Muscular system bookwork—KEY

Short Answer #2, 7, 10, 12, 18, 20, 21

2.

Microscopic Anatomy / Location / Arrangement / Function
Skeletal / Striated, multi-nucleated, unbranched long fiber / Attached to bones / Bundled, wrapped in connective tissue / Voluntary contraction in response to neural stimulation
Smooth / Unstriated, spindle shaped, one nucleus / Lining of visceral organs / Circular and longitudinally bilayer / Involuntary; moves food/substances through the body
Cardiac / Striated, single nuclei / Heart / Spiral bundles / Steady coordinated involuntary contraction to move blood thru body
  1. Ach leads to contraction:

Ach attaches to receptors on sarcolemma which alters the sarcolemma’s ability to regulate Na+/K+ permeability. As the Na+ rushes into the cell, this causes an action potential across the muscle cell, and the sarcoplasmic reticulum dumps Ca+2 into muscle cell. The Ca+2 binds to the troponin, moving both it and tropomyosin off of the myosin binding site (found on actin fiber but usually blocked by troponin/tropomyosin). ATP is hydrolyzed by the presence of Ca+2 which provides the energy for the myosin head to pivot. This steps the actin filament into the center of the cell until contraction is complete or Ca+2 is taken back up by the sarcoplasmic reticulum (which in turn allows the troponin/tropomyosin to knock the myosin head off the actin fiber)

  1. Origin = non moveable

Insertion = moveable

12. Prime mover does most of the work, synergist stabilizes or assists. Primer mover as an antagonist is when the prime mover reverses the action of the opposing muscle.

18. Hamstring: primary function is to lengthen the quadriceps muscles, which causes the action of flexing the knee and extending the hip. The quadriceps extend the knee and flex the hip; lengthening the hamstrings

20. Exercised muscles are healthy and firm. Vigorous exercise increases the size of cell (increasing the number of filaments). If a muscle is not used, it will atrophy, becoming soft and flabby.

21. Aging leads to decreased amounts of muscle tissue and increased amount of connective tissue. The muscles therefore become stringy and will lose muscle strength.

At the Clinic: 2, 5, 6

2. Ruptured achille’s (gastrocnemia) tendon

5. This pesticide will prevent the neurotransmitter from degrading; therefore, the muscles are continuously called on to contract.

6. Your abdominal muscles flex the spine (specifically it’s the obliques) so weakness on one side will result in an imbalance and will cause scoliosis.