Types of Muscle, structure and

Function

Types of muscle

►3 General types►1) Smooth (visceral)

muscle► Loosely associated

fibers►Peristalsis► Found in dig. tract,

lungs, arteries

Cardiac Muscle

►Tightly associated fibers

►Gap junction and intercalated discs allow for quick exchange between cells

► Found only in the heart

Skeletal Muscle

►Tightly associated fibers

►Responsible for moving the skeleton

► Found everywhere in the body attached to skeleton

Structure of Skeletal Muscles

►Long thin fibers of sarcomeres connected end-to-end

►Fibers bundled into fascicles

Sarcomere

Sarcomere

►Basic unit of contraction►Sarcolemma surrounds it►Actin – thin filament

►Mysosin- thick filament

►Tropomyosin covers myosin clubs to prevent bonding during relaxation

How contraction occurs

►Brain triggers muscle to contract

►Message travels down nerve

►Crosses synapse and hits sarcolemma

Next….

►Sarcolemma releases Calcium ions into sarcomere

►Ca binds with troponin

►Triggers tropomyosin to move

Contraction begins

►With tropomyosin out of the way, myosin clubs attach to actin filament

► Forms cross bridges

Finally…

►ATP binds to cross bridge

►Causes club position to move

►Pulls actin fiber with it

►Shortened sarcomere = contraction

After contraction

►ATP is required to break bonds and relax muscle

►Rigor mortis