Transcript Cardiovascular System: The Heart Chapter 18 Part 1

Trace the pathway of blood (    )through the
body using the following terms:
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Aorta
Right atrium
Left atrium
Right ventricle
Left ventricle
Lungs
Vena Cava
Venules
Arterioles
Capillaries
Body tissues
Pulmonary artery
Pulmonary vein
The Heart
Functions of the Heart
• Generating blood pressure
• Routing blood
– Heart separates pulmonary and systemic
circulations
• Ensuring one-way blood flow
– Heart valves ensure one-way flow
• Regulating blood supply
– Changes in contraction rate and force
match blood delivery to changing
metabolic needs
Size, Shape, Location of Heart
• Size of a closed fist
• Shape
– Apex: Blunt rounded
point of cone
– Base: Flat part at
opposite of end of
cone
• Located in thoracic
cavity in
mediastinum
External Anatomy
• Four chambers
– 2 atria
– 2 ventricles
• Major veins
– Superior&
Inferior vena
cava
– Pulmonary veins
• Major arteries
– Aorta
– Pulmonary trunk
External Anatomy
External anatomy: anterior
External anatomy: posterior
Pericardium
Heart Wall
• Three layers of tissue
– Epicardium: (aka
visceral pericardium)
This serous membrane
of smooth outer surface
of heart
– Myocardium: Middle
layer composed of
cardiac muscle cell and
responsibility for heart
contracting
– Endocardium: Smooth
inner surface of heart
chambers
Myocardium
• Cardiac muscle
• Fibrous skeleton of the heart
– Consists of four dense connective
tissue rings
– Prevents overstretching of the valves
– Serves as a point of insertion for
cardiac muscle and as an electrical
insulator.
Cardiac Muscle
• Elongated, branching cells containing 1-2 centrally
located nuclei
• Contains actin and myosin myofilaments
• Intercalated disks: Specialized cell-cell contact
with Desmosomes and gap junctions
• Electrically, cardiac muscle behaves as single unit
Histology of cardiac muscle tissue
The chambers of the heart
Systemic & Pulmonary Circulation
Heart Valves
• Atrioventricular
(AV)
– Tricuspid
– Bicuspid or
mitral
• Semilunar
– Aortic
– Pulmonary
• Prevent blood
from flowing
back
The AV valves
The semilunar valves
Location of Heart Valves
Blood Flow Through Heart
Intrinsic Conduction System
• Sinoatrial node/pacemaker
– Crescent shaped node in right atrium
– Enforces a contraction rate of 75
beats/min
• Atrioventricular node
– Junction of atria and ventricles
• Atrioventricular bundle/bundle
of His
– In interventricular septum
• Purkinje fibers
– Spread within the muscle of the
ventricle walls
The conduction system
The excitation of the heart and ECG
Systole contraction
Diastole Relaxation
Events of the Cardiac Cycle
Normal Cardiac Cycle
Cardiac Cycle
20-25
Heart sounds
• Lup-dup, pause, lupdup, pause
• First heart sound or “lubb”
– Closing of AV valves at beginning of
ventricular systole
• Second heart sound or
“dupp”
– Closing of SL valves at beginning of
ventricular diastole, lasts longer
• Third heart sound (occasional)
– Caused by turbulent blood flow into
ventricles and detected near end of
first one-third of diastole
Heart Mnemonics
Valves
TRIPS BIAS
TRIcuspid
Pulmonary
Semilunar
BIcuspid
Aortic Semilunar
Valves
TRIPS, MI ASs
(uses MItral instead of
BIcuspid)
TRIcuspid
Pulmonary
Semilunar
MItral
Aortic Semilunar
Valves-Atriums
"LAB RATs"
Heart valves: closure
sequence
Many Things Are
Possible":
Electrical Signal
The patient's family are
all having Heart
attacks, you must
SAVe HIS KIN!"
SA node --->
AV node --->
HIS (bundle of) -->
PurKINje fibers
Aorta Branches
Know your ABC'S:
Aortic arch gives rise to:
Brachiocephalic trunk
left Common Carotid
left Subclavian
Left Atrium: Bicuspid
Right Atrium: Tricuspid
Mitral, Tricuspid,
Aortic, Pulmonary
Electrocardiogram
P wave
depolarization of
the atria
QRS complex
depolarization of
the ventricle
T wave
repolarization of
ventricles
The cardiac cycle:
Ventricular filling
The cardiac cycle:
Ventricular systole
The cardiac cycle:
Isovolumetric relaxation
Resources
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Heart Sounds & Cardiac Arrhythmias
Live Cardiac Exam Video
Anatomy Links
Cardiac Cycle
Cardiac Cycle Graphics
Interactive Physiology Review