Muscles and Tissue

Muscles and Tissue

1. Properties

   • Excitability: When a muscle cell is stimulated by the nervous system. Contractility: result of stimulation of muscle cells that cause a contraction where the shortening results in either a pull on bones of the skeleton or movement of a specific body part. Elasticity: contracted muscle cell recoils to a resting state when tension is removed.  Extensibility: extending out the arm for example flexing ones elbow.

2. Skeletal Muscle Tissue

   • Composed of four tissue types; epithelial, connective, muscle and nervous. This muscle is striated and attached to more than one bone. Just one single muscle can be comprised of thousands of fibers.
   • Functions
     • 1. Body movement 2. maintenance of posture3. temperature regulation4. storage and movement of materials Ex) Sphincters or orfices. 5. Support
   • Gross Anatomy
   • Microscopic Anatomy
     • Organization of the sarcomere which is the functional contractile unit of a skeletal muscle fiber.  Motor unit that stimulates muscle contraction.
   • Components of Muscle Fiber
   • Skeletal Muscle Architecture

3. Levers and Joints

   • Classes of Levers

4. Cardiac Muscle

   • The cells of this muscle are striated like skeletal muscle fibers. they are short and thick and have one to two nuclei. They are a y shaped branch and join to adjacent muscles. They also have intercalated discs.  This muscle is found around the heart. It is autorhythmic which means that the cells generate an impulse without nervous stimulation. It is responsible for our heartbeat.  The stimulation comes from calcium ions.  

5. Smooth Muscle

   • found in the hollow organs, for example the intestines. The contraction speed is slow and is involuntary movement. It receives calcium from the sarcoplasmic reticulum and interstitial fluid. There are no myofibrils and it is very regenerative.  The cells are spindle shaped with one nuclei that is centrally located. It also has NO STRIATIONS

6. Disorders

   • Atrophy
     • wasting of tissue which results in reduction of muscle size, tone and power. This effects people who have problems with their nervous system or are paralyzed
   • Fibromyalgia
     • chronic severe pain both in the muscles and the skeleton which also causes fatigue, morning stiffness.  Causes are thought to be stress, anxiety, sleep disturbances and endocrine abnormalities. 
   • Muscular Dystrophy
     • skeletal muscled degeneration and loses strength. It is gradually replaced by adipose and fibrous c.Tissue.  Hereditary
   • Myofascial Pain Syndrome
     • disorder associated with over use of the postural muscles. This results in pain from muscle fibers tightening and twitching. Can also cause sweating and goose bumps.  People between the age of 30-60 yrs old are affected by this disorder. 

7. Muscle Attachments

   • Tendon: attaches muscle to bone, skin or another muscle Aponeurosis: thin flattened sheet of a tendon Origin: less mobile attachment of a muscle Insertion: more mobile attachment of a muscle

8. Rigor Mortis

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