Download Comparative Vertebrate Physiology

Comparative Vertebrate
Physiology
Cardiovascular systems in
vertebrates
Fish

Heart anatomy
Fish

Blood flow pathway
Amphibians

Heart anatomy
(spiral fold)
Blood pathway
(Spiral valve)
Reptiles


Heart anatomy
Ventricle divided into 3 chambers
Reptiles


Blood flow pathway (non-crocodiles)
Advantage during diving
Reptiles

Crocodiles


Heart anatomy
Foramen of Panizza
Reptiles


Blood flow pathway
Advantage during diving
Birds


Heart anatomy
Renal portal shunt
Mammals

Heart anatomy


4 chambers
AV valves


tricuspid, bicuspid
Semilunar valves

aortic, pulmonary
Conduction pathway

Myogenic pacemaker
Conduction pathway

Excitation sequence
Heart rate fluctuations

Sympathetic
parasympathetic
influence
Pacemaker potential
Cardiac action potentials

Amplitude, configuration and duration of AP’s
differ at different sites of the heart
Refractory period

Prolonged
Refractory period

Prolonged Ca++ and K+ permeability
Ectopic pacemaker

Extra heartbeat followed by a pause
Electrocardiogram
Ectopic pacemaker
• Cause: AV node taking over role of damaged SA node
Ectopic pacemaker
• Cause: blockage of conductive pathway
Cardiac cycle
• Systole/diastole
• Mid-to-late diastole
• Atria and ventricles
relaxed
• Ventricles fill 80%
• Aortic and pulmonary
valves closed
• SA node discharge
• 20% filling of
ventricles
• EDV
Cardiac cycle
• Ventricular systole
• QRS complex
• First heart sound
• Isometric pressure
build up
• Opening of aortic
and pulmonary valves
• ESV
• Aortic pressure rises
then falls
• Atrial pressure rises
Cardiac cycle
• Early diastole
• T wave
• 2nd. Heart sound
(closure of aortic and
pulmonary valves,
dicrotic notch)
• AV valves open
• Atria fill with blood
Heart sounds
• Lub
• Caused by closure of AV valves
• Onset of systole
• Dub
• Caused by closure of aortic and pulmonary valves
• Onset of diastole