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Chapter 6 Bones and Skeletal System Hyaline, elastic, and fibrocartilage help form the skeleton Skeletal cartilage Comprises the skeleton in early embryonic development – replaced over time by bone o Few cartilages remain in adults, but their job is still very important o Made of some variety of ________________ Consists primarily of ______________ o Contains no _______________ or ________________ vessels Surrounded by the __________________ o Dense irregular connective tissue o Resist outward expansion when the cartilage is compressed o Contains blood vessels to nourish the cartilage cells
Basic components of cartilage: o Cells called __________________ o Cavities within the ECM – called ___________________ Encloses the cells 3 Types: 1__________________ 2__________________ 3__________________ 1) Hyaline cartilage Provide support with flexibility and resilience Contain fine _____________ fibers that are not visible with a basic compound light microscope Comprises most skeletal cartilages: articular (joints), costal (rib cage), respiratory, and nasal 2) Elastic cartilages Resemble hyaline but have more _____________ fibers
2)_________________________
Lacunae-bound chondrocytes divide and secrete new matrix Expands cartilage ______________ the tissue Growth typically stops during adolescence when the skeleton stops growing Cartilage can become hardened due to deposits of calcium salts (calcified) o Calcified cartilage is NOT bone Bone Seven functions: 1_____________________________ 2_____________________________ 3_____________________________ 4_____________________________ 5_____________________________
6_____________________________
7_____________________________
Bone classification Two groups of bones in the skeleton: o ________________ Long axis of the body Bones of the skull, vertebral column, and rib cage Protect, support, and carry other body parts o ________________ bones of the upper and lower limbs and the girdles attach limbs to the axial skeleton help move from place to place (locomotion) and manipulate our environment
Sternum Scapulae Ribs Most cranial bones 4)________________ o Complicated shapes that fit none of the other classes o Examples: vertebrae and hip bones Bone structure overview Bones are considered ____________ because they contain different types of tissues Bone tissue is called ____________ tissue 5 Types of tissue in bones: 1______________: dominates bones 2___________________________ found in nerves 3__________________________ : found in articular cartilages 4___________________________ found on the external surface
5___________________________ found in the blood vessels Compact and spongy bone All bones consist of outer compact bone and inner spongey bone Gross anatomy: External layer: ________________ o Dense, solid, smooth outer layer Internal layer: ________________ o Small needlelike trabeculae (“little beams”) o In living bone, air spaces are filled with bone marrow (red or yellow) Short, irregular, and flat bones consist of: Thin plates of ____________ bone covered by _____________ bone Compact bone covered outside and inside by ________________ and ____________ (connective tissue membranes) No shaft or expanded ends
Located between _________________ and
Remnant of the epiphyseal plate (growth plate in children; disc of hyalin cartilage) Membranes of bones Periosteum o “peri” = _____________ o “osteum” = ______________ o Covers entire bone except for ________________ o Fibrous layer: _____________________ o Osteogenic layer: contains cells __________________ Primitive stem cells Give rise to most bone cells __________________
Bone destroying cells _________________ Bone forming cells o High in nerve fibers and blood vessels This is why breaking a bone hurts and bleeds o _______________ fibers: secure periosteum to underlying bone o Provides anchoring for tendons and ligaments Endosteum: the internal surface of bones o Covers _____________ bone surfaces o Covers trabeculae of spongy bone and lines canals passing through compact bone o Contains same cells types as osteogenic layer of the periosteum Blood vessels and nerves Bones are highly _______________
1______________________
2______________________
3______________________
4______________________
5______________________
1) Osteoprogenitor cells Mitotically active ________ cells Found in the ______________ and _______________ Stimulation: differentiate into __________________ 2) Osteoblasts Bone-forming cells Actively __________ Secrete ______________ bone matrix o Unmineralized bone = _____________________ o Collagen o Calcium-binding proteins
Play a role in matrix calcification (hardening) Active form: _______________ Inactive form: _______________ Become mature ________________ when completely surround by secreted matrix 3) Osteocytes Mature bone cells Occupy spaces called ______________ Function: __________________ and __________________ bone matrix Communicate information for bone _________________ to _______________ and ________________ o Which is responsible for bone resorption?
o Which is responsible for building up bone?
o Matrix tubes (tree rings): ____________ Collagen fibers run parallel in a single direction in one lamella Run opposite directions in adjacent lamellae Alternating pattern: resists torsional stress and twisting o Canals and caliculi Types: ________________ o Vascularized and innervated ________________ o Connect blood and nerve supply of medullary cavity to the central canals _______________ o Located at lamella (“tree ring”) junctions o Contain ________________
________________
o Connect lacunae to each other and to the central canal (blood and nerve supply) Interstitial and circumferential lamellae o Not part of complete osteons o Surround osteons or fill gaps between them Spongy bone microscopic anatomy Contain trabeculae o Resist ___________ No osteons are present Chemical bone anatomy consist of organic and inorganic components Organic components o _______________ o _______________
Why would having flexible structures fashioning the embryonic skeleton be important?
o Reminder: cartilage is replaced by bone, it is not converted into bone Two main processes of bone formation in fetus :1) _____________________ and 2)_____________________ 1) Endochondral Ossification Bone develops by ________________ hyaline cartilage Resulting bone is called an ________________________________ ( Develops all bones below base of skull, except
Uses hyaline cartilage models of the embryo as patterns for bone construction Endochondral Ossification: Step 1
Formation of ____________________ around diaphysis of hyaline cartilage model o Perichondrium is converted into __________________ Remember: perichondrium surrounds cartilage; it is dense irregular connective tissue, not cartilage connective tissue; cartilage is not converted into bone o Osteoid secretion against the hyaline ___________________ forms the bone collar o Chondrocytes within shaft ________________ (enlarge), generating the ___________________________________________ Endochondral Ossification: Step 2 Cartilage _______________ and develops __________________ Endochondral Ossification: Step 3 Formation of _______________ by invasion of periosteal bud into the internal cavities
