MUSCULAR & SKELETAL SYSTEMS Honors Biology

SKELETAL SYSTEM Adults have 206 bones in their Endoskeleton Skeleton – Appendicular: arms, legs, scapula, clavicle, pelvis – Axial Skeleton: skull, ribs, spine, sternum Function – Framework for muscles to pull on – Shape and structure to body – Protect internal organs – Store minerals – Make red and some white blood cells

BONE STRUCTURE Moist living tissues Surrounded by PERIOSTEUM Hard material; COMPACT BONE – Cylinders with blood vessels – Osteocytes: living bone cells SPONGY BONE BONE MARROW: – Red makes RBC and some WBC – Yellow stores fat

BONE DEVELOPMENT Most develop from cartilage Ossification: making bones with minerals Bone elongation at epiphyseal plate

JOINTS – WHERE BONES MEET Fixed joints prevent movement: skull Semimovable joins: limited movement (vertebrae, rib cage) Movable joints: most joints – Hinge: elbow – Ball and socket: shoulder – Pivot: top of spine (turn head side to side) – Saddle: base of thumb; rotate thumb – Gliding: slide over each other; bones in foot

JOINT STRUCTURE Lots of pressure and stress Covered with cartilage Ligaments hold bones in place Lubricated with synolvial fluid Arthritis: bones rub together when cartilage wears down

NAMES OF BONE REVIEW WORKSHEET PLAY GAMES BE READY FOR QUIZ

MUSCULAR SYSTEM Muscles can contract which allows body to move and push substances through the body Muscle is a tissue that can contract Muscle Types – Skeletal Muscle: moves bone, made of muscle fibers; striated; voluntary – Smooth Muscle: involuntary; lines organs, spindle shaped; not striated – Cardiac Muscle: heart; involuntary but striated

MUSCULE STRUCTURE Each muscle fiber is a single multinucleated muscle cell Muscle made of 100s or 1000s of fibers Each fiber is made of myofibrils Each myofibril is made of thick and thin protein filaments

MUSCLE STRUCTURE Thick filaments are myosin and thin filaments are actin; overlapping patterns Thin actin anchored to Z line Sarcomere is between Z lines

MUSCLE CONTRACTION Sarcomere is functional unit Contract: – Myosin and actin shorten length – Heads of myosin attach to points between actin filaments – Myosin bends in and pulls actin with them – Myosin lets go, attaches to new area and pulls again – Shorten muscle fiber Needs Energy All or Nothing

MUSCULAR MOVEMENT OF BONE Skeletal Muscles attach to one end of a bone, stretch across and attach to other end Origin is where it attaches to stationary bone; insertion is where it attaches to moving bone ARRANGED IN PAIRS – Move bone by pulling them – Flexor (bicep) bends bone in one direction – Extensor (tricep) straightens bone in other direction