BI13_Ch9 Text Notes


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ANATOMY AND PHYSIOLOGY 1 TEXT NOTES Chapter 9 – Muscles and Muscle Tissue 1. OVERVIEW OF MUSCLE TISSUES a. Types of Muscle Tissue i. Three types of muscle tissue: skeletal, cardiac, and smooth. ii. Muscle Fibers – term for skeletal and smooth muscle cells because they are elongated. iii. Muscle contraction depends on two kinds of myofilaments. iv. The prefixes myo or mys (meaning “muscle”) or sarco (meaning “flesh”) refer to muscle. v. Skeletal Muscle – are the longest muscle cells; have obvious striations; and can be voluntarily controlled. 1) Skeletal muscle is also called voluntary muscle . 2) Skeletal muscle is responsible for overall body movement. It can contract rapidly, but tires easily. vi. Cardiac Muscle – are striated, but not voluntary. Lecture Notes: Uninucleated and binucleated cells. Intercalcated discs – where cells are connected by desmosomes and gap junctions. Controlled by pacemaker cells. vii. Smooth Muscle – found in the walls of hollow visceral organs (ex. stomach, urinary bladder). It has no striations and is not subject to voluntary control. 1) It forces substances through the body; and its contractions are slow and sustained. b. Functional Characteristics of Muscle Tissue i. Excitability (Responsiveness or Irritability) – ability to receive and respond to a stimulus. In the case of muscle, the stimulus is usually a chemical. ii. Contractility – ability to shorten forcibly when adequately stimulated. iii. Extensibility – ability to be stretched or extended. iv. Elasticity – ability of a muscle fiber to recoil and resume its resting length after being stretched. c. Muscle Functions i. Muscle performs four functions for the body: movement, maintain pressure, File: a3f2e7b06e283f55895d885b1753e0470f982a82.doc Updated: 8/14/09
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Chapter 9 Page 2 stabilizes joints, and generates heat. ii. Producing Movement (no notes from this section) iii. Maintaining Posture (no notes from this section) iv. Stabilizing Joints (no notes from this section) v. Generating Heat 1) Muscles generate heat as they contract. 2) Skeletal muscle accounts for a least 40% of body mass. vi. An additional function of skeletal muscles is to protect fragile internal organs by enclosure. vii. Smooth muscle also forms valves to regulate the passage of substances through internal body openings. 2. SKELETAL MUSCLE a. Gross Anatomy of a Skeletal Muscle Lecture Notes: Smallest blood vessels in the body. Vessels are long, branched, and extensively cross-linked. i. Each skeletal muscle is a discrete organ made up of several kinds of tissue. ii. Nerve and Blood Supply 1) In general, each muscle is served by one nerve, and artery, and by one or more veins, all of which enter or exit near the center of the muscle. 2)
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This note was uploaded on 08/12/2009 for the course BI 13 taught by Professor Alexasawa,ph.d during the Spring '09 term at College of the Desert.

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