A Complete Human Heart Presentation

1. 11/15/2008
Objectives
Cardiovascular System
Heart
William T. Budd
Virginia Commonwealth University
Center for the Study of Biological Complexity
Medical Careers College
Components of cardiovascular
system
Location of heart
Structure of the heart
Layers
Coverings
Chambers
Structure and function of myocardial
valves
Location of Heart
HeartHeart- circulates blood through vessels
Blood vessels
ArteriesArteries- away from heart
VeinsVeins- towards heart
CapillariesCapillaries- location of internal respiration
BloodBlood- transport medium
Coverings of the heart
• posterior to sternum
• medial to lungs
• anterior to vertebral column
• base lies beneath 2nd rib
• apex at 5th intercostal space
• lies upon diaphragm
Coverings of Heart
Pericardium-loose fitting, double layered sac
Visceral pericardium-serous membrane that is
on the surface of the heart muscle
Parietal pericardium- inner layer of sac; secretes
pericardial fluid
Pericardial fluid- (Serous fluid)-fluid that is
between the parietal and visceral pericardium
which prevents friction as the heart beats.
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Layers of heart tissue
Epicardium
Myocardium
Endocardium
Endocardium
Inner lining
Smooth surface that permits blood to
move easily through the heart without
agglutination.
Continuous with lining of blood vessels
Myocardium
Middle layer made of cardiac muscle
Forms the bulk of the heart wall
Contains the septum - a thick muscular
septumwall that completely separates the blood in
the right side of the heart from the blood in
the left side.
Epicardium
Protective, outer layer of the heart wall
same as the visceral pericardium
The coronary blood vessels that nourish
the heart wall are located here
Wall of the Heart
Endocardium – lines the heart chambers
Myocardium – Strong, muscular layer of heart
Epicardium – Outer, serous layer of heart
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Chambers
Right Atrium
Thinner wall than ventricles
Receives deoxygenated blood from vena cava
Passes blood through tricuspid valve into right
ventricle
Chambers
Left Atrium
Receives freshly oxygenated blood from
pulmonary vein
Passes blood to left ventricle through
mitral valve
Chambers
Right Ventricle
Thicker wall than atria
Comprises most of anterior surface of
heart
Circulates deoxygenated blood to lungs
through the pulmonic valve into pulmonary
trunk
Chambers
Left Ventricle
Receives blood from left atrium
Thickest myocardial wall
Forms apex of heart
Sends blood to systemic circulation via
aorta
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4. 11/15/2008
Septa
Interatrial septum
Muscular division b/w atria
Foramen ovale- opening in fetus
ovaleFossa ovalis- shallow depression; remnants of
ovalisforamen ovale
Interventricular septum
Thick muscular wall
Seperates ventricles
Heart Valves
FunctionFunction- prevent
blood from flowing
backwards
Responds to
changes in pressure
Two types of valves
in heart
Semilunar valves
Located at exit of ventricles, originiate
from endothelial lining of veins
Heart contains two semilunar valves
Pulmonic
Aortic (Frequently damaged by Htn)
Htn)
Atrioventricular
valves (AV)
SemiSemi-lunar valves
Atrioventricular Valves
Valve cusps are
connected to papillary
muscles
Chordae tendineaetendineaetiny collagen cords
that anchor cusps of
valve to papillary
muscles
Atrioventricular Valves
Left AV valve (Mitral, bicuspid)
Contains 2 cusps
Subject to abuse
Right AV valve (Tricuspid)
Contains 3 cusps
Not subjected to great abuses
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5. 11/15/2008
Vessels of Heart
Coronary
Arteries
Aorta
Vena Cava
Pulmonary Veins
Pulmonary Trunk and
pulmonary arteries
•2 Main Coronary
Arteries
•Right CA- branches
into some marginal
arteries; supplies RV
and posterior of heart
•Left CA- branches into
AIA (LAD) and
circumflex; supplies LV
Coronary Veins
Transport deoxygenated
blood to coronary sinus
Coronary Sinus drains
into RA
Contractile Cells of Heart
Remember myosin and actin
Presence of calcium in cytoplasm leads to
contraction
Action potential is 30X longer than skeletal
muscle
Cardiac Myocyte Physiology
Striated cells
Adhere to sliding
filament theory
Shorter cells,
branched, one nucleus
per cell
Connected tightly by
intercalated disks
Contain gap junctions
De Polarization
Re
Na+
Na+
Na+
Na+
Na+
K+
Na+
K+
K+
Na+
K+
- 70mV
Na+
K+
Na+
30 mV
130 mV
K+
Cardiac Cell
Ca++
Ca++
Ca++
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6. 11/15/2008
Conduction System
Cardiac cells are automaticitic
They can depolarize spontaneously
Autorhythmic cells
NonNon-contractile cells,
selfself-excitable,
generate spontaneous action potentials,
Trigger heart contractions
Conduction System
Located in
SA node
AV node
AV bundle
Bundle branches
Purkinkie system
Intrinsic Rates
Three potential areas capable of beginning
cardiac conduction
SA Node- Located in right atria; 60-100 bpm
Node60AV Node- Located at AV junction; 40-60 bpm
Node40Ventricular System- Ventricles; < 40
System• Rate depends upon where in ventricles conduction
originates
Atrial Depolarization
Visualized
as P wave
Normal
duration is
0.120.12-0.16
seconds
Atrial Delay
Visualized
as PR
interval
Normal
duration is
0.120.12- 0.20
seconds
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7. 11/15/2008
Ventricular Depolarization
Visualized
as QRS
complex
Normal
duration is
less than
0.12
seconds
Ventricular Repolarization
Visualized
as T wave
Normal
duration is
0.160.16- 0.20
seconds
Absolute
and relative
period of
refraction
Innervation of heart
Heart rate can be influenced by autonomic
nervous system
Sympathetic
Speeds up heart rate and increases force of
contraction
Parasympathetic
Slows down heart rate
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