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

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Types of Muscles

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

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)