support, movement, protection, production, and storage
5 functions of the bones joints and muscles
cortical bone
dense bone that forms the outer shell
trabecular bone
sponge bone found at the ends of long bones and in vertebrae
ostepblasts
build new bone
osteoclasts
break down bone tissue
osteocytes
mature bone cells that maintain the bone matrix
bone remodeling
helps repair micro-damage and adapt to new loads in response to stress and hormonal signals bone reforms
PTH calcitonin and vitamin D
hormones that play key roles in regulating calcium levels and bone turnover
osteoporosis
balance between bone resorption and formation is disrupted leading to fragile bones
synarthrosis
non-synovial immovable joint (growth plate, between distal ends of radius and ulna, root to tooth to mandible)
amphiarthrosis
non-synovial slightly movable joint (vertebrae, symphysis pubis)
diarthrosis
freely movable joint (shoulder, elbow)
synovial
cavity filled with lubricant freely movable
uniaxial joints
includes hinge and pivot joints
hinge
joint- angular movement in 1 axis and 1 plane (elbow finger knee)
pivot
joint- rotary movement, a ring rotates around (radioulnar, 1st and 2nd cervical vertebrae)
biaxial joints
includes saddle and condyloid joints
saddle
articulating surface of 1 bone is convex and surface of 2nd bone is concave (thumb)
condyloid
angular motion on 2 planes without axial rotation (wrist between distal radius and carpels)
multiaxial joints
includes ball and socket and gliding joints
ball and socket joint
joint- round end of bone into cuplike cavity (shoulder hip)
gliding joint
joint- sliding motion (vertebrae, tarsal bones of ankle)
tendons
strong connective tissue, outer cover of muscle belly, attaches muscle to bone
cartilage
avascular, dense, connective tissue covers end of opposing bones withstands increased pressure and tension
ligaments
strong fibrous connective tissue, connect bones to each other at joint level and encase capsule, support purposeful joint movement and prevent wrong movement
bursa
enclosed sac filled with viscous fluid located in areas of potential friction act as cushion between surfaces
myofibrils
make up the skeletal muscle fibers
sarcomeres
repeating units of myofibrils that are the functional units of contraction
sliding filament theory
explains how muscles contract
myosin heads bind to actin filaments and pull them inward shortening the sarcomere
muscle contraction
ATP
required for muscle contraction; triggered by calcium ion release
calcium ions
released from the sarcoplasmic reticulum
excitation contraction coupling
begins with a nerve impulse travels down the motor neuron and results in muscle contraction