Memmler’s
The Human Body in Health and Disease
11th edition
Chapter 14
The Heart and Heart Disease
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Circulation and the Heart
Circulation
•Continuous one-way circuit of the blood vessels
•Propelled by heart
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Location of the Heart
•Between the lungs
•Left of the midline of the body
•In mediastinum
•Apex pointed toward left
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Structure of the Heart
Three tissue layers
•Endocardium lines heart’s interior
•Myocardium is thickest layer; the heart muscle
•Epicardium is thin outermost layer
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The Pericardium
The sac that encloses the heart
•Fibrous pericardium holds heart in place
•Serous membrane
– Parietal layer
– Pericardial cavity
– Visceral layer (epicardium)
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Layers of the
heart wall and
pericardium. The
serous
pericardium
covers the heart
and lines the
fibrous
pericardium.
ZOOMING IN
• Which layer of
the heart wall is
the thickest?
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Question:
Which layer of the heart is the heart
muscle?
a. epicardium
b. myocardium
c. pericardium
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Answer:
b. myocardium
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Checkpoint 14-1: What are the names of the innermost,
middle, and outermost layers of the heart?
Checkpoint 14-2: What is the name of the sac that
encloses the heart?
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Special Features of the Myocardium
Cardiac muscles
•Are lightly striated (striped)
•Have single nucleus cells
•Are controlled involuntarily
•Have intercalated disks
•Have branching muscle fibers
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Divisions of the Heart
Double pump
•Right side pumps blood low in oxygen to the lungs
– Pulmonary circuit
•Left side pumps oxygenated blood to remainder of body
– Systemic circuit
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Four Chambers
•Right atrium
– Receives low-oxygen blood returning from body tissue
through superior vena cava and inferior vena cava
•Left atrium
– Receives high-oxygen blood from lungs
•Right ventricle
– Pumps blood from right atrium to lungs
•Left ventricle
– Pumps oxygenated blood to body
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The heart as a double
pump. The right side of
the heart pumps blood
through the pulmonary
circuit to the lungs to
be oxygenated; the left
side of the heart
pumps blood through
the systemic circuit to
all other parts of the
body.
ZOOMING IN
• What vessel carries
blood into the systemic
circuit?
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The heart and
great vessels.
ZOOMING IN
• Which heart
chamber has the
thickest wall?
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Checkpoint 14-3: The heart is divided into four chambers.
What is the upper receiving chamber on each side called?
What is the lower pumping chamber called?
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Question:
Which chamber of the heart receives
oxygenated blood coming in from the
lungs in the pulmonary veins?
a. right atrium
b. left ventricle
c. left atrium
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Answer:
c. left atrium (upper left chamber)
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Four Valves
•Atrioventricular valves
– Entrance valves
– Right atrioventricular (AV) valve (tricuspid valve)
– Left atrioventricular (AV) valve (bicuspid valve)
•Semilunar valves
– Exit valves
– Pulmonary valve
– Aortic valve
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Valves of the heart (superior view from anterior, atria removed). (A) When the heart is
relaxed (diastole), the AV valves are open and blood flows freely from the atria to the
ventricles. The pulmonary and aortic valves are closed. (B) When the ventricles contract,
the AV valves close and blood pumped out of the ventricles opens the pulmonary and
aortic valves. ZOOMING IN • How many cusps does the right AV valve have? The left?
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Pathway of blood through the
heart.
Blood from the systemic circuit
enters the right atrium (1)
through the superior and inferior
venae cavae, flows through the
right AV (tricuspid) valve (2),
and enters the right ventricle
(3). The right ventricle pumps
the blood through the pulmonary
(semilunar) valve (4) into the
pulmonary trunk, which divides
to carry blood to the lungs in the
pulmonary circuit.
Blood returns from the lungs in
the pulmonary veins, enters the
left atrium (5), and flows
through the left AV (mitral)
valve (6) into the left ventricle
(7). The left ventricle pumps the
blood through the aortic
(semilunar) valve (8) into the
aorta, which carries blood into
the systemic circuit.
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Checkpoint 14-4: What is the purpose of valves in the
heart?
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Blood Supply to the Myocardium
Coronary circulation
•Right coronary artery
•Left coronary artery
•Coronary sinus
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Blood vessels that supply the myocardium. Coronary
arteries and cardiac veins are shown. (A) Anterior
view. (B) Posterior view.
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Opening of coronary arteries in the aortic valve (anterior view).
(A) When the left ventricle contracts, the aortic valve opens. The
valve cusps prevent filling of the coronary arteries. (B) When the
left ventricle relaxes, backflow of blood closes the aortic valve
and the coronary arteries fill.
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Checkpoint 14-5: The myocardium must have its own
vascular system to supply it with blood. What name is
given to this blood supply to the myocardium?
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Function of the Heart
Left and right sides of heart work together in cardiac cycle
(heartbeat)
•Systole (active phase, contraction)
•Diastole (resting phase)
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The cardiac cycle.
ZOOMING IN • When the ventricles contract, what valves close? What valves
open?
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Cardiac Output
Calculating cardiac output
•Cardiac output (CO)
•Stroke volume (SV)
•Heart rate (HR)
•CO = HR 3 SV
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Checkpoint 14-6: The cardiac cycle consists of an
alternating pattern of contraction and relaxation. What
name is given to the contraction phase?
Checkpoint 14-7: Cardiac output is the amount of blood
pumped by each ventricle in 1 minute. What two factors
determine cardiac output?
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The Heart’s Conduction System
Electrical energy stimulates heart muscle
•Nodes
– Sinoatrial (SA) node (pacemaker)
– Atrioventricular (AV) node
•Specialized fibers
– Atrioventricular bundle (bundle of His)
– Purkinje fibers (conduction myofibers)
•Intercalated disks
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Conduction
system of the
heart. The
sinoatrial (SA)
node, the
atrioventricular
(AV) node, and
specialized fibers
conduct the
electrical energy
that stimulates
the heart muscle
to contract.
ZOOMING IN
• What parts of
the conduction
system do the
internodal
pathways connect?
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The Conduction Pathway
Sinus rhythm
•Sinoatrial (SA) node
•Atria
•Atrioventricular (AV) node
•Internodal pathways
•Bundle of His
•Bundle branches and Purkinje fibers
•Ventricles
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Checkpoint 14-8: The heartbeat is started by a small
mass of tissue in the upper right atrium. This structure is
commonly called the pacemaker, but what is its scientific
name?
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Control of the Heart Rate
Influences that allow heart to meet changing needs rapidly
•Autonomic nervous system (ANS)
•Sympathetic nervous system
•Parasympathetic system
– Cranial nerve X
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Variations in Heart Rates
•Bradycardia
•Tachycardia
•Sinus arrhythmia
•Premature beat (extrasystole)
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Heart Sounds
•Lub
•Dup
•Murmurs
– Organic
– Functional
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Checkpoint 14-9: What system exerts the main influence
on the rate and strength of heart circulation?
Checkpoint 14-10: What is a heart murmur?
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Question:
What is the medical term for a heart
rate of more than 100 beats/min?
a. bradycardia
b. hypercardia
c. tachycardia
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Answer:
c. tachycardia
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Heart Disease
Most common cause of death in industrialized countries is
heart and circulatory system disease
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Classifications of Heart Disease
•Anatomical classification
–
Endocarditis
–
Myocarditis
–
Pericarditis
•Causative factors classification
–
Congenital heart disease
–
Rheumatic heart disease
–
Coronary artery disease
–
Heart failure
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Congenital Heart Disease
Congenital heart disease often results from fetal
development defects
•Atrial septal defect
•Patent (open) ductus arteriosus
•Ventricular septal defect
•Coarctation of the aorta
•Tetralogy of Fallot
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Checkpoint 14-11: What is congenital heart disease?
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Rheumatic Heart Disease
•Streptococci release toxins during infection
•Antibodies that combat toxin also attack heart valves
•Heart valves become inflamed
•Valve cusps thicken and harden
•Pulmonary congestion occurs
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Checkpoint 14-12: What types of organisms cause
rheumatic fever?
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Coronary Artery Disease
Coronary arteries can degenerate
•Myocardial infarction
– Creatine kinase released upon any muscle damage.
Tests for certain forms of CK indicate whether an MI
occurred.
•Angina pectoris
•Abnormalities of heart rhythm
•Treatment of heart attacks
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Checkpoint 14-13: Narrowing or blockage of the vessels
that supply the heart muscle causes coronary artery
disease. What degenerative process commonly causes
narrowing of these vessels?
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Question:
What is the name of the fatty substance
that builds up inside the vessel walls in
atherosclerosis?
a. plaque
b. lumen
c. thrombus
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Answer:
a. plaque
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Heart Failure
Heart is unable to pump sufficient blood
•Heart chambers enlarge
•Blood backs up into lungs
•Ventricular muscles have decreased ability
•Fluid accumulates in lungs, liver, abdomen, legs
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The Heart in the Elderly
How the heart can age
•Heart shrinks
•Decreased contraction strength
•Valves become less flexible
•Murmur develops
•Cardiac output decreases
•Abnormal rhythms
•Heart block
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Prevention of Heart Disease
•Risk factors that cannot be
modified
•Risk factors that can be
modified
– Age
– Smoking
– Gender
– Physical inactivity
– Heredity
– Weight
– Body type
– Diet
– Blood pressure
– Diabetes, gout
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Heart Studies
•Stethoscope
•Electrocardiograph (ECG or EKG)
– Electrodes
•Catheterization
– Fluoroscope
•Echocardiography (ultrasound cardiography)
– Oscilloscope
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Checkpoint 14-14: What do ECG and EKG stand for?
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Treatment of Heart Disease
•Medical approaches
•Surgical approaches
•Combined approaches
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Medications
•Digitalis
•Nitroglycerin
•Beta-adrenergic blocking agents (beta-blockers)
•Antiarrhythmic agents
•Slow calcium-channel blockers
•Anticoagulants
– Aspirin
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Correction of Arrhythmias
•Artificial pacemaker
– Set rate
– Only when heart skips beat
– Adjustable pacing rate
•Implantable cardioverter-defibrillator (ICD)
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Heart Surgery
•Coronary artery bypass graft (CSBG)
•Angioplasty
•Valve replacement
•Surgical transplantation of heart or heart and lungs
•Artificial heart
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Checkpoint 14-15: What technique is used to open a
restricted coronary artery with a balloon catheter?
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Question:
The technique to restore normal
heartbeat by either electric shock or
drugs is known as:
a. defibrillation
b. cardioversion
c. ablation
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Answer:
b. cardioversion
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End of Presentation
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