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Pearson's ComprehensiveMedical Assisting

Administrative and Clinical Competencies

CHAPTER

THIRD EDITION

Pearson's Comprehensive Medical Assisting:Administrative and Clinical Competencies, 3/eBeaman | Routh | Papazian-Boyce | Sesser | Mills | Maly

Copyright © 2015, 2011 by Pearson Education, Inc.All Rights Reserved

The Cardiovascular SystemLesson 1:Overview of the Cardiovascular System

27



Lesson Objectives

Upon completion of this lesson, students should be able to:

1. Define and spell the terms to learn for this chapter.

2. Identify the organs that make up the cardiovascular system.

3. Identify the structures that make up the heart and briefly explain the function of each.



Lesson Objectives

Upon completion of this lesson, students should be able to:

4. Explain the conduction system of the heart.

5. Explain the functions of the arteries, veins, and capillaries.



Overview of theCardiovascular System

• Cardiovascular system consists of:

Heart

• Responsible for movement of blood through cardiovascular system throughout entire body, providing oxygen and removing waste

Vessels

Blood



FIGURE 27-1 Location of the heart in the chest cavity.




• The Heart

Four-chambered muscular pump

About size of a fist

Weighs approximately 9 ounces

Cone shaped, with apex at most inferior point

Consists of three linings (layers)



Critical Thinking Question

1. What is meant by endocarditis, myocarditis, and pericarditis?




• The Heart

Pericardium

• Outer lining; covers heart and large blood vessels attached to it

Myocardium

• Middle layer, or heart muscle; thickest layer




• The Heart

Endocardium

• Innermost lining; thin and smooth; contains part of electrical conduction system of heart



FIGURE 27-2 Linings of the heart.




• The Heart

Septum

• Wall that separates left and right sides of heart

• Right side moves blood from body to lungs

• Left side pumps blood back to body




• The Heart

Two upper chambers (atria) receive blood coming into heart from body or lungs

Two lower chambers (ventricles) pump blood out of heart to lungs or body



FIGURE 27-3 The heart: interior view of the heart chambers.




• Blood Flow Through the Heart

Pumping action of heart occurs with contraction of cardiac muscle

Superior vena cava vein brings blood from head and upper chest

Inferior vena cava vein brings blood from below heart





Right atrium receives blood delivered to heart from body via superior and inferior vena cava

From right atrium, heart pumps blood through a valve into right ventricle





Tricuspid valve connects right atrium to right ventricle

Right ventricle pumps blood out through pulmonary valve into pulmonary artery, which carries blood to lungs





Blood that enters right atrium and then right ventricle is deoxygenated blood

When right ventricle pumps this blood to lungs, there is a gas exchange

Blood passes off its carbon dioxide into alveoli of lungs and then it is exhaled from the body





Blood takes on oxygen from air that has been breathed into the same air sacs of the lungs

Blood that returns to heart from lungs is now oxygenated blood





Pulmonary vein carries oxygenated blood from lungs; empties it into left atrium of heart

Blood leaves left atrium through bicuspid valve





Blood enters left ventricle, which pumps oxygenated blood out from heart to the body

Blood leaves left ventricle through aortic valve and enters aorta (largest artery in body)

Blood journeys through arteries that branch off from aorta to all regions of body



FIGURE 27-4 The flow of blood valves of the heart.





Heart valves function as gateways, never allowing blood to flow backward

Damaged or diseased valve can allow blood to escape and flow backward through valve (heart murmur)

Sound murmur makes is known as a bruit



FIGURE 27-5 The valves of the heart.




1. What happens when the coronary arteries get blocked?




• Vascular System of the Heart

Coronary arteries supply oxygenated blood to heart

After nourishing heart muscle, deoxygenated blood drained into coronary sinus by coronary veins and then back into right atrium for oxygenation

Occlusion deprives heart muscle of oxygen, causing chest pain



FIGURE 27-6 Coronary circulation: (A) coronary vessels portraying the complexity and extent of the coronary circulation; (B) coronary vessels that supply the anterior surfaces of the heart.





Permanent damage to heart tissue can occur if cardiac muscle deprived of oxygen for long period of time

• Ischemia

• Lack of blood flow to heart

• Myocardial infarction (MI)

• Death of heart muscle





Cardiac arrest

• Occlusion in heart causes heart to stop beating (pumping blood)

Hypoxia

• Lack of oxygen to tissues caused by ischemia and infarction




• Conduction System of the Heart

Heart's rate and rhythm controlled by autonomic nervous system

• Sinoatrial node

• Atrioventricular node

• Atrioventricular bundle (Bundle of His)



FIGURE 27-7 The conduction system of the heart.





Sinoatrial (SA) Node

• Pacemaker of heart

• Located in upper wall of right atrium

• Responsible for initiating heartbeat

• Initiate 60 to 80 beats (contractions) per minute





Atrioventricular (AV) Node

• Located under endocardium of right atrium and between atria and ventricles

• When electrical impulse from SA node reaches this point, AV node delays impulse for fraction of a second to ensure atrium has completely emptied





Atrioventricular (AV) Node

• Senses when ventricles have filled

• Sends an impulse that reaches Bundle of His





Bundle of His

• Also known as atrioventricular (AV) bundle

• Made up of muscle fibers

• Located in septum of heart

• Divides into right and left bundle branches

• Impulse travels from bundle branches into Purkinje fibers





Purkinje Fibers

• Specialized conductive fibers

• Located within walls of ventricles

• Responsible for relaying cardiac impulses to cells of the ventricles prompting ventricles to contract




• The Cardiac Cycle

All events that occur during one heartbeat

Heart beats about 70 times per minute; can vary from 60 to 110 beats per minute





Factors that cause heart rate to increase:

• Exercise

• Stress

• Excitement

• Smoking

• Rise in body temperature





Atrial diastole

Atrial systole

Ventricular diastole

Ventricular systole

• Systole: contraction phase of heart

• Diastole: relaxation phase of heart



FIGURE 27-8 The cardiac cycle showing systole and diastole.





Heartbeat produces sounds known as "lubdup" sounds as chambers contract and valves close

"Lub," heard when ventricles contract and AV valves close

"Dup," is sound of ventricles relaxing and semilunar valves closing

• Ausculation: listening for flow of blood with stethoscope



FIGURE 27-9 An overview of the arterial system.



Blood Vessels

• Arteries

Vessels that carry blood away from heart

High pressure by heartbeat propels blood forward through arteries

Elastic tubes that expand with pressure and relax between beats

Easy to palpate for pulse and purposes of recording heart rate



FIGURE 27-10 The primary pulse points of the body.



Blood Vessels

• Arteries

Radial

Brachial

Carotid

Temporal

Femoral

Popliteal

Dorsalis pedis

Anterior tibial



Critical Thinking Questions

1. Do all arteries take blood from or to the heart?

2. Do all veins take blood from or to the heart?



FIGURE 27-11 An overview of the veins in venous circulation.



Blood Vessels

• Veins

Thin-walled vessels that transport blood to the heart

Contain valves that prevent blood from flowing backward



Blood Vessels

• Veins

Low pressure is reason why veins need valves to prevent backflow

Have elastic walls

• Venipuncture (phlebotomy): process of removing blood from veins for examination




1. When do veins carry oxygenated blood?




1. How do arteries and veins get many of their names?



Blood Vessels

• Capillaries

Microscopic blood vessels

Blood offloads oxygen and nutrients to cells and picks up waste material from the cells

Blood then transports carbon dioxide and waste material from capillaries to venules

Facilitates exchange of gases and nutrients at level of the cells



Pulmonary and Systemic Circulation

• Pulmonary Circulation

Route blood takes from heart to lungs via pulmonary artery and back to heart via pulmonary vein

Carries deoxygenated blood from right side of heart to lungs and carries oxygenated blood back to left side of heart



FIGURE 27-12 Systemic and pulmonary circulation.



Pulmonary and Systemic Circulation

• Systemic Circulation

Delivers oxygenated blood and other nutrients to body cells

Carries carbon dioxide and waste products away from cells for elimination from body




1. What are some of the problems that might cause trouble in the cardiovascular system? Be specific.



Blood Pressure

• Force exerted by blood against inner walls of arteries



Blood Pressure

• Continually changes, depending on:

Activity

Temperature

Diet

Emotional state

Posture

Physical condition

Medication use




1. Where can you measure the pressure of the blood flow through the heart?



Blood Pressure

• Usually measured in brachial artery with a sphygmomanometer

Systolic blood pressure

• Pressure at highest in arteries during ventricular contraction

Diastolic blood pressure

• When ventricles relax and blood pressure at lowest



Blood Pressure

• Usually measured in brachial artery with a sphygmomanometer

Recorded as fraction

• Systolic blood pressure over diastolic blood pressure

Average resting blood pressure for young adult below 120/80



Blood Pressure

• Pulse Pressure

Difference between systolic and diastolic blood pressures

Normal is 30 to 50 points

Indication of tone of arterial walls




1. What kind of patient education or information might you give your patient?



Questions?

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