Transcript the thickness of fibers

 Skeleton means “dried up” in Greek--bones are actually made
up of:
 1/3 of water
 minerals
 blood and nerves
 You have more than 650 muscles in your body and 206 bones
 There are 3 types of muscles:
 Skeletal (move your bones)
 Cardiac (your heart)
 Smooth (located in the walls of blood vessels and organs)
Outer layer is the PERIOSTEUM
(peri = around)
(osteo = bone)
Strong layer is the COMPACT BONE
(have to cut with a saw)
(blood vessels and nerves run through this layer)
The inner layer is the SPONGY BONE
(looks like a sponge)
(where bone marrow is)
LIGAMENTS- connects bone to bone
TENDONS- connects muscle to bone
CARTILAGE- supports bones and protects them from
rubbing against each other.
Just a few listed here…there are many more
FIXED- don’t move
HINGE- moves bones through one plane (arm, leg)
BALL AND SOCKET- movement in several directions (hip
and shoulder)
There are 2 types of muscles filaments: MYOSIN (thick)
ACTIN (thin)
When a nerve signals a skeletal muscle to contract, calcium is
released inside the muscle filaments. This causes attachments
to form between myosin and actin.
The Sliding Filament Theory states that the actin filaments slide
toward one another during contraction. The myosin filaments do
not move. This shortens the muscle thus causing it to contract.
3 Relax
1
Attach
2
Slide
 Muscle strength does not depend on the number of fibers in
the muscles. This number is fixed before you are born.
 Muscle strength depends on the thickness of fibers and how
many of them contract at one time.
 Thicker fibers are stronger and contribute to muscle mass.
 Regular exercise stresses muscle fibers slightly, and to
compensate for this added workload, the fibers increase in size.