Download The Heart

Heart
Chapter 13
Pages 252 – 273
Page 253
Functions of the Circulatory System

The heart is the pump that circulates blood to all
parts of the body

Arteries, veins, & capillaries transport the blood

Blood carries oxygen & nutrients to the cells &
carries waste products away

Lymph system returns excess fluid from the
tissues the circulation
Page ?
Major Blood Circuits

Blood leaves the heart through arteries & returns
by veins

Blood circulation routes
•
General or systemic circulation
•
Pulmonary circulation
Pages 253 – 254
 The
The Heart
circulatory system is efficient because of the
heart – a tough, simply constructed muscle about
the size of a closed fist; weighs about a pound
 Location: thoracic cavity (between the lungs);
apex of the heart points to the left
 Stethoscope allows you to hear the heartbeat
 If blood flow stops:
• 5 seconds or more = loss of consciousness
• 15 to 20 seconds = muscles twitch convulsively
• 4 to 5 minutes = brain cells are damaged
Page 253
Figure 13-1
Page 254
Structure of the Heart
Heart = Hollow, muscular, double pump
 Surrounding the heart is the Pericardium (a double
layer of fibrous tissue which is filled with pericardial
fluid)
 Epicardium (visceral or serous pericardium)= the
thin inner covering of the heart. [the outer layer of the
pericardium is the parietal or fibrous pericardium]
 Myocardium = Cardiac muscle tissue
 Endocardium = inner lining of the heart; covers the
heart valves & lines the blood vessels, providing a
smooth transit for the flowing blood.

Page 256
Structure of the Heart
 Interventricular
septum = completely separates
the blood in the right half & left half of the heart.
 Leading to the heart
• Superior & inferior vena cava
• Coronary sinus
• Pulmonary veins
 Leading away from the heart
• Pulmonary artery
• Aorta
Page 254
Figure 13-2
Page 255
Figure 13-3
Page 256
Chambers & Valves
 Septum
separates the heart into right and left
halves; then each of these halves are separated
into an upper & lower chambers
•
•
Upper chambers – Left & right atria (singular
atrium)
Lower chambers – Left & right ventricles
 Heart
has four valves which keeps blood flowing
in one direction
Page 256


Valves
Atrioventricular valves
• Tricuspid valve (separates the right atria and
right ventricle)
• Bicuspid or mitral valve (separates the left
atria and left ventricle)
Semilunar valves
• Pulmonary semilunar valve (opening of the
pulmonary arteries)
• Aortic semilunar valve (opening of the aorta)
Page 257
Physiology of the Heart
 Double
pump
•
Right side of the heart – Deoxygenated blood
•
Left side of the heart – Oxygenated blood
Page 257
Heart Rate & Cardiac Output
 Normal
adult rate is between 72-80 beats per
minute
 With each beat 60-80 mL of blood are ejected
from the ventricles = Stroke volume
 Cardiac output = stroke volume x heart rate
 Exercise increases cardiac output
Page 258
Heart Sounds
 lubb
dupp sounds = sounds the valves make
when they close
•
Lubb

•
Tricuspid and bicuspid valves (S1)
Dupp

Aortic and pulmonary valves (S2)
Pages 258 – 259
Conduction System

Electrical impulses cause rhythmic beating of the
heart
• Sinoatrial (SA) node [pacemaker] – sends out an
electrical impulse that begins/regulates the
heartbeat. This impulse causes the atria to contract.
It then sends its impulse to the AV node.
• Atrioventricular (AV) node – catches the impulse
& sends it on to the atrioventricular bundle (bundle
of His)
• Bundle of His – passes the impulse on to the
Purkinje fibers
• Purkinje fibers –causes the ventricles to contract
Page 258
Figure 13-7
Page 259
ECG or EKG
 The
electrocardiogram is a device to record the
electrical activity of the heart
• Systole – Contraction
• Diastole – Relaxation
 Positive & negative deflection
 P wave – atrial depolarization
 QRS – ventricular depolarization
 T waves – ventricular repolarization
Page 259
Page 259 SB
Effects of Aging
 Heart
muscle fibers replaced by fibrous tissue
 Heart valves increase in thickness
 Cardiac output decreases
 Changes become more significant when elderly
person becomes physically or mentally stressed
Pages 259 – 260
Prevention of Heart Disease
Heart disease is the leading cause of death for both
men & women in the US (Coronary heart disease)
• Risk factors – family history, high blood pressure,
high cholesterol, diabetes, current smoking,
physical inactivity, & obesity.
 Steps to lower risk or prevent heart disease
• Lower blood cholesterol levels & triglycerides
• Control & prevent high blood pressure
• Lose weight & have regular exercise & a healthy
diet
• No tobacco use
• Alcohol – Men: 2 drinks & Women: 1 drink

Pages 260 – 261
Diagnostic Tests – Noninvasive
 Angiography
 Cardiac
MRI
 Coronary calcium scoring/heart scan
 Echocardiography
 Electrocardiogram
 Exercise stress tests
 Holter monitor
 MUGA (multiple gated acquisition scan)
 Nuclear perfusion
Page 261
Diagnostic Tests – Invasive
 Cardiac
catheterization
 IVUS (intravascular coronary ultrasound)
 TEE
Page 261
Diagnostic Tests – Blood Tests
 Arterial
blood gases
 BNP
 Lipid
panel
 C-reactive protein
 Cardiac Troponin T
Page 262
Diseases of the Heart –
Common Symptoms
Arrhythmia – any change or deviation from the
normal rate or rhythm of the heart
 Bradycardia – slow heart rate (fewer than 60 beats
per minute)
 Tachycardia – rapid heart rate (more than 100 beats
pre minute
 Murmurs – indicate defects in the valves of the
heart.
 Mitral valve prolapse – the valve between the left
atrium & left ventricle closes imperfectly.

Page 262
Diseases of the Coronary Artery
 Coronary
artery disease (CAD) = a narrowing
of the coronary arteries that supply blood to the
heart muscle. If these arteries get blocked
completely a myocardial infarction may occur.
 Angina pectoris (angina) = severe chest pain that
arises when the heart does not receive enough
oxygen.
 Myocardial infarction (MI or heart attack) =
death of heart muscle caused by a lack of blood
supply to the myocardium.
Pages 262 – 264
Infectious Diseases of the Heart
 Pericarditis
= inflammation of the outer
membrane covering the heart.
 Myocarditis
= inflammation of the heart muscle
 Endocarditis
= inflammation of the membrane
that lines the heart & covers the valves. May lead
to a blood clot.
 Rheumatic
heart disease = results from frequent
strep throat infections that then travel to the heart.
May lead to the mitral valve leaking.
Page 264
Heart Failure
 When
the ventricles of the heart are unable to
contract effectively & blood pools in the heart
 Symptoms depend on which ventricle fails
• Left ventricle failure
 Dyspnea (shortness of breath)
• Right ventricle failure
 Engorgement of organs, edema (excessive
fluid in tissues) of the legs & feet, & ascites
(abnormal accumulation of serous fluid in
the abdominal cavity)
Page 264
Congestive Heart Failure
 Similar
to heart failure
 Left-sided
failure – pulmonary edema
 Right-sided
failure – fluid buildup throughout
body
 Treatment
•
Cardiotonics, diuretics, vasodilators, & betablockers
Pages 264 – 265
Rhythm/Conduction Defects

Heart block – interruption of the AV node message from
the SA node
• First-degree block – momentary delay at the AV node
before the impulse is transmitted to the ventricles.
• Second-degree block – 2 forms
 (1) cycles of delayed impulses until the SA nodes
fails to conduct to the AV node, & then returns to
near normal
 (2) characterized by a pattern of only every second,
third, or fourth impulse being conducted to the
ventricles.
• Third-degree block or complete heart block – no
impulse is carried over from the pacemaker.
Page 265
Rhythm/Conduction Defects

Premature contractions – arrhythmia disorder
that occurs when an area of the heart known as an
ectopic pacemaker (not the SA node) sparks &
stimulates a contraction of the myocardium
• Atrial fibrillation – when abnormal impulses
from the atria bombard the AV node.
• PVCs – originate in the ventricles & cause
contractions ahead of the anticipated beat.
• Ventricular fibrillation – rhythm breaks down
& muscle fibers contract at random, without
coordination.
Page 265
Types of Heart Surgery

Angioplasty (balloon surgery) = procedure to help
open clogged vessels
 Cardiac stents = tiny, webbed, stainless steel
devices that hold arteries open after an angioplasty.
 Coronary bypass = surgically providing a detour
or bypass to allow the blood supply to go around
the blocked area of a coronary artery.
 Transmyocardial laser revascularization (TMR)
= the use of lasers to puncture holes in the heart
muscle to improve blood flow.
Page 266 – 267
Heart Transplants
 Used
as a last resort
 Problems
include:
•
Histocompatibility = matching of tissue type
•
Organ rejection
Page 268 SB
Medical Highlights
Pacemaker = surgical implanted, battery-operated
electronic device that sends electrical impulses to
regulate the rhythm of the heart
 Cardiac resynchronization therapy = uses a special
type of pacemaker to recoordinate the action of both
the right & left ventricles of the heart, pacing both
ventricles simultaneously.
 Defibrillator = used to discharge a strong electrical
current through the patient’s heart (internal or
external)
 Heart pumps = implanted in the abdomen &
attached to a weakened heart to help it pump
