Skeletal Muscle or Voluntary Striated Muscle
under control of conscious mind
looks striped under microscope
light and dark bands
ind. muscle cell, aka muscle fibers, are the largest cells in human body.
muscle fiber runs entire length of muscle
each muscle fiber contains myofibrils: contractile subunits
each cylindrical myofibril is surrounded by
Sarcoplasmic reticulum: rich in Calcium ions, network of tubes
T-tubules-deep indentations in muscle fiber are tubules
SR and Tubules critical for muscle contraction
each myrofibral contains subunits called sarcomer.
sarcomeres end at the junction of the Z-line
on this Z-line contains the two protiens, Myocin and Acetine
these two protiens enable contraction of muscle.
Slide 3
Muscle Attachments
Most muscles attach to bone at both ends through a fibrous connective tissue:tendons
Aponeuroses: a sheetlike tendinous expansion that fastens muscles to the parts it moves, proximal or distal attachment of a flat muscle.
Muscles have a couple attachments sites in order to move over bone and other muscle. 1. Origin of the muscle is more stable: it doesn't move when muscle contracts.2. insertion of the muscle: less stable, more movement.
Prime Mover:muscle group that directly produces the movementAntagonist: opposes the prime moverSynergist: a muscle that contracts at the same time as the prime mover; Fixator Muscles, for example, stabilize joints to allow other movements to take place.
Action: a muscle's name according to function. Flexor muscles flex.Shape: deltoid muscle, means triangular muscle of the shoulder region.Location: muscle's name denotes locality; biceps brachii means upper arm region.# of heads or divisions: triceps muscle has three attachment sites. bi-two...
real long
skeletal muscle cells look like fibers, hence, skeletal muscle fibers
poly-nuclei
sarcolemma- muscle cell membrane
biggest vol. of skeletal muscle fiber is made up of small microfibrils.
organelles between MF have energy producing mitochondria, network called sarcoplasmic reticulum.
Rubrica: : The diagram below describe the arrangements of actin and myosin. Please note that actin filaments are made of chains of globular actin molecules
structure of skeletal muscle: composed of bundles of fibers, myofibril made of smaller myofibrilsmyosin: thick filamentsactin: thin filaments
Slide 10
Neuromuscular Part
Neuromuscular junctions are nerve fibers that connect to muscle fibers. Motor Unit: a nerve fiber that innervates all the other fibers. sets the chain reaction. -mscl/MU: small muscles that make tiny, delicate moves(like the eye) require less muscle fibers per Motor Unit. arms, legs, more motor units
Connective Tissue LayersHold the Fibers together: Each muscle fiber is surrounded by outer tissue filled with fine reticular fibers called EndomysiumPerimysium bounds the fascicles,musc ske fibers, even tighterEpimysium: the fascicles are surrounded by Epimysium.
Slide 12
Physiology of Skeletal Muscle
Nerve impulse----motor nerve fiber--- reaches end bulb~neuromuscular junction releases Acetylcholine into synaptic space.-the contraction process of the muscle is powered by ATP( adenosine triphosphate), gives energy. contraction and relaxation requires energyCA in fiber yields CA in bloodstream
-the basics of muscle contraction is broken down into 3 phases. -latent phase-hesitation btw nerve stim and contrct: last 0.01contracting phase 0.04 secondsrelaxation phase. 0.05 seconds
-Muscle gets energy from ATP-ATP are like batteries: release energy and then need recharging-3 phosphate groups attached to adenosine core.-phosphate group released: considerable amt of energy: forms adp.Creatine Phosphate is the battery charger that converts ADP back to ATP.
Intercalated discs are microscopic identifying features of cardiac muscle. These discs fasten the cells together and it transmits impulses from one cell to another. -requires no external stimulation-self-efficient-Sinoatrial Mode is a natural pacemaker.
nerves to heart come from autonomic portion of the NS.
Sympathetic fibers: beat harder and faster.
Parasympathetic fibers slow down heart.
Slide 20
Smooth Muscle
AKA nonstriated muscle or involuntary muscle.
found all over the body
it comes as, Visceral Smooth Muscle, large sheets of cells in the walls of hollow organs.
multiunit smooth muscle: or as small, discrete groups of cells.
Visceral Smooth Muscle-As with any muscle, the smooth, involuntary muscles of the visceral muscle tissue (which lines the blood vessels, stomach, digestive tract, and other internal organs) are composed of bundles of specialized cells capable of contraction and relaxation to create movement