Transcript Comparative Vertebrate Physiology

Human Anatomy and
Physiology
Cardiovascular physiology
Design
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Pulmonary circuit
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Artery and vein
Blood to and from lungs
Systemic circuit
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Blood to tissues
Heart design
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Three dimensional hollow mass of muscle
Double pump
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2 receiving chambers - atria
2 pumping chambers - ventricles
Fibrous skeleton
Suspended in fluid filled pericardial sac
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Heart
Anatomy
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4 chambers
AV valves
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Tricuspid
Bicuspid - mitral
Semilunar valves
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Right - pulmonary
Left - aortic
Inferior view of valves
Heart Anatomy
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Pericardium
Heart wall (epicardium, myocardium,
endocardium)
Heart wall
Coronary circulation
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Arteries arise from base of aorta
Venous blood empties into the right atrium
Coronary disease
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1. Angina pectoralis
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Temporary halt in blood delivery
2. Myocardial infarction
 Amitotic myocardium
 Scar tissue formed is non-contractile
Conduction pathway
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Muscle cells modified to conduct electrical
information (myogenic pacemaker)
Autorhythmical cells
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SA node
AV node
Bundle of His
Bundle branches
Purkinje branches
Conduction pathway
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Excitation sequence
Conduction pathway
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Heart rate fluctuations
Sympathetic
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Cardiac nerve
Norepinephrine
(Na+, Ca++ influx)
Parasympathetic
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Vagus nerve
Acetycholine (K+ efflux)
Potentials in conductive
pathway
Na+ permeability
Potentials in conductive
pathway
Potentials in conductive
pathway
Refractory period
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Skeletal muscle - short
Cardiac muscle - long
Refractory period
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What causes it?
Electrocardiograph
Irregular heartbeats
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SA node fires early
Extra heartbeat followed by a pause
Force of
contraction
Time
Ectopic pacemaker
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AV node taking over role of damaged SA node
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Slower heartbeat
No P wave
Ventricles
with greater
contractility
Irregular heartbeat
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Heart block: blockage of conductive pathway
 Slower heartbeat
 Multiple P waves
 Irregular QRS
Fibrillation
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Continuous disorganized AP pattern
APs with decreased refractory period
Cure: defibrillate with high voltage causes
simultaneous refractory period
Cardiac cycle
• Systole/diastole
• Mid-to-late diastole
• Atria and ventricles relaxed
• Ventricles fill 80%
• AV valves open, aortic &
pulmonary
valves closed
• SA node discharge
• EDV
Cardiac cycle
• Ventricular systole
• QRS complex
• AV valves close
• 1st. heart sound
• Isometric pressure build up
• Aortic and pulmonary
valves open
• ESV
• Atrial pressure rises
• Aortic pressure rises
• T wave
• AV valves open, pulmonary
and aortic valves close
• 2nd. heart sound
(dicrotic notch)
Cardiac cycle
• Early diastole
• Atria fill with blood
• AV valves open
• Remember the
aortic and pulmonary
valves are closed
Heart sounds
• Lub
• Turbulent blood flow as a result of
closure of AV valves
• Onset of systole
• Dub
• Turbulent blood flow as a result of
closure of aortic and pulmonary valves
• Onset of diastole
Heart murmurs
• Common
in children
• Adults: irregular turbulent flow through
valves
• Stenosis: narrow valve opening
• Regurgitation: leakage of blood through a
valve
Summary
Ion movement
Heart
sounds
Pressure changes
causes valves
to open and close
Electrical activity
Muscle contraction