CIRCULATORY copy - CIRCULATORY Circulatory System =...

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CIRCULATORY Circulatory System = functions as transport system of body, picks up oxygen from respiratory structures, nutrients from digestive tract, hormones from endocrine glands, and other needed materials such as antibodies, transports them to tissues, and then returns CO 2 , nitrogenous waste, and other excess substances in the interstitial fluid to site of removal from body Important Circulatory System Roles (3): 1. Thermoregulation = transport of metabolic heat through body o Evolved mechanisms – shunt blood toward/away from body parts that need to be heated/cooled 2. Coagulants (in blood) – necessary to stop bleeding at injured sites 3. Transport of antibodies (and other substances) – important to protect body from pathogens 2 Divisions of Circulatory System: Blood-Vascular System and Lymphatic System Blood-Vascular system = includes components of blood, vessels, heart o Blood – composed of liquid plasma (90% water, plasma proteins – ex. Albumin, Globulin), and number of cell types 3 categories of blood cells: 1. Erythrocytes (red) – nucleated (most vertebrates), non-nucleated (vertebrates) – contain hemoglobin – binds with oxygen transports to tissue 2. Leukocytes (white) – main function = defense of body by engulfing/ destroying foreign particles, releasing histamine to aid in inflammatory reactions, initiating immune responses 3. Thrombocytes (platelets) – circulating cell fragments, initiate blood clotting o Vertebrates = closed circulatory system, blood confined in blood vessels 2 types of blood vessels: 1. Arteries = carry blood from heart to capillary networks in tissues, high oxygen content blood (except pulmonary) o Walls relatively thick – very muscular layer, elastic – allow for expansion when blood pumped into, recoil – keep blood flowing o Branch into smaller Arterioles = large amount smooth muscle Capillaries = wall only consisting of endothelium, gas exchange here between blood, interstitial fluid Diameter of vessels decrease – vessel number increased combine cross-sectional area increased (770 times aorta) Flow rate greatly decreased, more time available for diffusion of materials between blood, interstitial fluid 2. Veins = return blood back to heart, low oxygen content blood (except
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pulmonary) o Capillaries Venules – decreasing in combined surface area, flow rate increases Veins – thinner walls, larger than arteries Smooth muscle lining arteries/veins – important role in blood distribution in body o Autonomic nervous system/hormone control – smooth muscle vessel lining contract or relax depending on signal type Contract smooth muscle shortens vessel diameter decreases - Vasoconstriction diameter decrease + resistance increase = blood diverted through other vessels Relax diameter increases response = Vasodilatation diameter increase + pressure decrease = flow through vessel increases
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This note was uploaded on 04/29/2010 for the course BIOL 1404 taught by Professor Machaeldini during the Fall '09 term at Texas Tech.

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CIRCULATORY copy - CIRCULATORY Circulatory System =...

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