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Chapter 6
The Skeletal System: Bone Tissue
| Question | Answer |
|---|---|
| What are the functions of bone? | -Support soft tissue -attachment of skeletal muscles -protection -reservoir -hemopoiesis -storage |
| What do bones support? | soft tissue |
| How does the attachment of skeletal muscles work? | attachment via tendons |
| When muscles contract what happens? | movement results |
| what does the skeletal system protect? | vital organs such as central nervous system housed in cranial cavity and vertebral column |
| what does the skeletal system hold in reserve? | minerals such as calcium and phosphorus |
| what is hemopoiesis? | the manufacture of blood cells in red bone marrow |
| what does a bone store? | triglycerides |
| what are the 5 types of bones? | -long bones -short bones -flat bones -irregular bones -sesamoid bones |
| what is a long bone and examples | bones longer than they are wide femur, humerus, phalanges |
| what is a short bone and examples | cube shaped wrist and ankle |
| what is a flat bone and examples | thin, flattened and a bit curved sternum, scapula, ribs and skull |
| what is an irregular bone example | vertebrae and hip bones |
| what is a sesamoid bone and examples | develop in tendons and under stress patella |
| what is the diaphysis of a long bone? | shaft - hollow in the middle and contains mostly marrow |
| what is the medullary cavity of a long bone? | marrow cavity - runs length of diaphysis and usually contains yellow marrow |
| yellow marrow stores what in adults? | triglycerides |
| what is the epiphysis of a long bone? | ends of bone |
| where is red marrow found? | in proximal epiphysis (ends) of humerus and femur |
| where is yellow marrow found? | in all other epiphysis (ends) of bones but the humerus and femur |
| what is the metaphysis of a long bone? | between diaphysis and epiphysis |
| what is the epiphyseal plate of a long bone? | a layer of hyaline cartilage that allows the diaphysis to grow in length....a growth plate |
| what is the epiphyseal line of a long bone? | bony structure that replaces epiphyseal plate when bone stops growing |
| what is the periosteum of a long bone? | outside covering of bone except at join surface present in 2 layers |
| what is the inner layer of the periosteum consist of? | single layer that contains opteoprogenitor cells and osteoblasts |
| what is the outer layer of the periosteum consist of? | made of dense irregular CT vascular layer because it contains blood vessels, lymph vessels, and nerves that pass into the bone also serves as points of attachment of tendons and ligaments |
| what is the endosteum of a long bone? | usually a single layer of cells that lines medullary (marrow) cavity, Haversain, Volkmans canals and covers trabeculae of spongy bone |
| what does the endosteum contain | osteoblasts and osteoclasts |
| what is the articular cartilage of a long bone? | hyaline cartilage that covers the articular surface of each epiphysis |
| what prevents friction and damage at joints? | articular cartilage |
| what are the 4 bone cells? | osteoprogenitor osteoblasts osteocytes osteoclasts |
| what are osteoprogenitor cells? | derived from mesenchyme capable of mitosis and develops into osteoblasts located in inner periosteum, endosteum, Volkmans and Haversian cannals |
| what are osteoblasts | not capable of mitosis produce collagen |
| what do osteocytes do? | maintain bone |
| what are osteoclasts? | bone digesting cells develop from monocytes and release collagenase (digest collage) and acids that digest bones |
| ostogenic cells | osteoprogenitor |
| derived from mesenchyme | osteoprogenitor |
| capable of mitosis and develop into osteoblasts | osteoprogenitor |
| not capable of mitosis | osteoblasts |
| produce collagen | osteoblasts |
| maintain bone | osteocytes |
| digest bone | osteoclasts |
| by weight bone has ___ water, ___ collagen fibers, and ___ calcium phosphate | 25% 25% 50% |
| what do collagen fibers produce? | osteoblasts |
| when osteoblasts are trapped in lacuna what are they called? | osteocytes |
| cytoplasmic extensions from osteocytes are located in _______ | canaliculi |
| how do nutrients reach osteocytes? | via canaliculi and cytoplasmic extensions from Haversain canal |
| what is the concentric rings around a Haversain canal called? | lamella |
| what makes up the Haversian system (osteon)? | Haversian canal and surrounding lamella |
| how does soft bone differ from compact bone? | has latticework of thin bone plates (trabeculae) within trabeculae are lacunae with osteocytes that are connected by canaliculi osteocytes are nourished directly from blood |
| what do some spaces between trabeculae contain? | red bone marrow capable of hemopiesis |
| what are trabeculae? | beams of bone in spongy bone |
| what is bone formation called? | ossification |
| when does ossification begin/ | 6th week of embryonic life |
| what do bone cells develop from? | mesenchymal cells |
| when mesenchyme migrate into area that form bone what happens? | they either form chondroblasts if no capillaries or osteobalsts if capillaries |
| what does ossification replace? | preexisting connective tissue |
| intramembranous means | inside membrane |
| intramambranous formation occurs in.... | flat bones of skull and part of clavicle |
| when does intramambranous formation occur? | begins at 6 weeks of embryonic life |
| what happens during intramembranous formation with mesenchyme cells? | mesenchyme cells in fibrous membrane differentiate into osteoblasts that secrete collagen |
| what happens during intramembranous formation after the collagen is secreted? | osteoblasts secrete an enzyme that encourages deposit of Ca2+ salts along collagen |
| after collagen is secreted and the Ca2+ salts are deposited, what three things happen next during intramembranous formation | trabeculae form and fuse with other trabeculae osteoblsts become osteocytes and are trapped withing lacunae spaces between trabeculae fill with marrow |
| the outside covering of bone becomes ____________ during intramembranous formation | 2 layered periosteum |
| what do surface layers of intramembranous bone eventually reconstruct to and why? | surface layers eventually reconstructed into compact bone because osteoblasts on surface reconstruct bone (much of newly formed bone will be destroyed and reformed) |
| at birth, those areas of membrane that have not yet ossified are the _________ | fontanels |
| what do all endochondral formation start off as? | as hyaline cartilage except skull and part of clavicle |
| endochondral formations give rise to...... | all other bones |
| when does endochondral formations start? | at 8 weeks of embryonic life |
| what does endochondral mean? | inside cartilage |
| describe the hyaline cartilage model. | it is covered with perichondrium and is first formed and is repalced by bone |
| the primary ossification center is .... | the center of the bone |
| what do blood vessels in the primary ossification center do? | they penetrate the perichondrium in the center of the diaphysis and stimulate osteoprogenitor cells of internal layer of perichondrium to enlarge and become osteoblasts |
| once perichondrium starts to produce bone is it called...... | periosteum |
| after blood vessels penetrate the perichondrium what happens in endochondral formation | osteoblasts then form a thin layer of calcified bone tissue under the periosteum, the bony collar and secrete an enzyme which encourages Ca2+ salts to deposit in the matrix |
| what does the bony collar and the newly calcified matrix do? | they restrict nutrient flow to the existing chondrocytes, the cartilage cells hypertrophy because nutrients cannot diffuse to the chondrocytes and they die causing cavities to form |
| what happens in the cavities in endochondral formation? | either osteoblasts form new spongy bone tissue or osteoclasts digest out more cavity, forming marrow cavity of disphysis |
| what happens in the secondary ossification center? | more blood vessels enter the epiphysis, bringing with it osteoprogenitor cells that develop into osteoblasts which produce spongy bone |
| when do secondary centers begin? | after birth |
| what happens after the secondary centers have formed? | bone tissue completely replaces cartilage except in two regions -articular cartilage -ephiphyseal plate |
| where is articular cartilage | ends of long bones where you move |
| where is an epiphseal plate? | eventually goes away at puberty, every bone has one |
| bones grow in length by the __________ | epiphyseal plate |
| what are the 4 zones of the epiphyseal plate | zone of resting cartilage zone of proliferating cartilage zone of hypertophic cartilage zone of calcified cartilage |
| ephiphyseal side | zone of resting (quiescent) cartilage |
| mitosis | zone of proliferating cartilage |
| cartilage cell enlarging | zone of hypertophic cartilage |
| dying cartilage cells on diaphyseal side | zone of calcified cartilage |
| what happens to epiphyseal cartilage at puberty? | it stops dividing and is replaced by bone at puberty with surge of hormones; what remains is the epiphyseal line |
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mastrgurl
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