MUSCULAR SYSTEM 1

• smallest muscle

  stapedius
• largest muscle

  gluteus maximus
• there are about 650 muscles in the body
• Contraction of the skeletal muscles is responsible for the overall movements of the body such as walking, running, or manipulating objects with hands

  body movement
• Skeletal muscles constantly maintain tone, which keeps us sitting or standing erect.


  maintenance of posture
• Muscles of the thorax are responsible for the movements necessary for respiration.

  respiration
• When skeletal muscles contract, heat is given off as a by-product. This released heat is critical to the maintenance of the body temperature.

  production of body heat
• normal body heat

  36-37 degrees celsius
• fever body heat

  38 degrees celsius
• mild fever body heat


  37.5 degrees celsius
• Skeletal muscles are involved in all aspects of communication such as speaking, writing, typing, gesturing, and facial expression.


  communication
• The contraction of smooth muscle within the walls of internal organs and vessels cause constriction of those structures. 


  constriction of organs and vessels
• The contraction of cardiac muscle causes the heart to beat, propelling blood to all parts of the body.


  heart beat
• 
  

  functions of muscular system

  1. body movement
  2. maintenance of posture
  3. respiration
  4. production of body heat
  5. communication
  6. constriction of organs and vessels
  7. heart beat
• muscle action: Are controlled consciously. Like walking or lifting.

  voluntary
• muscle action: Occur automatically, without conscious control. Like Breathing or digesting food.

  involuntary
• Present in our body parts such as the hands, legs, tongue

  striated
• Control the movement of food in the alimentary canal, the contraction and relaxation of blood vessels.

  non-stariated
• 
  

  types of muscle tissue

  1. skeletal
  2. smooth
  3. cardiac
• Muscles attached to the bones enable movement and maintain posture. 


  skeletal muscle
• attached to bones

  skeletal muscle
• Constitutes to about 40% of the body’s weight. responsible for locomotion, facial expressions, posture, respiratory and other body movements


  skeletal muscle
• appearance: Striated, Long and Cylindrical, with nuclei (peripherally located).

  skeletal muscle
• Most widely distributed type of muscle in the body.

  smooth muscle
• Found in walls of hollow organs

  Such as stomach and uterus and tubes (blood vessels and ducts of certain glands.) It is also found in the iris of the eye for pupil dilation.

  smooth muscle
• Appearance: Non-striated, Spindle Shaped, and with nuclei (centrally located)


  smooth muscle
• Found only in the heart.

  Appearance: Cylindrical, Branched, Striated, and with nuclei (centrally located)

  cardiac muscle
• Cardiac muscle and some smooth muscles can contract spontaneously and rhythmically, unlike skeletal muscles, this property is called autoryhthmicity
• 4 functional property of muscle tissue

  1. contractility
  2. excitablity
  3. extensibility
  4. elasticity
• is the ability of muscle to shorten forcefully, or contract.

  Example: Lifting this textbook requires certain muscles to contract

  contractility
• is the capacity of muscle to respond to an electrical stimulus.

  excitability
• means a muscle can be stretched beyond its normal resting length and still be able to contract.

  • Example: You stretch to reach a dropped pencil, your muscles are longer than they are normally

  extensibility
• is the ability of muscle to spring back to its original resting length after it has been stretched.

  elasticity
• Each skeletal muscle is a complete organ consisting of cells, called skeletal muscle fibers associated with smaller amounts of connective tissue, blood vessels, and nerves.
• A muscle is composed of numerous visible bundles called muscle fascicles.
• Fascia is a general term for sheets of dense irregular collagenous connective tissue within the body
• Each fasciculus is surrounded by a connective tissue layer called the perimysium
• The entire muscle is surrounded by a layer of dense irregular collagenous connective tissue called the ­ epimysium
• Muscular fascia is located superficial to the epimysium and separates individual muscles or groups of muscles.
• Skeletal muscles have a rich supply of blood vessels and nerves