PCC BIO 160IN - Lesson 6 - The Muscular System (8 pages)

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Lesson 6 - The Muscular System



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Lesson 6 - The Muscular System

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Pages:
8
School:
Pima Community College
Course:
Bio 160in - Intro Human Anatomy & Phys
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BIO 160 Introduction to Human Anatomy and Physiology Biology 160 Pima Community College Downtown Campus LAB SIGN OFF PAGE Lesson 5 CHAPTER 6 Name Please staple all of your lab pages for this Chapter together with this page as the top You will use this page to get your Labs for the Chapter signed off by the Biology Learning Center staff You need to have all of the following steps initialed by a staff member before you can be allowed to take the Chapter Exam After you have obtained all of your sign offs for this Chapter be sure that a BLC staff member indicates on your Lab Card that you are OK to take the Chapter Exam Also keep this sign off page along with your completed lab worksheets as proof of your lab completion If your Lab Card indicates that you have not completed the required Labs for this Chapter and you feel that you have it is up to you to provide proof that you have indeed done the Labs Keep this page Muscles and movements Electromyography 10 2 14 1 BIO 160 Introduction to Human Anatomy and Physiology Lesson 6 The Muscular System Overview of Muscle Tissues What are the 3 types of muscle tissue 1 2 3 Which type of muscle tissue is not striated Which type of muscle tissue is comprised of long fibers with numerous nuclei In which type of muscle do branched cells connect to each other by intercalated discs Which type of muscle tissue is voluntary Where is the one place cardiac muscle is located Name two places where you find smooth muscle and Skeletal muscle tissue is wrapped in connective tissue to give it greater strength A single muscle fiber is wrapped in the endomysium A group of muscle fibers are called a fascicle and they are wrapped in the The whole muscle is wrapped in the and around that is fascia Muscles connect to bones primarily by means of Name 4 functions of muscle 1 2 3 4 Microscopic Anatomy of Skeletal Muscle The plasma membrane of a muscle fiber is called the The cytoplasm of a muscle fiber is filled with myofibrils Perfectly aligned myofibrils give skeletal muscle fibers their striated appearance The dark bands are called bands The light bands are called bands Each myofibril is comprised of two types of protein called myofilaments The thick myofilaments are called The thin myofilaments are called 10 2 14 2 BIO 160 Introduction to Human Anatomy and Physiology The sarcomere is the contractile unit of muscle and is composed of overlapping myofilaments Each sarcomere extends from Z disc to Z disc Thousands of sarcomeres line up in a row the length of a myofibril In one sarcomere myosin extends the length of the A band The Z disc is in the middle of the I band and is the anchoring place for actin The H zone of the sarcomere is also called the bare zone when the muscle is at rest When the muscle contracts the actin slides on the myosin and the bare zone decreases and can disappear Muscle fibers have a specialized endoplasmic reticulum called the and their function is to store calcium ions and to release it on demand when the muscle fiber is stimulated to contract Skeletal Muscle Activity Skeletal muscle must be stimulated by nerve impulses to contract A motor unit is one and all of the muscle fibers innervated by it A motor neuron reaches the muscle fibers by way of a long axon that branches into a number of axon terminals Each axon terminal forms a junction with a muscle fiber at a junction The is the space between the axon terminal of the neuron and the muscle cell The two membranes do not touch and there is interstitial fluid in the synaptic cleft When a nerve impulse reaches the axon terminal the neurotransmitter is released The acetylcholine travels across the synaptic cleft and connects with acetylcholine Following the binding of acetylcholine to the acetylcholine receptors the sarcolemma becomes permeable to sodium ions Na Na rushes into the cell followed by rushing out of the cell The movement of ions causes a depolarization followed by a repolarization of the sarcolemma called an action potential The action potential travels the length of the The action potential travels to the interior of muscle fiber by T tubules The action potential in the T tubules triggers the release of calcium ions from the sarcoplasmic reticulum Calcium ions bind to the actin molecules Crossbridges form between actin and myosin molecules This is done repetitively causing the muscle fiber to shorten Individual muscle fibers contract in an all or none manner Each action potential stimulates a muscle fiber to contract maximally There are no partial contractions of muscle fibers 10 2 14 3 BIO 160 Introduction to Human Anatomy and Physiology Whole muscles contract in a manner There are different degrees of contraction for a whole muscle A twitch is a single muscle contraction followed by its relaxation Tetanus occurs when the muscle contracts again before completely relaxing There is a of contractions as they get progressively stronger with stimulation Complete tetanus is a sustained muscle contraction when there is no relaxation between contractions Muscle force depends on the number of contracting Initially muscles use ATP as an energy source There is only 4 6 second s worth of stored ATP to contract a muscle When ATP runs out a muscle fiber first turns to to generate more ATP Creatine phosphate supplies are diminished in seconds Aerobic respiration occurs in the and generates 36 ATP per glucose molecule As glucose is broken down into CO2 and H20 energy is released Aerobic respiration requires a continuous supply of The muscles use aerobic respiration when the body is at rest and during light exercise Aerobic conditioning develops the aerobic respiratory capacities of muscles During vigorous exercise the muscles turn to anaerobic respiration Anaerobic respiration is faster than aerobic respiration but is much less efficient and produces only 2 ATP per glucose molecule Glucose is broken down only as far as pyruvic acid and a large amount of is produced which causes muscle fatigue Oxygen dept occurs during prolonged muscle activity and in short bursts of intense physical activity If you are breathing hard you are in oxygen debt You are trying to get more oxygen to your muscles by breathing hard The oxygen is required for restoring resting ATP and CP to resting levels and to help process the accumulated lactic acid Oxygen dept is a common cause of muscle In isometric contractions there is no movement involved The amount of tension increases but the length of the muscle does not


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