Bernal, Griffith Joyner D._BSBio1-4_Skeletal System_Notes.pdf

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Skeletal System of VertebratesSkeletal System2 types of skeletonCartilageBonesmost important organ systemcomposed of mineralized connective tissues-dentin, enamel, cartilage, and bones-skeleton often survived fossilization due to its hardness and durabilityothe study of past vertebrate life is mostly based on fossilsprovides reliable information about the specific adaptations of vertebrates-ex. posture, locomotor adaptationsgive shape to the body and support its weightoffers a system of levers that aid muscle movementsprotects soft parts-ex. nerves, blood vessels, etc.1.Endoskeleton: internal skeleton composed of hard, mineralized tissue thatenables movement by attachment of musclesformed deep within the body from mesoderm and othersourcesincludes connective tissue, bone, cartilage2.Exoskeleton: hard external skeleton that protects the outer surface of anorganismenables movement through the muscles attached on theinsideformed from or within the integumentdermis gives rise to bone and epidermis to keratinforms an important part of the endoskeleton in all vertebratesavascular tissue: devoid of any blood supply by arteries, veins or capillariestough, elastic, fibrous connective tissue found in various parts of thebody-ex. joints, epiglottis, outer ear, larynxcompromised most of the endoskeleton in higher vertebratesblood vessels and nerves are present in many bony tissues passing throughthe small Haversian canals-Haversian canals: located in the bone tissue at the center of thecompact bone, wherein blood vessels, nerve fibres, and lymph vesselspassOrganic component is primarily collagen-gives bone great tensile strengthInorganic components of bone comprise 60% of the dry weight
2 Components of skeletonCranial Skeleton: The SkullChondrocraniumFunctionssupport movement via attachments for soft tissue and muscleprotect vital organsmajor site for red marrow for reproduction of blood cellsplays role in metabolism of minerals-Ex. calcium, phosphorus2 basic structural types:1.Compact bone: used to create hard structures of skeleton2.Spongy bone/cancellous bone: porous type of bonehighly vascularized and contains red bonemarrowperiosteum: dense layer of connective tissue that surrounds the bone1.Cranial skeleton: the skullSplanchnocraniumChondrocraniumDermatocranium2.Postcranial skeleton:axial skeleton-vertebral column-notochordappendicular skeleton-limbs-girdlecomposite structure formed of 3 embryonic components1.chondrocranium2.dermatocranium3.splanchnocraniumunderlies and support the brainformed of endochondral bone or of cartilage, orboth which contributes to the bas of the skullprimary brain casesurrounds the brain and the special sense organsChondrocranium Ossification Centersoccipital centers: cartilage surrounding the foramenmagnum may be replaces by as many as 4 bones:1 basioccipital, 2 exoccipital, 1 supraoccipital
Dermatocranium6 centers-

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