Medical assisting Administrative and clinical procedures (5e) Chapter 26 The cardiovascular system

After studying this chapter you will be able to: Describe the structure of the heart and the function of each; explain the cardiac cycle, including the cardiac conduction system; compare pulmonary and systemic circulation; differentiate among the different types of blood vessels and their functions;...

The Cardiovascular

System

Learning Outcomes (cont.)

26.1 Describe the structures of the heart

26.2 Explain the cardiac cycle, including the

cardiac conduction system.

26.3 Compare pulmonary and systemic

circulation.

Learning Outcomes (cont.)

26.4 Differentiate among the different types

of blood vessels and their functions

26.5 Explain blood pressure and tell how it

is controlled

26.6 Describe the causes, signs and

symptoms, and treatments of various

diseases and disorders of the

cardiovascular system.

• Lungs for oxygen

• Digestive system for nutrients

– Also circulates waste products for removal

The Heart

• Cone-shaped organ

• Size of a loose fist

• Slightly left of the midline

Cardiac Membranes

• Pericardium

– Covers the heart and large blood vessels

– Fibrous outer layer

– Visceral pericardium ~ epicardium

– Parietal pericardium

• Pericardial sac

• Pericardial cavity – pericardial fluid Membranes Cardiac

The Heart Wall

• Epicardium

• Myocardium

• Endocardium

– Thin, smooth layer

– Contains part of electrical conduction system

Heart Wall

Heart Chambers and Valves

– Two atria

• Upper chambers

• Interatrial septum

– Atrioventricular septum separates the atria

from the ventricles

– Two ventricles

• Lower chambers

• Interventricular septum

Click for View of Heart

Heart Chambers and Valves (cont.)

• Valves between atria and ventricles

– Tricuspid ~ three cusps

– Bicuspid ~ two cusps

• Valves between ventricles and arteries

– Pulmonary semilunar

– Aortic semilunar Click for

View of Heart

Apply Your Knowledge

Match the following:

Cardiac Cycle

One heart beat = one cardiac cycle

1.Right atrium contracts  tricuspid valve opens

 blood flows into right ventricle

2.Left atrium contracts  bicuspid valve closes

 blood flows into left ventricle

Cardiac Cycle (cont.)

3 Right ventricle contracts  tricuspid valve

closes  pulmonary semilunar valve opens 

blood is pushed into pulmonary artery

4 Left ventricle contacts  bicuspid valve closes

 aortic semilunar valve opens  blood is

pushed into aorta

Cardiac Cycle (cont.)

Heart Sounds

• Lubb

– First sound

– Occurs when ventricles contract and the tricuspid and

bicuspid valves snap shut

• Dubb

– Second sound

– Occurs when atria contract and the pulmonary and

aortic valves snap shut

• Murmur – abnormal heart sound

Click for Heart Sounds

Cardiac Conduction System

– Between atria and just above ventricles

– Sends impulse to the bundle of His

Click for Conduction System

Cardiac Conduction System (cont.)

• Bundle of His

– Between ventricles

– Right and left bundle branches

– Sends impulse to Purkinje fibers

• Purkinje fibers

– Lateral walls of ventricles

– Ventricles contract

Click for Conduction System

Apply Your Knowledge

Match the following:

fibers

center

– Delivers oxygen and nutrients

– Removes carbon dioxide and waste products

Circulation (cont.)

Right Atrium

Right Ventricle

Left Atrium

Bicuspid Valve

Left Ventricle

Pulmonary Semilunar Valve

Tricuspid Valve

Body

Aortic Semilunar Valve

Pulmonary Circulation

Systemic Circulation

Apply Your Knowledge

What are the functions of the pulmonary and

systemic circulations?

ANSWER: The pulmonary circulation functions to

oxygenate the blood and remove carbon dioxide The

systemic circulation delivers oxygen and nutrients to

and removes carbon dioxide and waste products

from the body’s cells.

Blood Vessels

• Form a closed

pathway that carries

blood from the heart

to cells and back to

the heart

Arteries and Arterioles

• Thick muscular wall

• Carry blood under

• Aorta

Veins and Venules

Veins and Venules

• Venules

• Pulmonary veins – oxygenated blood

• Superior and inferior vena cava

• Hepatic portal

system

• Branches of arterioles

• Connect arterioles to venules

• Exchange vessels

– Oxygen and nutrients

– Carbon dioxide and waste

products – Water

Apply Your Knowledge

ARTERIES:

Match the following:

coronary arteries A exchange vessels

arterioles B supply blood to the heart tissues

veins C largest veins in the body

arteries D supplies the forearm and hand

capillaries E carry blood toward heart

vena cavae F drain the knees

radial artery G strongest blood vessels

popliteal veins H small branches of arteries

– Blood pressure in arteries lowest

• Pulse

Blood Pressure (cont.)

• Factors affecting blood pressure

– Cardiac output

– Blood volume

– Vasoconstriction and vasodilation

– Blood viscosity

Blood Pressure (cont.)

• Controlled by the amount of blood pumped out of the heart

• Starling's law of the heart

– Blood entering the left ventricle stretches its

wall– The more the wall is stretched the harder it

will contract

Blood Pressure (cont.)

• Baroreceptors

– Help regulate blood pressure

– Located in the aorta and carotid arteries

– Send information to cardiac center in the

medulla oblongata

Apply Your Knowledge

What is the difference between the systolic

pressure and diastolic pressure?

ANSWER: Systolic pressure is the result of the

contraction of the ventricles increasing the pressure in

the arteries Diastolic pressure is the result of the

relaxation of the ventricles lowering the pressure in the

arteries.

Cardiovascular System (cont.)

Disease Description

Aneurysm A ballooned, weakened arterial wall

Arrhythmias Abnormal heart rhythms

Endocarditis Inflammation of the innermost lining of the heart, including valves

Myocarditis Inflammation of the muscular layer of the heart

System (cont.)

Disease Description

Pericarditis Inflammation of the membranes that

surround the heart (pericardium)

Congestive

heart failure Weakening of the heart over time; heart is unable to pump enough blood

to meet body’s needs

System (cont.)

Disease Description

Hypertension High blood pressure; consistent

resting blood pressure equal to or greater than 140/90 mm Hg

Mitral valve

prolapse Valve falls into the left atrium during systole; prevents proper

closingMurmurs Abnormal heart sounds

heart valves The valve does not fully open; aortic stenosis, mitral stenosis

Thrombophlebitis Blood clots and inflammation

develop in a veinVaricose veins Twisted, dilated veins

Apply Your Knowledge

ANSWER:

True or false:

A myocardial infarction results from a lack of

oxygen to the cardiac muscle

Myocarditis is inflammation of the innermost

lining of the heart

A potentially fatal arrhythmia is ventricular

In Summary

26.1 The structures of the heart include the

pericardium, epicardium, myocardium, and

Contractions are initiated by the cardiac conduction system.

In Summary (cont.)

26.3 Pulmonary circulation: Right atrium 

tricuspid valve  right ventricle  pulmonary

semilunar valve pulmonary trunk 

pulmonary arteries  lungs pulmonary

veins  left atrium

Systemic circulation: Left atrium  bicuspid valve left ventricle  aortic semilunar

valve  aorta  arteries  arterioles 

capillaries  venules  veins  venae cavae 

right atrium

In Summary (cont.)

26.4 Types of blood vessels include arteries and

arterioles, which bring blood from the heart to the body; capillaries, which act as the

connectors between the arterioles and venules

The largest artery in the body is the aorta

Others arteries are listed in the chapter

The largest veins in the body are the superior and inferior venae cavae Others veins are

listed in the chapter

In Summary (cont.)

26.5 Blood pressure is the force exerted on the

inner wall of blood vessels by blood as it flows through vessels

It is highest in arteries and lowest in veins

Clinically, blood pressure refers to the force

of blood within the arteries

Blood pressure is largely controlled by the amount of blood pumped out of the heart, but various other events also may raise and

lower blood pressure

In Summary (cont.)

26.6 Many different types of cardiac and blood

diseases are described within this chapter

The signs, symptoms, and treatments are as varied as the diseases themselves

The last section of this chapter outlines the most common of these diseases, their signs and symptoms, as well as their treatments

Your work is to discover your world and then with all your heart give yourself to it

~ Buddha

End of Chapter 26