Transcript Chapter 39 - Musculoskeletal System

Musculo-Skeletal System
Muscles + Bones = Locomotion
Quiz this Week!
Thursday
Chapters #35 and #37
http://www.vcld.org/pages/newsletters/01_02_fall/testtaking.htm
Muscles
Why muscles?
• Muscle tissue is responsible for
movement and locomotion in animals.
• Muscles rely on contractile fibers to
create motion.
• In vertebrate animals and arthropods,
muscles attach to a skeletal system to
produce locomotion.
Types of muscle tissue
•These three types are
found in vertebrates:
•Skeletal: striated,
voluntary control
•Smooth: involuntary
control
•Cardiac: involuntary
control
Smooth muscle
• Found in the
digestive tract, large
blood vessels, and
several organs.
• Have contractile
fibers, but lack
orderly striations of
skeletal muscle.
Cardiac muscle
• Located only in the
heart.
• Influenced by
nerves and
hormones, but has
“electrical” system
of its own to initiate
and coordinate
contractions.
Skeletal muscle
• Muscle tissue
capable of voluntary
control.
• Orderly striations
are due to
arrangement of
contractile fibers.
• Produces
locomotion.
Muscle fibers
• A muscle cell is a
“fiber.”
• Fibers are
multinucleated and
contain myoglobin.
• Myofibrils contain
the contractile
fibers.
Slow Twitch, Fast Twitch
• Slow-twitch fibers: lots of myoglobin,
mitochondria. Good for endurance activities.
• Fast-twitch: less myoglobin, but more able to
use glycolysis to quickly produce ATP. Good
for activities required sudden strength or
speed.
• Different people have different ratios of these
two fibers.
Myofibril
• The myofibril is
composed of “thick”
and “thin” filaments.
• Each of these
filaments is made
up of strands of
protein.
Thick and thin filaments
• The thick filaments,
made mostly of
myosin, have small
“heads” that move.
Thick and thin filaments
• The thin filaments
have points to
which the myosin
heads temporarily
attach.
Muscle fiber action
Muscle fiber action
Muscle fiber action
All or nothing
• Fibers are either “on”
(contracted) or “off”
(relaxed).
• When lifting light
weights, only a few
fibers may be “on.”
For heavy weights,
many more may be
“on,” and may take
turns to prevent
fatigue.
Working out
• Exercise can build
muscle mass. However,
because muscle fibers
(cells) are large, they
rarely divide.
• To increase muscle
power, muscles add
more filaments inside of
the fibers. This
happens when muscles
rest after exercise.
Stretching
• Stretching exercises add
flexibility by increasing
muscle length.
• On the molecular level, the
filaments within the
muscle can increase in
length to accommodate
stretching.
• However, stretching
tendons can weaken
joints.
Try this:
• Hold your pen or pencil so that it casts a
shadow on your paper. Line up the tip of
the shadow with a point on your paper.
• How still can you hold your hand? Does
the point of the shadow move? Muscles
generally contract by continuous
“twitching” of muscle fibers. This makes
it hard to hold your hand completely
steady.
Skeletal Systems
Types of systems
• Three basic types of skeletal
systems in the animal kingdom:
• Hydrostatic
• Exoskeleton
• Endoskeleton
Hydrostatic skeleton
• Earthworms and sea
anemones have a
hydrostatic skeleton.
• Circular muscles
squeeze the body,
forcing water to both
ends, which lengthens
the body. Longitudinal
muscles shorten the
body, making it wider.
Exoskeleton
• Arthropods (insects,
spiders, etc) have
an external skeleton
made of chitin (a
carbohydrate).
• Muscles attach to
the exoskeleton,
which is flexible at
the joints.
Endoskeleton
• Vertebrates have an
endoskeleton made
of cartilage or bone.
• Bone and cartilage
are living tissue
(connective tissue),
allowing the
skeleton to grow
with the organism.
Functions of the endoskeleton
• Support and protection for the body.
• Locomotion (in concert with muscles).
• Produce blood cells in bone marrow.
• Store calcium and phosphorous.
• Store energy in yellow marrow.
Cartilage
• Cartilage tissue
consists of
chondrocytes
(cartilage cells) in a
matrix of collagen
protein.
• Cartilage is tough,
flexible material that
pads joints and is
found in the nose and
ears.
Bone tissue
• Bone is made up of
bone cells in a
matrix of collagen
and minerals.
• Three types of bone
cells: osteocytes,
osteoblasts, and
osteoclasts.
Bones
• Bones may made up
of:
• Compact bone tissue.
• Spongy bone (location
of red marrow)
• Marrow cavity
(location of yellow
marrow)
Healing fractures
Osteoporosis
• Osteoporosis is loss
of bone mass, leading
to brittle bones.
• Age, lack of calcium,
sedentary lifestyle,
multiple pregnancies,
menopause, alcohol,
and smoking
contribute to
osteoporosis.
Locomotion
Motion in Vertebrates
• Motion and locomotion are produced by muscles
pulling on bones.
• Joints in the skeleton allow for parts of the body
to flex and extend, allowing for motion.
Ligaments attach bones to bones at the joints.
• Muscles attach to bones by tendons.
Hinge joint
• A hinge joint allows
flexing and
extending along
one plane.
• Pairs of muscles
work opposite one
another to create
motion.
Ball and socket joint
• A ball and socket
arrangement allows
rotational
movement.
• Multiple pairs of
muscles allow
movement in a
range of directions.
Gliding joints
• In gliding joints,
bones slide past
one another.
• Gliding joints allow
twisting motion.
On your own paper...
• The knee is a hinge joint. Find another
hinge joint in the body. What muscles move
it?
• The hip is a ball and socket joint. Find
another ball and socket joint in the body.
What muscles move it?
• The wrist is a gliding joint. Find another
gliding joint in the body. What muscles move
it?
Movement
• Flexion: decreases angle of a joint.
• Extension: increases angle of a joint.
• Abduction: movement away from
midline.
• Adduction: movement toward midline.
• Rotation: turning around an axis.
On your own paper...
• Give examples of joints and movements
that demonstrate:
• Flexion
• Extension
• Abduction
• Adduction
• Rotation
Name that muscle!
• For each of the following slides:
• Name the muscle or muscle group, if you
can.
• State what kind of movement it produces.
• Locate the bone (or bones) that it moves.
• Which muscles produce the opposite
movement?