of contraction and relaxation.

Intercalated Discs:

Neighboring cardiac muscle cells in the walls of heart chambers have formed specialized cell-cell contacts called intercalated discs which electrically and mechanically link the cells together and permit the immediate passage of muscle impulses.

Aortic Semilunar Valve:

Part of the left ventricle, at the superior end of the ventricular cavity is the aortic semilunar valve. It marks the end of the left ventricle and the entrance to the aorta.

Parietal Layer:

Part of the pericardium, a subdivision of the serous pericardium. The parietal layer lines the inner surface of the fibrous pericardium.

Visceral Layer(Epicardium):

Part of the pericardium, a subdivision of the serous pericardium. The visceral layer or Epicardium, covers the outside of the heart, it is composed of a serous membranes and areolar connective tissue. As we age, more fat is deposited into the epicardium, and so this layer becomes thicker and more fatty.

The Pulmonary Trunk:

Part of the right ventricle. Divides shortly into right and left pulmonary arteries which carry deoxygenated blood to the lungs(blue).

The Pulmonary Semilunar Valves:

Part of the right ventricle. Marks the end of the right ventricle and the entrance into the pulmonary trunk.

Left Ventricle:

Pumps oxygenated blood into the body(systemic circuit). The left ventricle or wall is usual 3X thicker than the right ventricular wall. The left ventricle requires thicker walls to generate enough pressure to force the oxygenated blood that has returned to the heart from the lungs into the aorta and then through the entire systemic circulation(in contrast, the right ventricle only has to pump blood to the nearby lungs). Usually two large capillary muscles project from the ventricles inner wall and anchor the chord tendineae that attach the cusps of the left AV valve. At the superior end of the ventricular cavity is the aortic semilunar valve.

Right Ventricle:

Receives deoxygenated blood from the right atrium and pumps it to the lungs. The right ventricle typically has three cone-shaped, muscular projections called papillary muscles.

Left Atrium:

Receives oxygen-rich blood from the lungs. Once gas exchange occurs in the lungs, oxygenated blood travels through the pulmonary veins to the left atrium. The smooth posterior wall of the left atrium contains openings for approximately 4 pulmonary veins(red, O2). Sometimes two of these vessels fuse prior to reaching the left atria, thus decreasing the number of openings through the atrial wall. Like the right atrium, the left atrium also has pectinate muscles along its anterior wall as well as an auricle.

Left Atrioventricular Opening:

Separates the left atrium form the left ventricle, and is covered by the left atrioventricular(AV) valve or the bicuspid valve.

Right Atrioventricular Opening:

Separates the right atrium from the right ventricle. This opening is covered by a right atrioventricular valve(AV) or tricuspid valve. Deoxygenated venous blood flows from the right atrium through the right atrioventricular opening when the valve is open, into the right ventricle. The right AV valve is forced closed when the right ventricle begins to contract, preventing blood from flowing back into the right atrium.

Pericardium:

Serous membrane-parietal pericardium. Dense irregular fibrous tissue-> pericardial cavity-> 10-20mL. Glea-> anchors heart-> heart cannot overfill->serous fluid->reduce heart. The heart is contained within the pericardium, a fibrous sac and serious lining, The pericardium restricts the hearts movements so that it doesn't bounce and move about in the thoracic cavity, and prevents the heart from overfilling with blood. The pericardium is composed to two parts, the fibrous pericardium and the serous pericardium.

Conducting System:

Signals chambers to contact in a proper sequence, sets heart rate. The hear exhibits autorhythmicity, meaning that the heart itself(not external nerves) is responsible for initiating the heart beat, so its a electrical signal and doesn't need a message from the brain to work. Certain cardiac muscle cells are specialized to initiate and conduct muscle impulses to the contractile muscle cells of the myocardium. Collectively, these specialized cells are called the heart's conducting system.

Endocardium:

Simple squamous->smooth surface, therefore decreases friction. White sheet like lining. The internal surface of the heart and the external surfaces of the heart valves are covered by endocardium. It is composed of simple squamous epithelium called endothelium, and a layer of areolar connective tissue.

What two things divide the heart into two separate pumps?

The Interatrial Septum and the Interventricular Septum.

Systole:

The contraction of a heat chamber, wringing-emptying. During this period, the contraction of the myocardium forces blood either into another chamber(from atrium to ventricle) or into a blood vessel(from ventricle into the attached large artery).

Firbous Skeleton:

The fibrous skeleton of the heart is located between the atria and the ventricles, and is formed from dense regular connective tissue.

Cornoary circulation:

The heart's blood vessel

Sinoatrial (SA) Node(pacemaker):

The heartbeats initialized by these specialized cardiac muscle cells, which are located in the posterior wall of the atrium, adjacent to the entrance of the superior vena cava. The cells of the SA node act as the pacemaker, the rhythmic venter that establishes the pace for cardiac activity. Under the influence of parasympathetic innervation, SA node cells initiate 70 to 80 times per minute.

Serous Pericardium:

The inner portion of the pericardium, its a double layered serous membrane. The serous pericardium may be subdivided into two parts, a parietal layer and a visceral layer. These two layers reflect(fold back) along the great vessels, where these two layers become continuous with one another.

Aorta:

The largest systemic artery in the body

Atrioventricular (AV) Bundle or the bundle of His:

The opening in the fibrous skeleton that allows the AV nod4e to communicate with the next part of the conduction system is the AV bundle. This bundle receives the muscle impulse from the AV node and extends into the inter ventricular system before dividing into the four left and right bundles. These bundles conduct the impost to conduction fibers called purkinje fibers.

Fibrous Pericardium:

The outer portion of the pericardium, is a tough dense connective tissue layer called the fibrous pericardium, this layer is attached to both the diaphragm and the base of the great vessels.

The cardiovascular system consists of two circulations:

The pulmonary circulation and The systemic circulation

Diastole:

The relaxation phase of a heart chamber, filling with blood. During this period between contraction phases, the myocardium of each chamber relaxes and the chamber fills with blood.

Parietal Cavity:

The this space between the parietal and visceral layers of the serous pericardium is the parietal cavity, into which serous fluid is secreted to lubricate the serous membranes and facilitate the almost frictionless, continuous movement of the heart when it beats.

Perkinje Fibers:

There are 5, they are conduction fibers that begin with the apex of the heat and extend through the walls of the ventricles. Perkinje fibers are larger than other cardiac muscle cells. Muscle impulse conduction along the purkinje fibers is extremely rapid, consistent with the large size of the cells and the impulse spreads immediately throughout the ventricular myocardium.

Desmosomes:

There are numerous desmosomes within the intercalated discs that prevent cardiac muscle cells form pulling apart. So, cardiac muscle cells function as a single coordinated unit; the precisely timed stimulation and respond by cardiac muscle cells of both the atria and ventricle are dependent upon these structural features.

The function of the Pulmonary Semilunar Valve and the Aortic Semilunar Valve:

They open to allow blood out of ventricles and then close so blood cannot flow backward.

Gap Junctions:

Within the intercalated discs. The gap junctions increase the flow of ions between the cells as the muscle impulse moves along the sacrolemma. The gap junctions of intercalated discs provide a low-resistance pathway across the membranes of adjoining cardiac muscle cells, allowing the unrestricted passage of ion required for the synchronous beating of cardiac muscle cells.

Atrioventricular (AV) Node:

Without this you're not okay. The muscle impulse travels form the SA node to the AV node. The AV node is located in the flow of the rich atrium, between the right AV valve and the opening for the coronary sinus. The AV node normally slows conduction of the impulse as it travels from the atria to the ventricle, providing a delay between activation and contraction of ventricles. 40-60 beats per minute.

As the center of the cardiovascular system, the __________ connects blood vessels that transport between the _______ and all _________ __________

heart, heart, body tissue