Musculoskeletal System

• Why is locomotion essential to most organisms?

• Motile vs. Sessile

– Get food– Move away from harmful things and predators– Seek shelter– Seek out mates

Skeletons

• Humans and other vertebrates have endoskeletons– Made of bone and

cartilage– Can grow along with

animal

• Insects and animals like crabs and lobsters have exoskeletons– Made of chitin– Jointed and flexible– Muscles attached from inside– Must be shed periodically for organism to grow larger

Bone• Hard inflexible tissue

• Made of living bone cells called osteocytes

• Haversian Canals– inner cavities containing blood vessels and nerves

Broken Bones

– If bone is broken, osteocytes become active and produce new bone

Bone

• Function:– Site of attachment of skeletal

muscles– Levers that make body parts move

when muscles contract– Protect delicate structures like

brain and spinal cord– Storage site for important minerals

like calcium– Place where red blood cells and

some white blood cells produced

• Types of Bones:– Compact bone– Spongy bone

• Marrow: – Tissue found in long bones

– make RBC, platelets, some types of WBC

Joints

• Point where bones meet

• Immovable– Bones tightly fitted together

• Ex: skull

• Movable– Hinge Joint

• Ex: elbow and knee

– Pivot Joint• Ex: base of skull

– Ball and Socket Joint• Ex: Hip, shoulder

– Saddle Joint• Allow Ex: wrists

Types of Joints

Cartilage

• Found between joints

• Found in nose and earlobe

Cartilage

• Provides support and flexibility

• Allows bones to bend more easily

• Cushions bones against impact or pressure

• Makes up most of an embryo’s skeleton

Ligaments

• Tough elastic fibers

• Hold bone to bone at the joints

• http://www.youtube.com/watch?v=VsBJ4oUff10&safe=active

Types of Muscles

http://www.youtube.com/watch?v=YyfytTqbgUE&safe=active

Types of Muscles

• Skeletal Muscle (striated)– Voluntary movement,

locomotion – Bundles of muscle fibers– Appear striped or “straited”

under microscope

• Human locomotion is made possible by voluntary contractions of striated muscle.

• Muscles operate in pairs:– Flexors: bend limb– Extensors: extend limb

• Muscle Contraction– Muscle fibers contain contractile proteins– Require ATP (many mitochondria in muscle)

Types of Muscles

• Smooth Muscle (nonstriated)– Involuntary– Controlled by autonomic

nervous system– Found in:

• walls of digestive organs blood vessels, bladder

Types of Muscles

• Cardiac Muscle– Found in heart– Involuntary– Cells contract

together as a unit

Tendons

• Inelastic connective tissue

• Attaches muscle to bone

Disorders of Muscular/Skeletal System

• Tendonitis– Inflammation of connective tissue called

tendons that connect muscles to joints

• Arthritis– Inflammation of the

joints– Deterioration of cartilage

• Osteoporosis: – loss of bone due to calcium deficiencies

Locomotion in Animals• Protists

– Pseudopods (amoeba)– Cilia (paramecium) and flagella (euglena)

• Hydra– Tends to be sessile but can glide along base,

do somersault or use tentacles to pull itself

• Earthworm– Uses muscles to burrow into soil– Has tiny bristles on each segment (setae) that

hook onto earth to help it move

http://www.youtube.com/watch?v=bFpblBf1dfE&safe=activehttp://www.youtube.com/watch?v=0Texxu3p7I8&safe=active

• Grasshopper– Exoskeleton made of chitin divided into

plates that have flexible joints– Muscles attached from the inside– Can walk jump, fly (3 pairs of legs and wings)