Bone
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56 terms
Terms | Definitions |
|---|---|
 compact bone | dense outer layer |
| spongy bone | internal to compact bone network (trabeculae) |
| trabeculae | the irregular latticework of thin bony plates in spongy bone tissue red or yellow marrow |
| medullary cavity contains.. | marrow |
| epiphyses | 1. expanded ends of long bones 2. exterior is compact bone, and the interior is spongy bone 3. joint surface is covered with articular (hyaline) cartilage 4. Epiphyseal line separates the diaphysis from the epiphysis. |
| diaphysis | shaft of a long bone compact bone surrounds medullary cavity |
| Periosteum | outer- dense irregular connective tissue inner- osteoblasts and osteoclasts nerve fibers/blood/lymphatic vessels -nutrient foramina |
| nutrient foramina | minute holes in the bone surface that allows blood vessels to penetrate |
| sharpey's fibers | Collagen fibers which penetrate the bone. The attachment is so strong that even with severe traction injuries the tendon usually does not "pull out" of the bone but instead either tears or a fragment of bone is pulled out with the inserted collagen fibers (known as an avulsion fraction). |
| Endosteum | Connective tissue membrane covering internal bone surfaces -covers trabeculae -lines canals -contains osteoblasts/osteoclasts |
| Structure of short, irregular, flat bones | compact bone on the inside spongy bone (diploe) on inside no diaphysis/epiphyses bone marrow between trabeculae |
| location of red marrow: infants | found in medullary cavity and all areas of spongy bone |
| location of red marrow: adults | found in dipole of flat bones and the head of the femur and humerus |
| haversian system | Central canals surrounded by osteons; contain the blood vessels and nerves that serve the bone |
| lamellar bone | mature bone present in normal adult stages; collagen fibers are perfectly arranged in a parallel pattern so they can withstand torsional stress |
| lamellae | Concentric rings made up of groups of hollow tubes of bone matrix |
| Volkman's canals | Channels lying at right angles to the central canal, connecting blood and nerve supply of the periosteum to that of the Haversion Canal |
| Osteocytes | Mature cells, develop from osteoblasts, control day-to-day activities (each occupies a lacuna, a pocket sandwiched between layers of matrix |
| lacunae | small spaces between the lamellae which contain osteocytes |
| canaliculi | small hair-like canals extending from the central canal. Allow for diffusion of nutrients, waste products, hormones, etc. to lacunae. |
| Strength: Compact Bone | located where stressed are limited in direction |
| Strength: Spongy Bone | located where stresses are weaker or multi-directional |
| How to trabeculae help with bone stress | they line up alone the line of force to help deal with multi-direction foraces |
| osteoblasts | bone forming cells - perimeter of bone |
| osteocytes | maintain bone - inside bone |
| osteoclasts | large cells that resorb or break down bone matrix, releasing calcium ions into the blood - perimeter of bone |
| osteoid | Unmineralized bone matrix composed of proteoglycans, glycoproteins, and collagen |
| hydroxyapatites | mineral salts; calcium phosphate & Salts |
| Without minerals bone... | is flexible |
| without collagen bone | shatters |
| how does ossification through age? | embryo - ossificaiton -> bone formation early adulthood - ossification -> bone growth adult - ossification -> bone remodeling/repair |
| Intramembranous ossification | Bone growth within a membrane (mesenchyme) Forms flat bones of the skull, some facial bones, mandible, and clavicle |
| endochondral ossification | the most common bone formation process, which involves the replacement of hyaline cartilage (developed by mesenchyme) with bone |
| Long bone growth | Cartilage proliferation on epiphyseal side of epiphyseal disk • Ossification (conversion to bone) occurs on diaphyseal side of epiphyseal disk |
| rate of bone growth... | outpaces that of cartilage growth |
| bones: sex hormones | estrogen and testosterone tell you when to stop growing. gives qualities of male and female. |
| bones: thyroid hormones | remodeling of bone |
| bones: growth hormones | encourages general growth |
| appositional growth | growth at the outer surface of a bone during endochondral ossification, resulting in an increase in the bone's THICKNESS, Compact bone thickens and strengthens long bone with layers of circumferential lamellae |
| Vitamin A | stimulates osteoblasts |
| Vitamin C | needed for collagen |
| Vitamin D3 | cholecalciferol, In the presence of Sun; epidermal cells produce cholecalciferol (vit D3)...the liver and kidneys convert D3 into Calcitriol (important in bone & nerve conduction; and aids in absorption of calcium and phosphorus) |
| bone resorption | process of bone demineralization or the breaking down of bone into mineral components osteoclasts secret -lysosomal enzymes -acids |
| calcium is needed | Needed for: 1. The process of bone formation 2. Coagulation of blood 3. Excitation of cardiac and skeletal muscle 4. Maintenance of muscle tone 5. Conduction of neuromuscular impulses 6. Synthesis and regualtion of the endocrine and exocrine glands |
| Control of Remodeling | controlled by Hormonal mechanisms that maintain calcium homeostasis in the blood, and Mechanical and gravitational forces |
| Rising blood Ca triggers | thyroid to release calcitonin stimulates calcium salts to be deposited in bone |
| calcitonin | reduces blood calcium level |
| Falling blood Ca triggers | parathyroid gland to release PTH, osteoclasts to degrade bone and release Ca into blood |
| PTH | Parathyroid hormone; secreted by the parathyroid gland; PTH regulates uptake of calcium (Ca) from the bones into the blood |
| Wolff's Law | A bone grows or remodels in response to forces or demands placed upon it |
| Wolff's law | Curved bones are thickest where they are most likely to buckle Long bones are thickest midway along the shaft (bending stress is greater) + hollow or filled with far Large bony projections occur where heavy, active muscles attach |
| Stages of Healing of a bone Fracture | hematoma formation (mass of clotted blood), fibrocartilaginous callus formation (soft tissue forms & phagocytic cells begin cleaning debris), bony callus formation (Osteoclasts remove dead cells & cartilage & osteoblasts secrete new matrix) Bone Remodeling |
| osteomalacia | abnormal softening of bones caused by deficiencies of phosphorus or calcium or vitamin D |
| rickets | childhood disease caused by deficiency of vitamin D and sunlight associated with impaired metabolism of calcium and phosphorus |
| osteoporosis | abnormal loss of bony tissue resulting in fragile porous bones attributable to a lack of calcium |
| paget's disease | a bone disease of unknown cause characterized by the excessive breakdown of bone tissue, followed by abnormal bone formation |
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