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Blood Vessels

Blood Vessels. Ch. 21. Vessels. Arteries Strong elastic vessels that carry blood away from the heart Smallest ones are called arterioles – connect to capillaries Veins Thinner, less muscular vessels that carry blood toward the heart

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Blood Vessels

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  1. Blood Vessels Ch. 21

  2. Vessels • Arteries • Strong elastic vessels that carry blood away from the heart • Smallest ones are called arterioles – connect to capillaries • Veins • Thinner, less muscular vessels that carry blood toward the heart • Smallest ones are called venules – connect to capillaries • Contain valves • Capillaries • Penetrate nearly all tissues • Walls are single-layered squamous cells • Very thin • Function: allow gas/nutrient/waste exchange

  3. Control of Blood Flow • Precapillary sphincters • Circular, valve-like muscle at arteriole-capillary junction • Vasoconstriction • Narrowing blood vessels’ lumen (passageway) • Vasodilation • Expanding blood vessel’ lumen

  4. Control of Blood Flow • Through veins – very inefficient • Slow, weak arteriole pushing doesn’t help much • What helps • Contraction of diaphragm • Pumping action of skeletal muscles • Valves

  5. Blood Pressure • Average is 120/80 (systolic/diastolic)

  6. Major Blood Vessels • Aorta – largest artery, leaves heart from LV • Ascending aorta, aortic arch, descending aorta, abdominal aorta • Pulmonary Trunk • Leaves RV • Splits left and right and lead to lungs • Pulmonary Veins • Return blood from lungs to heart • Connects to LA • Superior and inferior vena cava • return blood from head (superior) and body (inferior) to the heart • Connects at RA

  7. Disorders • MVP – mitral valve prolapse – mitral valve doesn’t close all the way; creates a clicking sound at the end of the cardiac cycle • Heart murmurs – valves do not close completely; causing a harmless sound

  8. Disorders • Myocardial infarction – a blood clot obstructs a coronary artery – commonly called a heart attack • Hypertension – high blood pressure, force within arteries is too high

  9. Disorders • Atherosclerosis • Deposits of fatty materials (cholesterol) which form a plaque and block blood flow • Treatment: • Insertion of catheter and balloon to open the vessels • Can also do a bypass • Vein is inserted to replace the artery to supply blood to the heart

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