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11.3 Blood Vessels. Pages 487-494. Blood Vessels. 19 000 km . Arteries. Carry blood away from the heart 3-layers: Outer connective tissue (elastic) Middle muscle layer Inner epithelial layer (endothelium). Arterioles. Arteries branch into arterioles. Controlling blood flow.
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11.3 Blood Vessels Pages 487-494
Blood Vessels • 19 000 km
Arteries • Carry blood away from the heart 3-layers: • Outer connective tissue (elastic) • Middle muscle layer • Inner epithelial layer (endothelium)
Arterioles • Arteries branch into arterioles
Controlling blood flow Vasodilation: Increases diameter of blood vessel Increased blood flow to the skin Cooling strategy
Controlling Blood Flow Vasoconstriction • Nerves cause smooth muscle to contract • Narrowing of blood vessel diameter • Restricts blood flow • Response to cold
Capillaries • No cell is farther than two cells away from a capillary. • Blood cells move through them in single file.
Pre-capillary sphincters • Relax and increase blood flow during exercise
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
Varicose veins • Damaged valves in legs
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
Hypertension • High blood pressure Diet, age, weight, activity level, medication are contributors to high blood pressure
Lymphatic System • Circulatory system and immune system • Maintains blood volume • Destroys foreign invaders
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
Spleen and tonsils • Spleen filters lymphatic system, reservoir for RBC’s and WBC’s • Tonsils filter germs/enlarge
thymus • Secretes hormones that help lymphocytes, a type of leuknocyte, develop their ability to recognize and attack foreign invaders