Transcript SKELETAL SYSTEM

SKELETAL SYSTEM
bones, ligaments, & tendons
Development of Bone
Joints -where bones meet!
IMMOVABLE joints
sutures in skull
SLIGHTLY MOVABLE
discs of vertebra
MOVABLE
 Ball-and-socket – shoulder, hip
 Hinge – elbow, knee
 Pivot- first two vertebra
 Saddle - base of thumb
 Gliding - carpals
 Ellipsoid - base of fingers
MUSCULAR SYSTEM
Muscles can only contract. They
pull on bones to make them
move
muscle types
o STRIATED ~ skeletal, voluntary
o SMOOTH ~ lines most internal
organs, involuntary
o CARDIAC ~ found only in
heart, involuntary
Muscle parts
o TENDONS attach the muscle
to the bone
MUSCLE CONTRACTION
“SLIDING FILAMENT THEORY”
 Thin filaments (ACTIN) and
thick filaments (MYOSIN) move
past each other by means of
CROSSBRIDGES (part of myosin),
thus shortening the myofibrils and
so shortening (i.e. contracting)
the muscle
ATP is required for muscle
contraction and is obtained by
either AEROBIC or ANAEROBIC
RESPIRATION
Nifty tidbits on the functioning of
muscle
 “All or none response” means
that a single muscle fiber either
contracts all the way or not at all
 Therefore the strength of a
contraction depends on how
many fibers fire at once
ATROPHY = disuse of limb
replaces muscle with fat and fibers
HYPERTROPHY = contraction to
75% max (and over time) causes
new myofibrils to be formed and,
hence, more muscle mass
SLOW-TWITCH FIBERS with steady
tug and more endurance (look
dark w/i the muscle)
FAST-TWITCH FIBERS more
anaerobic and seem to be for
strength and explosive bursts of
energy. They fatigue quickly (look
light w/i the muscle.)
Slow Twitch is for
endurance
marathon
Fast twitch is for speed and
strength
Exercises to help train fast-twitch fibers.