MSU BIO216 Lecture - Week 4-5 Objective Assignment

MSU BIO216 Lecture - Week 4-5 Objective Assignment -...

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BIOL216 Lecture Week 4-5 Objective Assignment Chapter 19: The Cardiovascular System: Blood Vessels PART 1: OVERVIEW OF BLOOD VESSEL STRUCTURE AND FUNCTION 1. Describe the three layers that typically form the wall of a blood vessel, and state the function of each. The wall of an artery consists of three layers. The innermost layer, the tunica intima, contains simple squamous epithelium, basement membrane and connective tissues. The epithelium is in direct contact with the blood flow. The middle layer, the tunica media, is primarily smooth muscle and is usually the thickest layer. It not only provides support for the vessel but also changes vessel diameter to regulate blood flow and blood pressure. The outermost layer, which attaches the vessel to the surrounding tissue, is the tunica externa or tunica adventitia. This layer is connective tissue with varying amounts of elastic and collagenous fibers. The connective tissue in this layer is quite dense where it is adjacent to the tunic media, but it changes to loose connective tissue near the periphery of the vessel. 2. Define vasoconstriction and vasodilation. Vasoconstriction is the narrowing (constriction) of blood vessels by muscles in their walls. When blood vessels constrict, the flow of blood is restricted or slowed. Vasodilation is the widening of blood vessels resulting from relaxation of the muscular wall of the vessels. What widens is actually the diameter of the interior (the lumen) of the vessel. Vasodilation is the opposite of vasoconstriction. 3. Describe the structure and function of a capillary bed. Capillaries, the smallest and most numerous of the blood vessels, form the connection between the vessels that carry blood away from the heart (arteries) and the vessels that return blood to the heart (veins). The primary function of capillaries is the exchange of materials between the blood and tissue cells. Capillaries do not function independently; instead, they tend to form interweaving networks called capillary beds. The flow of blood from an arteriole to a venule through a capillary bed is called microcirculation. Capillary beds consist of two types of vessels - a vascular shunt and true capillaries. In addition to forming the connection between the arteries and veins, capillaries have a vital role in the exchange of gases, nutrients, and metabolic waste products between the blood and the tissue cells. Substances pass through the capillaries wall by diffusion, filtration, and osmosis. Oxygen and carbon dioxide move across the capillary wall by
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This note was uploaded on 05/07/2010 for the course BIOLOGY BIO 216 taught by Professor Tucker during the Spring '10 term at Mountain State.

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MSU BIO216 Lecture - Week 4-5 Objective Assignment -...

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