CHAP21_2402 - BIOLOGY 2402 Anatomy and Physiology CHAPTER...

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Unformatted text preview: BIOLOGY 2402 Anatomy and Physiology CHAPTER 21 THE CARDIOVASCULAR SYSTEM: BLOOD VESSELS AND HEMODYNAMICS THE CARDIOVASCULAR SYSTEM: BLOOD VESSELS AND HEMODYNAMICS Hemodynamics- A study of the force involved in circulating blood throughout the body. Blood-Life line Heart-Pumps Vessels-Direct/distribute GENERAL FEATURES OF BLOOD VESSEL STRUCTURE (Blood vessels form a Network (Closed System) of tubes that carry blood away from the heart, transport it to the tissues of the body, and then return it to the heart.) Arteries- Vessels that carry blood from the heart to the tissues. Arterioles- Smallest branches of arteries. (Medium-sized arteries divide into smaller arteries, which, in turn divide into smaller arteries called arterioles.) Capillaries- countless microscopic vessels formed as branches of Arterioles as they enter a tissue. Venules- small veins formed as groups of capillaries reunite before leaving the tissue. Veins- blood vessels that convey blood from the tissues back to the heart. (Formed by merged venules results to progressively larger tubes called veins). *Vasa Vasorum- Blood vessels on the walls of blood vessels. (Blood C h a p t e r 2 1 3 vessels require oxygen and nutrients just like other tissues of the body.) ARTERIES Structure 1) Found empty at death, were thought to contain only air. Lumen- Is the hollow center through which blood flows. 2.) Three coats or tunics: a) Tunica Intima- Inner Coat - simple squamous epithelium 1) Endothelium 2) Basement Membrane 3) Internal Elastic Lamina b) Tunica Media- Middle coat 1) External elastic lamina 2) Smooth muscle c) Tunica Adventitia- Outer coat 1) Elastic fiber 2) Collagen fiber The smooth muscle of arteries is arranged circularly around the lumen. Usually, when there is an increase in sympathetic stimulation, the smooth muscle contracts, squeezes the wall around the lumen, and narrows the vessel. Vasoconstriction- Is a decrease in the size of arterial lumen due to contraction (of the smooth muscle in Tunica Media) Vasodilation- an increase in size of arterial lumen due to relaxation (of the smooth muscle) C h a p t e r 2 1 4 *The contractility of arteries also serves a function in stopping bleeding. Types: 1. Elastic (Conducting) Arteria- Large arteries, serve as a pressure reservoir. - Aorta and Brachiocephalic - Common Carotid - Subclavian - Vertebral - Common Iliac 2. Muscular (Distributing) Arteries- Medium-sized arteries, are capable of greater vasoconstriction. - axillary - mesenteric - brachial - femoral - radial - popliteal - intercostal - tibial - splenic *Anastomosis- Is the union of the branch of two or more arteries supplying the same body region. (Most parts of the body receive branches from more than one artery. In such areas the distal ends of the vessels unite,) -(Anastomoses between arteries provide alternate routes by which blood can reach a tissue or organ --if a vessel is occluded by disease, injury, or surgery.) *Collateral Circulation- the alternate route of blood to a body part through an anastomosis....
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This note was uploaded on 03/10/2012 for the course BIOL 2403 taught by Professor Campbell during the Spring '12 term at Texas Pan American.

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CHAP21_2402 - BIOLOGY 2402 Anatomy and Physiology CHAPTER...

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