Chapter 22 Objective

Front 1

Describe the three major layers of the heart wall and how they relate to the pericardium.

Back 1

• Endocardium – (inner heart) – membrane lining the heart’s inner wall.
• Myocardium – the middle, thickest layer of the heart; made up of thick, stong muscles.
• Epicardium – the thin outer layer of the cardiac wall (also called the visceral layer of the serous pericardium).
• Pericardium – (pericardial sac) – a sac that surrounds and protects the heart.
 Epicardium portion of the heart wall also makes up the pericardium’s visceral layer and adheres to the heart’s surface.
 Parietal layer – the inner serous pericardium.
 Pericardial space – space between the visceral and parietal layers. It houses a small amount of fluid, pericardial fluid, that acts as a lubricant and reduces friction between the layers as the heart contracts and relaxes.
 Fibrous pericardium – (outmost layer) – anchors the heart in the mediastinum and prevents overfilling.

Front 2

Identify the chambers of the heart on an anatomical model, including the major vessels that enter and exit each chamber.

Back 2

• Left atrium – receives from the vena cava.
• Left ventricle – empties into the pulmonary arteries.
• Right atrium – receives from the pulmonary veins.
• Right ventricle – empties into the aorta.

Front 3

Define and describe the function of the atrioventricular valves, semilunar valves, chordae tendineae, and papillary muscles.

Back 3

• Atrioventricular valves – (AV) – the valves that lie between the atria and ventricles. The valve between the right atrium and right ventricle is the tricuspid valve, because it is formed of three flaps of tissue. The valve between the left atria and ventricle is the mitral valve (bicuspid valve).
 Blood flows from the atria to the ventricles thru open AV valves when pressure in the ventricles is lower than pressure in the atria.
• Semilunar valves – three crescent-shaped (half-moon) cusps that form the valve in which the ventricles empty.
o Pulmonary semilunar valve – separates the right ventricle from the pulmonary artery and is called the pulmonic valve.
o Aortic valve – separates the left ventricle from the aorta.
 Increased ventricle pressure, during ventricular contraction, opens the semilunar valves. They prevent backflow from their respective arteries into their ventricles.
• Chordae Tendineae – tendon-like strands that attach the AV valve flaps and anchor to papilla

Front 4

Trace the path of blood through both sides of the heart, using correct terminology.

Back 4

• The right atrium receives deoxygenated blood from the superior and inferior vena cava and the coronary sinus. Blood then passes thru the tricuspid valve into the right ventricle. It moves on thru the pulmonic valve during ventricular contraction to enter the pulmonary artery and then the lungs, where it receives oxygen. Oxygenated blood then returns to the left atrium via the four pulmonary veins. It travels thru the mitral valve and into the left ventricle. During ventricular contraction, the blood from this chamber exits thru the aortic valve into the aorta and out to the systemic circulation.

Front 5

Identify the coronary arteries supplying the myocardium, specifying the location of each and the areas supplied; define collateral circulation.

Back 5

• Two coronary arteries (right and left) branch off the ascending aorta to provide blood to the heart muscle. Their openings (orifices) lie behind two cusps of the aortic valve. They receive their blood supply during ventricular relaxation, when the valves are closed. The LCA and RCA divide into smaller branches that penetrate the myocardium to supply the heart tissue with oxygen and nourishment.

o LCA- passes along the left atrium and divides into 2 branches: the anterior interventricular branch (left anterior descending artery LAD) and the let circumflex artery (LCX). The LAD descends along the anterior intraventricular groove to provide blood to most of the ventricular septum and the anterior portion of the left ventricle. It also provides blood to the anterior papillary muscles, the apex of the left ventricle and the right and left bundle branches. The LCX extends around the left side of the heart, along the groove between the left atrium and the left ventricle, to supply blood to the left atr

Front 6

Compare and contrast the structure and function of arteries, capillaries, and veins.

Back 6

Arteries Elastic and smooth (involuntary) muscular tubes. Also known as “resistance vessels” that can support high pressures and hold large volumes of blood. Carries oxygenated blood to the body cells.

*Pulmonary arteries carry deoxygenated blood from the heart into the lungs*

Capillaries Smallest vessels; so small that the tiny red blood cells must pass through them in single file. Contains relatively high osmotic pressure of albumin. Blood flows slowly, allowing time for oxygen and nutrients to leave the blood vessels and to enter body tissues, and for blood containing cellular waste to enter the capillary. Exchanges thru the capillary wall are due to diffusion and filtration.

Veins Veins lie between skeletal muscles and do not pulsate. They contain venous valves that contribute to the efficient venous blood flow and permit blood to flow in one direction only. After the exchange occurs in the capillaries, blood starts back towards the heart via the veins. Superior vena cava (SVC) returns

Front 7

Describe the path of an electrical impulse through the conduction system of the heart. Describe the purpose of this electrical activity.

Back 7

• Conduction System of the Heart:
 SA (sinoatrial) node – pacemaker
 AV (atrioventricular) node
 Bundle of His (AV bundle)
 Right and left bundle branches
 Purkinje fibers of muscles of ventricles



• Special bundles of unique tissue in the heart transmit and coordinate electrical impulses to stimulate the heart to beat. The 1st of these bundles is embedded in the wall of the right atrium at the junction of the SVC; sinoatrial (SA) node; which is considered the heart’s “pacemaker”. The SA node sets the pace, and the rest of the heart follows; SA node causes the atria to contract. The AV node receives that message from the SA node and holds it until the atria have contracted and emptied blood into the ventricles. When the ventricles are ready to receive the impulse, the AV node transmits it thru the bundle of His (AV bundle) and down the interventricular septum to the right and left bundle branches. From there, the fibers penetrate the ventricular muscle and terminate

Front 8

Explain the events associated with S1 and S2 heart sounds, indicating where each of these sounds is best heard.

Back 8

• The first normal heart sound (S1) is called the “lub” and is produced by the closure of the AV valves when the ventricles contract. The second heart sound (S2) is called the “dub” and is produced by the closure of the semilunar valves when the ventricles relax.
• S1 occurs at the beginning of systole and can be heard over all the pericardium but usually the loudest at the apex of the heart.
• S2 occurs at the beginning of diastole and can be heard at the base of the heart.

Front 9

Describe cardiac output, including the factors involved in its regulation.

Back 9

• Cardiac output (CO) - the amount of blood that the ventricles pump out in 1 minute. In a resting adult, normal CO is between 4-6 L. The stroke volume (SV) is the volume of blood ejected with each heartbeat. When calculating the CO, multiply the SV by the number of beats per minute or heart rate (HR).

• The heart can alter its CO to adapt to the body’s metabolic needs. The autonomic nervous system can influence HR; for example, during a dangerous situation, the heart rate increases. Factors of preload and afterload can affect SV.

Front 10

Differentiate between systolic and diastolic blood pressure, defining each term.

Back 10

• Systolic B/P – the pressure of the blood against the walls of the arteries when the heart beats. *The top number of a blood pressure*
• Diastolic B/P – the pressure of the blood against the arterial walls when the heart is at rest between beats. *The bottom number of a blood pressure*