C.21. - A&P II Lecture Chapter 21 Page 1 of 16 Vascular...

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Instructor-Dr. Wylie Lecture- Chapter 21 Page 1 of 16 Vascular System Function -transports blood between heart, lung, & tissues -exchange of materials between the blood & tissues -major component of blood pressure Blood Pressure - force the blood exerts against the walls of the vessels. Types of Blood Vessels in cardiovascular system Major types of blood vessels are 1. Arteries Distributing vessels Bring blood to the body 2. Capillaries Exchange vessels that distribute blood to the cells 3. Veins Collecting vessels Bring blood back to the heart The pattern of distribution starts with; Arteries à Arterioles à Capillaries à Venules à Veins Arteries “Efferent Vessels” Carry blood away from the heart Carry oxygen rich blood Exception of those in the Pulmonary Circuit Part of Fetal Circulation Blood proceeds to the tissues through 3 sizes Elastic Arteries Muscular Arteries Arterioles 1. Elastic arteries -“conduction arteries” Near the heart Aorta and its major branches Transport large volumes of blood away from heart Largest in diameter and most elastic Contain more elastin than any other type of vessel
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Instructor-Dr. Wylie Lecture- Chapter 21 Page 2 of 16 Tunica media contains the most amount of elastin Elastin enables them to handle large pressure fluctuations Expand when the heart forces blood into them Recoil to propel blood onward into the circulation when the heart relaxes Thick walled Low resistance to blood flow because of large lumen (central opening) 2. Muscular arteries -“distributing arteries” Medium-sized Tunica media contains relatively More smooth muscle and Less elastic tissue than that of elastic arteries Deliver blood to specific body organs Skeletal muscles Internal Organs Account for most of the named arteries Site of Major Pressure Points Areas where a pulse can be felt easily over a superficial artery Artery can be compressed over a bone or firm tissue to control bleeding that is distal to the artery. 3. Arterioles - “Controlling Vessels” Smallest Arterial Branches Largest Content of Smooth Muscle for Size Greatest Cross Sectional Area Bring blood to the capillaries Controls blood flow to capillaries Diameter of each arteriole’s lumen is regulated in 2 ways: 1. Local factors (Conditions) -Low O2 or pH 2. Distant factors -Nervous or Endocrine Example; Sympathetic nervous system adjusts the diameter of arterioles throughout the body to regulate systemic blood pressure 4. Capillarie s - "Exchange Vessels” Only vessel that comes into intimate contact with tissue cells and serve cellular needs One cell layer thick Structure of walls allow permeability Blood moves thru slowly
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This note was uploaded on 07/22/2011 for the course PTA 1001 taught by Professor Rice during the Spring '11 term at South University Online.

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C.21. - A&P II Lecture Chapter 21 Page 1 of 16 Vascular...

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