Muscular System

Muscular System

1. Skeletal muscles, tendons, ligaments, cartilage, and bones allow us to stand upright and move.

2. The muscular system is constituted by the muscular cells and sheats of connective tissue that cover them and connect the muscular masses with the rest of the locomotor system.

   • Contractile capacity characterizes muscle cells since they have a possibility to shorten their lenght and then return to their original form. They have a capacity to carry out contraction and relaxation.
     • Muscle cells are classified into striated and smooth.
       • Striated includes skeletal and cardiac muscles.
         • Eskeletal striarted muscle fibers are elongated and multinucleated cells of cylindral morphology, with a pattern of transverse striae that are not easy to observe under a microscope.
       • Smooth , the organization of the contractile apparatus is different, so bands are absent when a sample is seen trough a microscope.
       • Sarcmere: Are limited by Z lines or disks. They are formed by a protein called alpha-actinin.
         • The contraction-relaxation cycle begins when cells respond to the nervous stimulus.
           • It releases Ca2 in the smooth endoplasmic reticulum.

3. Without connective tissue, there would be no functional association with the rest of the components of the locomotor system.

   • Tendons connect the muscles with the bones, the ligaments bind the bones to each one.

4. Muscle groups:

   • Agonists on main muscle, produces most of the force during muscle action.
     • Synergist: Helps the main muscle to achieve more power.
       • Antagonist: Opposes the main muscle.
         • Fixer: Prevents a bone from moving to allow the movement of something else.

5. Diseases and injuries:

   • Can cause weakness, pain or paralysis.
     • Muscular dystrophy, myositis, soft tissue sarcoma, sprain, luxation, tear. Cramp is a contraction of a muscle.