Download Comparative Vertebrate Physiology

Human Anatomy and
Physiology
Cardiovascular physiology
Design

Pulmonary circuit



Artery and vein
Blood to and from lungs
Systemic circuit

Blood to tissues
Heart design


Three dimensional hollow mass of muscle
Double pump




2 receiving chambers - atria
2 pumping chambers - ventricles
Fibrous skeleton
Suspended in fluid filled pericardial sac

Heart
Anatomy


4 chambers
AV valves



Tricuspid
Bicuspid - mitral
Semilunar valves


Right - pulmonary
Left - aortic
Inferior view of valves
Heart Anatomy


Pericardium
Heart wall (epicardium, myocardium,
endocardium)
Heart wall
Coronary circulation


Arteries arise from base of aorta
Venous blood empties into the right atrium
Coronary disease

1. Angina pectoralis


Temporary halt in blood delivery
2. Myocardial infarction
 Amitotic myocardium
 Scar tissue formed is non-contractile
Conduction pathway


Muscle cells modified to conduct electrical
information (myogenic pacemaker)
Autorhythmical cells





SA node
AV node
Bundle of His
Bundle branches
Purkinje branches
Conduction pathway

Excitation sequence
Conduction pathway


Heart rate fluctuations
Sympathetic




Cardiac nerve
Norepinephrine
(Na+, Ca++ influx)
Parasympathetic


Vagus nerve
Acetycholine (K+ efflux)
Potentials in conductive
pathway
Na+ permeability
Potentials in conductive
pathway
Potentials in conductive
pathway
Refractory period


Skeletal muscle - short
Cardiac muscle - long
Refractory period

What causes it?
Electrocardiogram
Irregular heartbeats


SA node fires early
Extra heartbeat followed by a pause
Force of
contraction
Time
Ectopic pacemaker

AV node taking over role of damaged SA node



Slower heartbeat
No P wave
Ventricles
with greater
contractility
Irregular heartbeat

Heart block: blockage of conductive pathway
 Slower heartbeat
 Multiple P waves
 Irregular QRS
Fibrillation



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