Chapter 13

I. Aids to Understanding Words

brady-: Slow

Ex: Bradycardia: Abnormally slow heartbeat.

diastol- : Dilation

Ex: Diastolic Pressure: Blood pressured when the ventricle of the heart is relaxed.

-gram: Something written.

Ex: Electrocardiogram: Recording of the electrical changes in myocardium during a cardiac cycle.

papill- : Nipple

Ex: Papillary muscle: Small mound of muscle projecting into a ventricle of the heart.

syn- : Together

Synotium: Mass of merging cells that act together.

systol- : Contraction

Systolic Pressure: Blood pressure resulting from a single ventricular contraction.

tachy- : Rapid

Tachycardia: Abnormally fast heartbeat.

13.1 Introduction

What is the function of the cardiovascular system?

The cardiovascular system sends oxygen poor blood cells to the lungs to get more oxygen through the pulmonary circuit, and sends oxygen rich blood to all body cells and removes waste through the systematic circuit.

13.2 Structures of Heart

A. Describe precise location of the heart.

Heart is bordered laterally by the lungs, posteriorly by the ventral column, and anteriorly by the sternum. Base of the heart attaches to large blood vessels, beneath the second rib.

B. Answer:

1. The heart is enclosed by a double layer sac called the pericardium.

2. What is the function of the fluid in the pericardial space?

The serous fluid reduces friction between pericardial membranes as heart moves within.

3. Describe the pathological events of pericarditis.

The pericarditis is the inflammation of the pericardium that occurs because of a bacterial infection or viral infection. The condition interferes with heart movements.

C2. Pericardial Activity: Found between the parietal and visceral serous layers of pericardium. It contains small volumes of serous fluid.

Parietal Pericardium: Covers the inner surface of fibrous pericardium.

Fibrous Pericardium: Outer layer that consists of fibrous bag. It’s composed of dense connective tissue.

Endocardium: Inner layer of the wall of the heart. It consists of epithelium and underlying connective tissue that contains elastic and collagen fibers.

Myocardium: Thick middle layer of wall of the heart. Consists of cardiac muscle tissue that pumps blood our of heart chambers.

Epicardium: Protects the heart by reducing friction.

D1. List the chambers of the heart.

Atria: Upper chamber that have thin walls and receive the blood that returns to the heart.

Ventricles: Lower chambers. Receives blood from atria and contract to force blood out of the heart into arteries.

Four Chambers: Right atrium, right ventricle, left atrium, and left ventricle.

D3. What vessels take blood to the right atrium?

The right atrium gets blood from two large veins, superior vena cava, and inferior vena cava.

D4. What vessels take blood to the left atrium?

Left atrium receives blood from the lungs with four pulmonary veins. Two from the right and two from the left.

F. What is the mitral valve prolapse?

Mtrol Valve Prolapse (MVP) is a condition which one or both of the cusps of the mitral valve strech and bulge into the left atrium during the ventricle contraction. Valves continue to function, but blood regurgitation occurs in left atrium,

G. The cells of the heart are supplied with blood via the lungs.

H. What happens when the heart muscle is deprived of oxygen?

When the heart is low on oxygen, the heart sends low oxygenated blood to the right atrium to the vena cava to the coronary sinuses. The blood goes through the tricuspid valve and enters the right ventricle. The right ventricle wall contracts, closing the tricuspid valve, and let blood pass through the pulmonary arteries. In turn, the blood is sent to the capillaries that are associated with the alveoli. Gas exchange results in oxygenated blood which is returned to the heart.

I. Compare myocardial infarction and angina pectoris.

Angina pectoris feels like heavyp ressure with tightening or squeezing in the chest. Felt behind sternum and anterior upper thorax. Myocardial infarction (MI), also known as a heart attack, is a blood clot that obstructs a coronary artery. This blood cot kills tissue within that part of the heart.

13.3 Heart Action

A1. What events make up a cardiac cycle?

The atria contracts and the ventricle relaxes. Then the ventricle contracts and the atria relaxes. Then both atria and ventricle both relax for a brief interval. The repetition of these vents make up the cardiac cycle.

A2. What produces the heart sounds heard with a stethoscope?

The vibration in the heart tissues with the valve closing. A heartbeat is said to sound like “lubb-dupp”. The “lubb” occures during ventricle systole. The “dupp” occurs during ventricle diastole.

B. Describe the characteristics of cardiac muscle fibers.

Functional synotium is mass of merging cells acting as a unit. Functional synctiums can be found with the atrial walk and ventricular walls The hearts’ fibrous skeleton seperates masses of cardiac muscle fiber.