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Internal Transport• Gastrovascular
cavity makes circulatory system unnecessary
• Open and closed circulatory systems
• What are the limits an open circulatory system places on an organism?
• What is the difference between an artery and a vein?
• Arteries carry blood away from the heart
• Veins bring blood back to the heart
• Why do veins have valves and arteries do not?
• Veins move blood against gravity without benefit of the heart contraction
• Blood flow:– Heart arteries arterioles
capillaries venules veins heart
• Which chamber of the heart receives the blood?
• Which chamber pumps the blood?
Vertebrate Circulatory Evolution• Fish have 2 chambered heart, one beat circuit:
– 1 atrium– 1 ventricle
• Amphibians have 3 chambered heart:– 2 atria– 1 ventricle
• Reptiles have 3 – 4 chambered heart:– Septum keeps 2 parts of ventricles separate
• Mammals and birds have 4 chambered heart!
The Heart• Cardiac muscle• Atria have thin walls• Ventricles have thick and powerful walls• Systole = ventricular contraction blood is
pumped• Diastole = ventricular filling• Lub dub = heart sounds opening and closing
of the valves– Lub = contraction of ventricles (AV closing)– Dub = blood recoiling against SL valves
• Heart murmur = valve defect
• CO = cardiac output ; – Volume of blood pumped/ minute
• SV = stroke volume:– Amount of blood pumped by L
ventricle/contraction
• CO is effected by heart rate and SV
• Myogenic heart can regulate its own rhythm
• SA node is the pacemaker of the heart
Arteries and Veins• How do differences between arteries and
veins reflect their different functions?
• Artery wall is very thick to absorb pulsation from heart
• Veins are wider in diameter and are not as muscular
• Veins have valves
• Capillaries have only single layer of endothelium
Blood Pressure• The force that blood exerts against
vessel walls
• BP is greater in arteries than veins
• Pulse is measure of BP
• Exact BP is measured as systolic/diastolic pressures
• Constricted blood vessels have higher BP than dilated vessels
• In veins heart has little effect on BP
• How, then does blood move in veins?
Blood Flow
Velocity
Blood Flow Through Capillary
Beds
Capillary Movement of Fluids
Lymphatic System
• Lymphatic system returns lost blood to circulatory system
• Lymph nodes filter the lymph
• Help fight infection
Blood Smear
Blood Clot
Heart disease
• Atherosclerosis • Strokes• Blockage• Bypass
How can 1 heartbeat circulate
blood through 2 capillary
beds?
What are the advantages and disadvantages of the amphibian
circulatory system?
• What is the change seen in reptiles that was not present in amphibians?
Why do endotherms have the greatest need for a 4
chambered heart?
Birds and mammals show convergent evolution of 4 chambered heart!