Chapter 6 : The Muscular System
Muscles produce movement or generate tension
Can generate heat (contraction of muscles accounts for ¾ of generated heat !)
40% M/ 32%F body weight = muscles
3 types : SKELETAL // CARDIAC // SMOOTH
Fundamental activity of muscle = CONTRACTION
1. Musles are Exitable : contract in reaction to chemical and/or electrical signals
2. One basic mechanism of action : They CONTRACT and then RELAX
SKELETAL MUSCLES (600) cause bones to move
Synergetic muscles : muscle groups that work together to create the same movement <=> Antagonistic muscles
Most are attached to bones via tendons, a few only to other muscles or toskin (eg muscles to smile)
ORIGIN (one end of skeletal muscle) joints to a bone that remains relatively stationary. INSERTION (other end)
attaches to another bone across a joint => If muscle contracts : INSERTION is pulled towards ORIGIN ! (origin is
closer to midline of body, insertion is further away)
A muscle is composed of MANY MUSCLE CELLS with same origin/insertion/function
Muscle cells : are arranged in bundles ‘FASICLES’, containing up to 1000s of muscle fibers/cells wrapped in several
layers of a FIBROUS connective tissue ‘FASCIA’ => At end of muscle, all fasciae come together & form tendons (which
attach muscles to bones) :
Long, tube shaped, Vary in length from few mm to 30 cm
>1 Nucleus, just under cell membrane.
The entire interior is packed w with ‘MYOFIBRILS’: long cylindrical structures in paralell, containing ‘contractile’
proteins ACTIN and MYOSIN. When myofribils contract => the muscle cells shortens.
Muscles produce movement or generate tension
Can generate heat (contraction of muscles accounts for ¾ of generated heat !)
40% M/ 32%F body weight = muscles
3 types : SKELETAL // CARDIAC // SMOOTH
Fundamental activity of muscle = CONTRACTION
1. Musles are Exitable : contract in reaction to chemical and/or electrical signals
2. One basic mechanism of action : They CONTRACT and then RELAX
SKELETAL MUSCLES (600) cause bones to move
Synergetic muscles : muscle groups that work together to create the same movement <=> Antagonistic muscles
Most are attached to bones via tendons, a few only to other muscles or toskin (eg muscles to smile)
ORIGIN (one end of skeletal muscle) joints to a bone that remains relatively stationary. INSERTION (other end)
attaches to another bone across a joint => If muscle contracts : INSERTION is pulled towards ORIGIN ! (origin is
closer to midline of body, insertion is further away)
A muscle is composed of MANY MUSCLE CELLS with same origin/insertion/function
Muscle cells : are arranged in bundles ‘FASICLES’, containing up to 1000s of muscle fibers/cells wrapped in several
layers of a FIBROUS connective tissue ‘FASCIA’ => At end of muscle, all fasciae come together & form tendons (which
attach muscles to bones) :
Long, tube shaped, Vary in length from few mm to 30 cm
>1 Nucleus, just under cell membrane.
The entire interior is packed w with ‘MYOFIBRILS’: long cylindrical structures in paralell, containing ‘contractile’
proteins ACTIN and MYOSIN. When myofribils contract => the muscle cells shortens.
