Download - 11.3 Blood Vessels
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11.3 Blood Vessels
Pages 487-494
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Blood Vessels
• 19 000 km
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Arteries
• Carry blood away from the heart3-layers:Outer connective tissue (elastic)Middle muscle layerInner epithelial layer (endothelium)
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Arterioles
• Arteries branch into arterioles
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Controlling blood flow
Vasodilation: Increases diameter of blood vesselIncreased blood flow to the skinCooling strategy
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Controlling Blood Flow
Vasoconstriction• Nerves cause smooth muscle to contract• Narrowing of blood vessel diameter• Restricts blood flow• Response to cold
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Capillaries
• No cell is farther than two cells away from a capillary.
• Blood cells move through them in single file.
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Pre-capillary sphincters
• Relax and increase blood flow during exercise
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Venules and veins
• Return blood to the heart• Less elasticity in the walls• Less smooth muscles in the walls• Valves keep blood flowing in the right
direction
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Varicose veins
• Damaged valves in legs
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Blood pressure
• Sphygmomanometer• Blood pressure cuff• Inflated until blood flow ceases then released• Systolic pressure…heart contracts 120 mmHg• Diastolic pressure…heart relaxed
80 mm Hg
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Hypertension
• High blood pressureDiet, age, weight, activity level, medication are contributors to high blood pressure
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Lymphatic System
• Circulatory system and immune system• Maintains blood volume• Destroys foreign invaders
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Lymph
• Proteins from blood tissue fluidlymph vessels veins
Contains fluid, germs, dead or damaged cells, fat from lacteals of villi
Lymph nodes filter out germs
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Spleen and tonsils
• Spleen filters lymphatic system, reservoir for RBC’s and WBC’s
• Tonsils filter germs/enlarge
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thymus
• Secretes hormones that help lymphocytes, a type of leuknocyte, develop their ability to recognize and attack foreign invaders