Transcript Circulatory System

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
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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
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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!