Muscles of the human body:
Muscle characteristics: 605 in the human body Maintains posture Generate heat Stabilizes joints Locomotion Facial expressions Manipulation of the environment
Three muscle types: Smooth-uninucleated,involuntary and nonstriated; walls of the blood vessels and hollow visceral organs (stomach and bladder) Cardiac-uninucleated, involuntary and striated; walls of the heart Skeletal-multinucleated, voluntary and striated; muscles of the body
Terms: Myo-muscle Tendon-connects muscle to bone Ligament-connects bone to bone Myotendonous junction-junction where muscle and tendon meets Muscle attachment-origin-less movable bone; insertion-movable bone Muscle cells are called muscle fibers
Why are muscle cells so strong? There are many muscle fibers bundled together with connective tissue in muscles
Muscle structure: Muscle fiber (cell)-connective tissue of endomysium-group of muscle fibers covered by perimysium(fascicle)-groups of fascicles covered by epimysium
Types of muscle fibers: Slow twitch-fatigue resistant-contract for a long time-endurance Fast twitch-fatigue-cannot contract for a very long time-speed
Microscopic muscle structures: Sarcolemma-plasma membrane in muscle cells Myofibrils-long organelle composed of myofilaments Sarcomeres-tiny contractile units found in myofibrils
Myofilaments: Small protein structures in a banding pattern Myosin (protein)-thick filament-extend entire length of the A band-forms the cross bridges (golf heads) Actin (protein)-thin filament
Muscle contraction: Muscle sliding filament theory Calcium is the go signal for contraction ATP needed for contraction and relaxation
Building muscle: Destroy and break down the muscle fibers-replaced with bigger and better fibers-muscle adapts to stress