muscular System

Function of muscles

movement or body parts and organs
stability - maintain posture and prevent movement
communication- speech, expression, and writing
control of openings and passagways
heat production

Fasicles

large bundles of muscle fibers
multiple fasicles form a muscle

Endomycia

layer of connective tisue around each cell (thin aerolar) allows room for cappilaries and nerve fibers.

perimycium

connective tissue around fasicles

Epimycium

covers whole muscle

fascia

belly blends into CT between muscle

Skeletal Muscle Belly

thicker middle region of muscle
Belly gets fatter, as a muscle gets shorter

Skeletal Muscle Origin

attachemtn to stationary end of muscle( bone thats not moving)

Skeletal Muscle Origin

attachemtn to stationary end of muscle( bone thats not moving)

Insertion

attachment to mobile end of muscle( bone that is moving)

Skeletal muscle Shapes
Fusiform

Thick in middle and tapers at end
biceps in brachii

Skeletal muscle Shapes
paralell muscles

have paralell fasicles
rectus abdominus

Skeletal muscle Shapes
Convergent muscle

broad ar origin and tapering to a narrower intersection
Converge- come together

Skeletal muscle Shapes
Pennate muscle

Feather Shaped
fasicles insert obliqely on a tendon
unipenate, bipenate, multipenate
palmar interosseous, rectus femoalis, and deltoid

Skeletal muscle Shapes
circular muscles

ring around body opening
orbicularis oculi

Prime mover/ agonis

produces most of the force

Synergist

aids the prime mover
stabalizes nearby joints
modifies the direction of movement

Antagonist

opposes the prime mover.
prevents excessive movement and injury

fixator

prevents movement of a bone

Intrinsic muscle

located in the same place the movement is happening

extrinsix muscle

located away from the movement area

characteristic of muscles

muscle cells convert chemical energy(ATP) into mechanical energy of movement

Responsiveness/ excitability

two chemical signals, stretch and eletrical changes across the plasma membrane

conductivity

local electrical change triggers a wave of excitation that travels along the muscle fiber

contractability

shortens when stimulated
muscles the only tissue that shortens when stimulated

extensibility

capanle of stretching

elasticity

returns to its iriginal reting length after being stretched

generalized skeletal Muscle

voluntary striated muscle attached to bones
as long as 30 cm
light and dark striations(reflects overlapping of intrcontractile proteins)
under consious control

muscle cells

multiple flattened muclei inside cell membrane

sarcolema

plasma membrane of muscle cell

Transverse(T) Tubules

Run through the cell and through the other end
carries electrical currents to cell interior