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The Muscular System. 3 Types of Muscles A Muscle is Composed of a Variety Of Tissues.

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Presentation on theme: "The Muscular System. 3 Types of Muscles A Muscle is Composed of a Variety Of Tissues."— Presentation transcript:

1 The Muscular System

2 3 Types of Muscles

3 A Muscle is Composed of a Variety Of Tissues

4 Sarcomere – the structural and functional unit of a myofibril

5 The Sarcomere Thin and Thick Filaments

6

7 Muscular Responses Twitch – a brief period of contraction followed by a period of relaxation Phases 1. Latent Period – muscle tension is beginning 2. Period of Contraction Muscle fibers shortening 3. Period of Relaxation Ca 2+ renters the sarcoplasmic reticulum Relaxation – 1.acetylcholinesterase decomposes ACh in the synapse 2. Ca 2+ pump quickly moves Ca 2+ back into sarcoplasmic reticulum

8 Figure 9.14b Latent period Extraocular muscle (lateral rectus) Gastrocnemius Soleus Single stimulus (b) Comparison of the relative duration of twitch responses of three muscles

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10 Summation – The force of individual twitches combines Incomplete tetanus – Ca 2+ increases in sarcoplasm results in quivering response Complete Tetanus – no period of relaxation

11 Treppe

12 The force that a muscle can generate is dependent on the length that it is stretched before stimulation

13 Muscle Fiber Type

14 The force that a muscle develops depends on: 1.The frequency at which individual muscle fibers are stimulated 2.How many fibers take part in the overall contraction - RECRUITMENT

15 Types of Contractions Isotonic Contraction – muscle changes length and moves a load – Concentric contraction – a muscle shortening contraction – Eccentric contraction – a muscle lengthening contraction Isometric contraction – tension in muscle increases but the muscle does not lengthen or shorten

16 Muscle Fatigue Exercise for a long period of time may cause a muscle to lose the ability to contract - FATIGUE Why? 1. decreased blood flow 2. ion imbalances across sarcolemma from repeated stimulation 3. psychological loss of the desire to exercise 4. increase in lactic acid = lowered pH which prevents muscles from responding to stimulation

17 What is a Cramp? A sustained, painful, involuntary muscle contraction Result from decreased electrolyte concentration in extracellular fluid which triggers uncontrolled muscle stimulation

18 Sliding Filament Theory ws/myosin.html ws/myosin.html l/Esp/folder_structure/su/m4/s11/sum4s11_9.htm


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