Skeletal and Muscular Systems Movement and Support in Animals Biology 137

There Are Two Types of Skeletal Systems Exoskeletons Endoskeletons

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 Clavicle Humerus Maxilla Mandible Radius Ulna Carpals 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 Bone Tissue Type Function 1. LigamentsConnect one bone to another 2. PeriosteumSupplies blood to the bone 3. Compact boneVery strong – Stores Calcium 4. Spongy boneLight but very strong 5. MarrowMakes blood cells 6. CartilageCushions 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 HOME How 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