Replacing
hearts - nova
CARDIOVASCULAR SYSTEM
Cardiovascular System Functions
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The cardiovascular system allows exchange of oxygen
and carbon dioxide between blood and tissues
Accomplished by three components:
1.
2.
3.
Heart – pump blood
Vessels – transport network; arteries, veins and capillaries
Blood – transports dissolved gases, nutrients, hormones and
metabolic wastes
Organization of Cardiovascular System
A closed system with two circuits
1.
2.
Systemic Circuit – oxygenated
blood leaves the heart through the
aorta and returns to the heart
through systemic veins
Pulmonary Circuit– deoxygenated
blood leaves the heart through
pulmonary arteries and returns to
the heart through pulmonary veins
The Heart…size, shape and location
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Muscular organ composed of cardiac muscle
About the size of a closed fist
Weighs less than a pound
Located within the thoracic cavity
Flanked on either side by the lungs
The heart…coverings and wall
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Pericardium = double walled sac around the heart
 Protects
the heart and anchors it to surrounding structures
 Produces a lubricating fluid to create a frictionless
environment
 Pericarditis = inflammation of the
pericardium
The heart…coverings and wall
The wall of the heart is composed of three layers:
1.
Epicardium = continuous with the pericardium
2.
Myocardium = thick bundles of cardiac muscle; the
contractile part of the heart
3.
Endocardium = think sheet of endothelium that lines
the heart chambers
The heart…coverings and wall
Anatomy of the heart
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4 chambers
 Upper
chambers = atria = receiving chambers
 Lower chambers = ventricles = pumping chambers
 Left
ventricle forms the apex or point of the heart
 Interventricular septum divides ventricles
Chambers – Anterior View
Right atrium
Right Ventricle
Left atrium
Left Ventricle
Chambers – Posterior View
Left atrium
Left Ventricle
Right atrium
Right Ventricle
Chambers – Internal View
Right atrium
Right Ventricle
Left atrium
Left Ventricle
Anatomy of the heart
Heart Valves permit flow of blood in one direction
1. AV valves divide atria and ventricles; prevent backflow of
blood into atria when ventricles contract
 Bicuspid
valve (mitral valve) – between left atria and left ventricle
 Tricupsid valve between right atria and right ventricle
 Chordae Tendinae = tiny white cords that anchor the valves to the
walls of the ventricle
LAB RAT…
Left Atrium Bicuspid
Right Atrium Tricuspid
AV Valves
Anatomy of the heart
Heart Valves permit flow of blood in one direction
2. Semilunar valves guard the large vessels leaving the
ventricles; prevents arterial blood from falling back into the
ventricles
 Pulmonary
semilunar valve
 Aortic semilunar valve
Semilunar Valves
Anatomy of the heart
Great Vessels of the Heart
 Superior
and inferior vena cava – take deoxygenated blood
from the body to the right atrium
 Pulmonary trunk gives rise to Pulmonary arteries (left and right)
– take deoxygenated blood from right ventricle to lungs for
oxygen
 Pulmonary veins (left and right) – takes oxygenated blood from
lungs to left atrium
 Aorta – takes blood away from left ventricle to rest of body
Anatomy of the heart
Cardiac Circulation
 Coronary
arteries branch from the base of the aorta and
encircle the heart at the junction between the atria and
ventricles
 Compressed
when ventricles are contracting and fill when the
ventricles are relaxed
 Cardiac
veins drain the myocardium into the right atrium
Vessels – Anterior View
Superior vena cava
R. Pulmonary artery
R. Pulmonary
veins
Coronary vessels
Inferior vena cava
aorta
L. Pulmonary artery
Pulmonary trunk
L. Pulmonary
veins
Vessels – posterior view
aorta
L. Pulmonary artery
L. Pulmonary
veins
Superior vena cava
R. Pulmonary artery
R. Pulmonary veins
Inferior vena cava
Coronary vessels
When the heart beats
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The Right side of the heart
 Deoxygenated
 Right
blood flows into heart from vena cava
atrium
 Tricuspid valve
 Right ventricle
 Pulmonary semilunar valve
 Pulmonary artery
 Lungs (to pick up oxygen)
What’s behind a heartbeat
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The Left side of the heart
 Oxygenated
blood flows into heart from lungs via pulmonary
veins
 Left atrium
 Bicuspid valve (aka mitral valve)
 Left ventricle
 Aortic semilunar valve
 Aorta
 Body (to deliver oxygen)
Control of Heart Contraction
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READ
ONLY!!!
General info about cardiac muscle
 Cardiac
muscle cells contract spontaneously and
independently, even if all nervous connections are cut
 Muscle cells in different areas of the heart have different
rythms
 Atria
cells contract at a faster rate than ventricular cells
 An intrinsic control system regulates activity
Intrinsic Control System
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Intrinsic conduction system
 Sinoatrial
node (SA node)
 Atrioventricular node (AV node)
 Bundle of His
 Purkinje Fibers
Sinoatrial Node (SA node)
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The pacemaker of the heart
Located in right atrium
SA node sends out electrical impulse
Impulse spreads over atria, making them contract
Impulse travels to AV node
Atrioventricular node (AV node)
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Conducting cell group between atria and ventricle
Carries impulse to bundle of His
Bundle of His
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Conducting fibers in septum (divider between left
and right sides of the heart
Divides into right and left branches to a network of
branches in ventricles (Purkinje Fibers)
Purkinje Fibers
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Impulse shoots along Purkinje fibers causing
ventricles to contract
Deficiencies in normal pacemaker
function
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Bradycardia = SLOW heart rate
Tachycardia = FAST heart rate
List the parts of the intrinsic control
system of the heart in order…
Electrocardiogram (EKG or ECG)
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Recording of the electrical activity of the heart
Useful in detecting heart arrhythmias (irregularities)
Baseline of EKG is flatline
P
= atrial contraction
 QRS = ventricular contraction
 T = ventricular relaxation
Electrocardiogram
Cardiac Cycle
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Includes events of one heartbeat
 Systole
= contraction
 Diastole = relaxtion
 Normal Blood pressure = 120/80 where the 120 refers to
systolic pressure and 80 refers to diastolic pressure
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Predictable sequence of changes in blood volume and
pressure
1. mid-to-late diastole
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Complete relaxation
Pressure in heart is low
Blood flows passively into ventricle
Semilunar valves closed
Av valves open
Atria contract forcing blood into ventricle
2. Ventricular Systole
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Pressure in ventricles increases
AV valves close
Semilunar valves are forced open
Blood rushes out of ventricle
Atria are relaxed and filling
3. Early diastole
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Ventricles relax
Semilunar valves snap shut
Pressure drops in ventricles
AV valves open
Heart sounds
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Two distinct sounds can be heard with a stethoscope
“lub” “dup”
First heart sound (“lub”) is caused by the closing of the AV
valves
Second sound (“dup”) caused by closing of semilunar valves
Heart sounds
Clinical side of things
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Heart murmur = abnormal heart sounds
Ischemia = lack of adequate blood supply
Myocardial infarction = heart attack
Angina pectoris = crushing chest pain
Congestive heart failure = weakening of the heart
 Pulmonary
edema if left heart fails
 Systemic edema (swelling) if right heart affected
Congestive Heart Failure
Myocardial Infarction