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2/15 quiz LEC
2/15 quiz LEC - Skeletal Tissue
Question | Answer |
---|---|
Skeletal Tissue functions (6) | Support, Protection, Movement facilitation, Mineral Storage (CA,P), Blood Production, Store energy (fat) |
Histology is | the study of tissue |
Connective Tissue Cell Hisology includes (3) | Osteoprogenitors, Osteoblasts, Osteoclasts |
Osteoprogenitors | UNSPECIALIZED cell in embryo from which all bones are derived. Can differentiate into osteroblasts & osteoclasts |
Osteoblasts | Bone-Forming cells. Become osteocytes when trapped by their own matrix |
Osteoclasts | Bone-Dissolving cells |
Connective Tissue Matrix Hisology (2) | 67% Mineral Salts & 33% Collagenous Fibers |
Mineral Salts in the matrix are called | Hydroxyapatite - HARD. CA & P |
Collagenous Fibers in the matrix give | shape |
Diaphysis | shaft |
Epiphysis | end |
Articular Cartilage | hyaline cartilage. covers the epiphyses. |
Periosteum | collagenous (dense fibrous) CT covering bone surface (but not articular cartilage) |
Medullary / Marrow cavity | Red marrow in children. Yellow marrow in adults. |
Endosetum | collagenous tissue lining marrow cavity |
epiphyseal plate | growth plate. cartilage in a child |
Epiphyseal Line | bone - in an adult |
Ossification | Bone Formation |
Type of Ossification | Intramembranous & Endochondral methods |
Intramembranous & Endochondral methods appearance | identical |
Intramembranous Method | bone made over a fibrous membrane |
Endochondral Method | replaces cartilage |
Intramembranous Ossification (2) | 1. Osteoprogenitor cells leave blood & invade fibrous membrane. 2. Oseoprogenitors become Osteoblasts & make bone. Become Osteocytes when trapped in their own bony material. |
Intramembranous Ossification forms | Surface skull bones & clavicles (collar) |
Fontanels are | soft spots of fibrous tissue not yet ossified in the skull of newborn (Intramembranous Ossification) |
Osteoprogenitor cells | lay down bone |
Osteons are | tough b/c membranous - Intramembranous Ossification? |
Endochondral Ossification (1-4) | 1. Most of skeleton initially cartilage covered with membranous perichondrium. 2. Blood delivers Osteoprogenitors to Diaphysis. 3. Bony collar forms 4. Cartilage cells in center diaphysis swell up & die. |
Endochondral Ossification (5-8) | 5. blood vessels invade delivering osteoprogenitors. 6. osteoprogenitors become osteoblasts forming promary ossification center. 7. Bone formation continues up and down diaphysis. 8. Same thing happens in epiphysis forming 2ndary ossification center |
2 areas not replaced by bone in Endochondral Ossification | articular cartilages & epiphyseal plates |
all remaining bones formed by | Endochondral Ossification |
bony collar | where osteoprogenitors invade |
significance of cartilage being devoid of blood vessels | nutrition is diffused from the blood or adjacent tissues. **HEALS SLOWLY |
bone growth occurs which way and where | length (end result) @ the epiphyseal plate |
during bone growth, cartilage cells at the epiphyseal end | proliferate (moves up - mitosis) |
during bone growth, cartilage cells at the diaiphyseal end | die and are replaced by bone |
which happens faster? epiphyseal proliferation or diaiphyseal death during bone growth | diaiphyseal death & bone replacement |
when the plate disappears & what avg age? | fusion --> epiphyseal line. avg age 22-23 yrs |
when is bone growth in length no longer possible | when fusion occurs |
growth at the plate is affected by | growth hormone (GH) |
lack of GH (child) | dwarfism |
lack of GH (adult) | we dont know |
excess GH (child) | giantism |
excess of GH (adult) | acromegaly |
how sex hormones affect growth | stimulate rapid growth at puberty & can cause early plate fusion(22-23) |
castration does what | lessens sex hormones - castrated man avg shorter height |
growth in width (3) | periostem lays down bone & endosteum destroys bone (with osteoclasts) enlarging the bone marrow cavity. (sound, strong structure) |
bone is always | remodeling - replacing old bone with new |
why does bone remodel | everything eventually wears out |