how do we move L12

exoskeleton

rigid outer covering that protects internal organs: artopods and shells

endoskeleton

rigid internal elements that offer sites for muscle attachment; protects internal organs and tissues ex: echinoderms and vertebras

hydrostatic

fluid filled cavity surronded by muscle ex. soft bodied terrestrial and aquatic invertebras

osteoblast

bone forming cells that secrete enzymes (the matrix) for bone formation

osteocytes

trapper in the matrix and differentiates into osteocytes which live in the lacuna and communicate with otner another in the canaliculi

endochondral

cartilaginous bones that develop into long bones: diaphysis and 2 epiphyses

-calcified bone replaces outer covering, osteoblast calcify interior cartilage

-growth plats: deposit new cells towards the shaft: length stops at puberty but width continues

intramembranous membrane

occures at connective layer- creates flat bones that leave suture lines

-precusor cells differentiate into osteoblasts which secrete enzymes that create crystals

cardiac

found in the walls of the heart; powers contraction (involuntary)

smooth muscle

found in the walls of blood vessels, stomach and intenstine; powers contraction from the CNS (involuntary)

skeletal

talking, lifting, walking (voluntary)

bone remodeling

force stimulates osteoblasts and causes to curve by widening

fast twitch fibers

fatigue more fast, less mitochondria, rapid power, sprinter

slow twitch fibers

fatigue more slowly, lots more mitochondria, endurance, marthoner

cross bridge 1

the energized mysosin head bonds with actin to form a cross bridge

cross bridge 2

mysosin returns to its normal state by releasing ADP + P which pulls the mysosin head in one direction

cross bridge 3

the cross bridge breaks bc ATP binds to the myosin head

cross bridge 4

ATP is hydrolyzed, which returns the myosin head to its energized state

nucleomuscular junction

nerve impulse releases acetylcholine. Na+ rushes into the cell and depolarizes causes Ca2+ to flood cells and reveals binding sites

when there is no Ca2+

when muscles are relaxed state, the energerized myosin heads do not form cross bridges with actin bc the attachment site is blocked by tropomyosin

when there is ca in the environment

when a muscle contracts, increase of Ca2+ that binds to toponin to cause a conformation change in the complex —> cross bridges form