Skeletal + Muscle System

hydrostatic skeleton

A fluid skeleton in many soft-bodied invertebrates, including annelids, that allows an organism to change shape but not volume.

Hox-genes

variations of skeletal arrangement in vertebrates due to master control (homeotic) genes

Periosteum

a dense layer of vascular connective tissue enveloping the bones except at the surfaces of the joints that acts as an interface between bone, blood vessels, and the ligaments/tendons

trabecular

branching plates of bone; forming irregular cavities

lamellae

Layers of bone matrix

myocytes

tubular cells that comprise muscles

Myofibrils

elongated contractile threads found in striated muscle cells.

filaments

found in muscle fibers composed primarily of the proteins myosin and actin

sarcomeres

units composed of actin and myosin that contract inside the muscle fiber

isotonic contraction

muscle shortens because muscle tension exceeds load

cocentric contraction

tension is greater then the load, and fiber shorten;

shortening of muscle

eccentric contraction

muscle lengthens when load is more than peak tension

isometric contraction

no shortening; muscle tension increases but does not exceed load

locomotion

Active travel from place to place

Exoskeletons

thick, hard outer coverings that protect and support animals' bodies

Endoskeletons

consist of hard or leathery supporting elements
situated among the soft tissues of an animal.

axial skeleton

Portion of the skeletal system that consists of the skull, rib cage, and vertebral column

appendicular skeleton

The portion of the skeleton that attaches to the axial skeleton and has the limbs attached to it

flat bones

These bones are thin, flat, and often curved. They form the ribs, breastbone, and skull.

long bones

cylindrical in shape, function as levers; move when muscles contract

sesamoid bones

Small, rounded bones that protect tendons

irregular bones

complex shaped bones like vertebrae

fibrous connective tissue

covers most of the outer surface of bone; forms new bone in the event of a fracture

cartilage model

the hyaline cartilage that takes the shape of the future bone during endochondral ossification

mature bone cells ___________

cannot divide because they are enclosed in a solid matrix

endochondral ossification

Process of transforming cartilage into bone

spongy (cancellous) bone

mesh-like bone tissue containing marrow and fine branching canals through which blood vessels run

ligament

bond of strong fibrous connective tissue that holds together the bones of movable joint

Osteocytes

mature bone cells

Osteoblasts

Bone building cells (B- build)

osteoclasts

Bone-destroying cells (C- kill)

functions of bone

- protection
- mineral + growth factor storage
- blood cell formation

axial muscles

support and position axial skeleton

appendicular muscles

support, move, and brace limbs

tendons

Connect muscle to bone

antagonistic muscles

opposing sets of muscles that are required to move a muscle back and forth

myosin

thick filament

actin

thin filaments

sliding-filament model of contraction

the sarcomere contracts when thin filaments slide along thick filaments- powered by ATP

motor neuron

a neuron that sends an impulse to a muscle or gland, causing the muscle or gland to react

sarcoplasmic reticulum

specialized endoplasmic reticulum of muscle cells

slow twitch fibers

red muscle fibers that are slow to contract but have the ability to continue contracting for long periods of time; full of myoglobin

fast twitch fibers

white muscle fibers that contract rapidly and forcefully but fatigue quickly; cycle myosin faster- ATP from fermentation