Transcript Heart and Blood Vessels

HEART AND BLOOD VESSELS
BLOOD VESSELS
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Arteries
From heart to tissue
 Usually carry oxygenated blood
 Branch into arterioles
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Veins
From tissues back to heart
 Usually carry deoxygenated blood
 Venules
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Capillaries
Small, thin
 Allow diffusion into tissues
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ARTERIES & ARTERIOLES
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3 layers of tissue
Endothelium
 Connective tissue and smooth muscle
 Connective tissue with elastic/collagen fibers
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Smooth muscles in arterioles control blood
pressure and volume of blood to tissues:
Vasoconstriction
 Vasodilation
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Exercise increases vasodilation in arterioles of
muscles
VEINS AND VENULES
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Blood flows from capillaries to venules to veins
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Large diameter, some smooth muscle
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Pressure is lower, farther from heart
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Valves prevent back flow
HEART
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Basic Structure:
Atrium – receiving chamber
 Ventricle – pumping chamber
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Evolution
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Fish
1 atrium, 1 ventricle
 Single circuit of blood vessels
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Amphibians, Most Reptiles
2 atria, 1 ventricle
 Double circuit
 Conus arteriosus separates oxygen rich & poor blood
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HEART, CONT.
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Birds, Mammals & crocodilians
2 atria, 2 ventricles
 Conus arteriosus  aorta & pulmonary arteries
 Ventricle separated by septum
 Double circuit
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http://trc.ucdavis.edu/biosci10v/bis10v/media/ch2
2/circulatory_systems.html
http://trc.ucdavis.edu/biosci10v/bis10v/media/ch2
2/blood_circulation.html
HUMAN HEART
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Hollow, muscular organ
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Cardiac Muscle
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Enclosed by the pericardium
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Septum separates left and right sides of heart
In fetal heart, foramen ovale allow blood to flow from
right to left atrium
 Why??
 Closes and leaves fossa ovalis
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HEART VALVES
AV valves
Right – tricuspid
 Left -mitral valve or bicuspid
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Chordae tendinae hold valves in place
As blood enters atria, pressure forces valves to
open
As ventricles contract, back pressure forces
valves closed
HEART VALVES, CONT.
Semilunar valves
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Exit from heart
Aortic
Pulmonary
As ventricles contract, valves open
As ventricles relax, blood pressure in arteries is
higher, valves close
http://www.bostonscientific.com/templatedata/im
ports/HTML/CRM/heart/interact_4.html
PATTERN OF CIRCULATION
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Vena cava returns blood from
body to heart
Right atria, right ventricle to
pulmonary artery
Lungs  gas exchange
Pulmonary vein to left atrium to
left ventricle
Aorta to body
YOUR HEART IN ACTION
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http://www.bostonscientific.com/templatedata/im
ports/HTML/CRM/heart/interact_6.html