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| found primarily in soft-bodied terrestrial invertebrates (earthworms & slugs) |
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Term
| Musculoskeletal action in earthworms |
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Definition
circular muscles (repeated segments); longitudinal muscles (oppose action of circular muscles); these muscles act on fluid in body's central space
anterior muscles contract pressing on inner fluid, forcing front of body to become thin as body wall in this region extends forward |
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Definition
short, bristle-like structures on underside of worm's body that act as anchors; when circular muscles act, chaetae of that region are pulled close to body & lose contact w/ ground; circular-muscle activity is passed backward to create a wave of contraction;
as wave continues, longitudinal muscles thicken front end of worm alowing chaetae to protrude & regain contact with the ground |
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Term
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Definition
| ejection of fluid taken in from environment; used for locomotion; not forceful-keeps organisms like jellyfish afloat; strong-squid (water is expelled forcefully through siphon & animal shoots backward); typically method of making a rapid esape |
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Definition
| jellylike mass of jellyfish; + contractile fibers around edge of bell->contractions of the fibers produce pulsations that squeeze the bell->water is forced out of the bell; mesoglea resets the bell |
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Definition
| surround the body as a rigid hard case |
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Definition
| makes up exoskeletons of arthropods, such as crustaceans and insects; also found in cell walls of fungi & some protists |
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Definition
| method of growing for organisms with exoskeletons |
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Definition
| found in deuterostomes; rigid internal skeletons that form body's framework & offer surfaces for muscle attachment |
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Definition
| rigid special connective tissue; strong & slightly flexible; pads end of bones where they come together in a joint; living tissue |
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| main component in vertebrate skeletons; much stronger than cartilage but less flexible; living tissue; first appeared in eel-like creatures, conodonts |
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Definition
| bones of this skeleton form axis of body beginning with skull in front & ending with tail behind |
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Term
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Definition
| set of limb bones (or fish bones); & associated pectoral girdle/pelvic girdle (fore/hindlimbs); fish: pectoral girdle connected to skull; terrestrial vertebrates: pg's tied to ribs through fibrous connective tissue & muscle + one or more sacral vertebrae |
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Term
| intramembranous development (simple method of bone development) |
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Definition
| bones form within a layer of connective tissue (i.e. skull); begins in a designated region in the dermis; during embryonic development dermis is formed of mesenchyme (undifferentiated mesenchyme cells, other cells, & collagen fibers); some mesenchyme cells differentiate to become specialized->osteoblasts |
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Definition
| specialized cells; arrange themselves along collagenous fibers & begin to secrete enzyme alkaline phosphatase (causes Calcium Phosphate salts to form hydroxyapatite); crystals (give bone its hardness; resilience afforded by collagen keeps bone from being brittle) merge along fibers to encase them; |
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Definition
| formed by calcium phosphate salts when enzyme alkaline phosphatase is secreted by osteoblasts |
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Definition
| osteoblasts trapped in bone matrix that undergo changes in shape & function (encased in lacunae); |
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Definition
| canals extending from lacunae; permit contact of extensions of each osteocyte with its neighbors |
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Definition
| formed from fusion of monocytes (type of white blood cell); to form large multinucleate cells whose function is to break down bone matrix as intermembranous bone grows |
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Term
| Endochronal development (complex bone development) |
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Definition
bones that develop this way are typically those deeper in the body that form the architectural framework (i.e. vertebrae, ribs, bones of the shoulder/pelvis, limbs); begin as cartilaginous models->bone is added to the outside while replacing interior cartilage with bone;
fibrous sheath (collagen fibers + mesenchyme cells) that envelops cartilage produces bone that's added over cartilage; osteoblasts sort themselves along fibers in deepest part of sheath & bone is formed between the sheath & the cartilaginous matrix |
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