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Skeletal and Muscular Systems
Movement and Support in Animals
Biology 137
There Are Two Types of Skeletal Systems
ExoskeletonsEndoskeletons
Functions of the Skeleton
1. Supports the body
2. Protects the soft body organs
3. Makes blood cells and platelets
4. Stores calcium and other minerals
5. Helps with movement
How can bones help your immune system?
• Bone marrow has many useful cells!– Red marrow produces red blood cells
which carry oxygen throughout the body.– Red marrow also produces white blood
cells to fight disease!– Yellow marrow helps store fats and
produces red blood cells during major injury.
Do you know the bones of the skeleton?
Cranium
ClavicleHumerus
Maxilla
Mandible
Radius
UlnaCarpals
Metacarpals
Phalanges
Femur
Patella
Tibia
Fibula
Sternum
Scapula
Pelvis
Tarsals
Metatarsals
Phalanges
Sacrum
Vertebrae
Ribs
Bone Growth
Baby Adult
Who has more bones – an adult or child?
Formation of Bone• When you are developing as a baby, your
bone starts as cartilage.• Blood vessels stimulate cartilage and turn it
into potential bone cell (Ossification)• Cells secrete hormones that make the bone
harden.• Osteoblasts build bone & store calcium.• Osteoclasts break down bone & release
calcium.
Bone Structure
Growth Plate
(Contains Red Marrow)
(Also called compact bone)
(Periosteum)
(Contains yellow marrow)
6 Tissues Make up BoneTissue Type Function
1. Ligaments Connect one bone to
another
2. Periosteum Supplies blood to the bone
3. Compact bone Very strong – Stores Calcium
4. Spongy bone Light but very strong
5. Marrow Makes blood cells
6. Cartilage Cushions bones at joints
Joints – Where Bones Meet
Gliding joint.
Slight movement.
There are 4 Main Types of Joints
Hinge Joint:
One direction only.
Ball & Socket Joint:
Greatest range of motion.
Fixed Joint:
No movement
The Muscular System
It will “pump you up!”
Lou Ferrigno – The Hulk
Where do we find muscle?• EVERYWHERE!
– Muscles are located everywhere on the body!• Ex: Arms, legs, back, stomach, face,
hands, feet, etc.
There Are Three Types of Muscle Tissue
Muscle Type: Skeletal• SKELETAL (striated or striped)
– cells are long, cylindrical, and rarely branched– Many nuclei along edges of cells– Attached to bones by tendons
• Only operate when you want them to-- VOLUNTARY• Controlled by the nervous system.• Necessary for movement of the skeletal system.
Muscle Type: Smooth• SMOOTH (involuntary)
– No striated (striped) pattern– Cells contract slower, but longer– Found in walls of blood vessels, digestive tract
(intestine, stomach), urinary bladder and in the iris• Work automatically without thinking about it. Works
even while you sleep.• Controlled by the nervous system.• Small, spindle shaped cells.
Muscle Type: Cardiac• CARDIAC
– Found only in the heart– Striated (striped) like skeletal muscle– One nucleus with branched ends– Will continue to contract if nerves to heart are cut
• Only found in the heart.• Never gets tired.• Cells connected like a tightly
woven bag.
Muscles and Contraction
Every movement is done in pairs! One muscle contracts, while the
other relaxes.– Ex: As you move your hand up to your
shoulder, you tighten your bicep and it contracts. The muscle on the other side of your arm, the tricep, relaxes.
– The opposite happens when you return your hand to your waist, the tricep contracts and the bicep relaxes.
Muscles Work In Pairs
One muscle bends (flexes) a joint, and an opposing muscle is needed to straighten (extend) it.
How Do Muscles Work?
A muscle can only pull. It does this by becoming shorter. When it contracts, the joint bends.
Endoskeleton vs. Exoskeleton
Muscle Filament Structure
Sliding-Filament Model
Acetylcholine (ACh) depolarizes the plasma membrane of the muscle fiber
Neuromuscular junction
Opposing Muscles Move Us
TRY THIS AT HOMEHow does fatigue or rest affect
muscle performance?• Volunteer #1 – Do twenty pushups• Volunteer #2 – Rest in your chair• Lift two books over your heads.• Which one has the most trouble?
Do you think muscles ever change their performance based on rest or tiredness?
What are some examples of this?
Skeletal System Problems
Fractured bones (cracks and breaks).
Sprains: stretched or torn ligaments (bone-to-bone).
Strains: stretched or torn tendons (muscle-to-bone).
Diseases: Arthritis, osteoporosis, cancer, leukemia.
Why do your muscles get tired?
• Why can’t your nerves just tell the muscles to contract more?– When muscles are working they are using
energy and producing lactic acid (remember lactic acid fermentation???)
– Eventually, the muscles get fatigued and this affects performance.
– You get cramps when there is a lack of oxygen and the lactic acid builds up.
Fractures
Worn out joints may sometimes be replaced with artificial ones.
Sometimes Knees Wear Out Too
Daily Herald, Monday, March 29, 2004
Implants Replace Worn or Damaged Joint Surfaces In The Knee
The End