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Anatomy & Physiology.  600 muscles that make up 40-45% of your body weight  Made up of bundles of muscle fibers (long, slender cells) held together.

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Presentation on theme: "Anatomy & Physiology.  600 muscles that make up 40-45% of your body weight  Made up of bundles of muscle fibers (long, slender cells) held together."— Presentation transcript:

1 Anatomy & Physiology

2  600 muscles that make up 40-45% of your body weight  Made up of bundles of muscle fibers (long, slender cells) held together by connective tissue  When stimulated by nerves they contract (become short and thick) which causes movement

3  Excitability-the ability to receive and respond to a stimulus  Contractility-the ability to shorten  Extensibility-the ability to be stretched  Elasticity-the ability to resume resting length after being stretched  Automaticity-the ability of a muscle to contract without a nerve supply

4  Movement ◦ Locomotion/manipulation ◦ Heartbeat ◦ Moving substances through hollow organs  To hold the body erect/posture  Body heat – 85% of body heat  Joint stabilization  Some Internal organ protection

5 Cardiac, Visceral/smooth, & Skeletal

6  Skeletal ◦ Striated ◦ Voluntary  Smooth – unstriated – involuntary - visceral ◦ Found in hollow organs like - digestive tract, blood vessels, and ducts leading from glands. ◦ Purpose is to move fluids through these structures  Cardiac ◦ Myocardium ◦ Like striated muscle in appearance but like smooth muscle in function.


8  Forms walls of the heart  Contracts to circulate the blood  Striated with lots of mitochondria  Involuntary  Efferent nerves control the rate of contraction  Afferent nerves sense pain, spasm, & stretch  Contracts at a steady rate, except for brief, rapid bursts

9  Found in the internal organs  Walls of hollow, visceral organs  No striations  Involuntary  Efferent neurons are less important  Afferent nerves are concerned with pain, spasm, and stretch  Steadies constant contractions, automaticity

10  40% of the body  Attaches to and cover the bony skeleton  Longest fibers  Striated  Voluntary  Efferent nerves send impulses for contraction  Afferent nerves send message to inform brain of degree of contraction  Contracts rapidly, tires easily; tremendous power, adaptable  Causes body movement


12 ◦ Strong, tough connective tissue cord ◦ Example  Achilles tendon-attaches the gastrocnemius muscle on the calf of the leg to the heel bone

13  A tough, sheet-like membrane  Covers and protects tissues  Example-lumbodorsal fascia which surrounds the deep muscles of the trunk & back

14  Flat sheet of fibrous connective tissue that connects muscle to bone or to other tissues


16  When muscles attach to bones, one end becomes the origin and one end becomes the insertion  Origin – the end that does not move; usually proximal to insertion. Where the muscle begins.  Insertion – the end that moves when muscle contracts. Where the muscle ends.


18  Steady partial contraction is present at all times  State of tension when awake  State of readiness to act; enables muscles for immediate response  Does not produce an active movement  Keeps muscles firm and healthy  Stabilizes the joints  Maintains posture

19  Loss of muscle tone ◦ Can occur in severe illnesses such as paralysis & palsy ◦ When muscles are not used for a long period of time – atrophy, waste away (degeneration & loss of mass) ◦ Complete immobilization of muscle (complete bed rest or in a cast or loss of neural stimulation) – strength decreases 5% per day; paralysis=atrophy to ¼ the initial size; muscle tissue is replaced by fibrous connective tissue – muscle rehab is impossible; delayed with electrical stimulation

20  Lack of use can result in contracture (permanent contraction of the muscle due to spasm or paralysis) ◦ Severe tightening of a flexor muscle ◦ Results in bending of a joint ◦ Fingers, wrists, and knees, as well as other joints can be affected

21  Muscle fatigue ◦ Muscle is unable to contract ◦ Tension drops to zero  Spasm – sudden involuntary contraction of a muscle  Clonic – a spasm alternating with relaxation  Tonic – sustained

22  Tetanus – a smooth, sustained contraction  Tetany – the result of low calcium ◦ Increases the excitability of neurons ◦ Loss of sensation, muscles twitching, convulsions ◦ If untreated-spasms of the larynx, respiratory paralysis, and death can occur

23  Kinesiology ◦ Muscles work in antagonistic pairs  Biceps brachii – elbow flexion  Triceps brachii – elbow extension ◦ Contraction and relaxation ◦ Muscle innervation  neuromuscular

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