Chapter 6 Bones and Skeletal Tissues
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Describe the two main regions of the skeleton.
- Axial- skull,vertebral,column,rib cage
- Appendicular- limbs, girdles,locomotion/movement
Describe where cartilage is found on the skeleton of an adult, and what type of cartilage is found in each location.
Joint areas or where a bone is meeting with another bone. Three types found hyaline,elastic,and fibrocratilage.
Describe the two mechanisms by which cartilage can grow.
- Endochondral Ossification=Bone replated by hyaline cartilage.
- Intramembranous Ossification=bone develops from a fibrous membrane(only cranial bones and clavicles are formed this way)
What is the name of the membrane that wraps cartilage? What is it made of?
- Perichondrium wraps cartilage
- Dense, Irregular tissue
Describe the four main classifications of bones; for each type, give one example of where it can be found in the body.
- Long bones- shat+ 2 ends, most bones in limbs (Humerus)
- Short bones-cube shape, wrists/ankels (talus)
- Flat bones- thin,flattened,curved (ribs) most skull bones
- Irregular bones-complicated shapes,vertebrae,hip bones
Name and describe the 6 main functions of bones.
- Support: Structural framework for the body
- Protection:cranial bones protext brain,vertebrae protext spinal cord, rib cage protects heart and lungs
- Movement: most skeletal muscles attach to bones by tendons and use bones as levels from movement
- Mineral storage: reservoirs for calcium and phosphorous
- Blood cell production:certain bones contain red bone marrow the site of hematopoiesis (the formation of all blood cels)
- Triglyceride storage:certain bones contain yellow bone marrow which consists mainly of adipose cells
Why are bones considered to be "organs"?
Bones are considered organ because they have cells and tissues.
Describe in detail the structure of long bones. Your answer should include: diaphysis, epiphyses, epiphyseal line, periosteum, endosteum.
- Diaphysis: shaft, thick collar of compact bone, central medullary cavity (yellow bone marrow)
- Epiphyses: Bone ends, outer shell=compacts bones, interior=spongy bone, articular cartilage (hyaline) covers joint surface
- Epiphyseal line: Remnant of epiphyseal
- Periosteum: External bone membrane
- Endsteum: Internal bone membrane
How does the gross anatomy of long bones differ from short, flat, and irregular bones?
- Does not have shaft or epiphyses
- Does not have medullary cavity
Describe in detail the organic and inorganic components of bone.
- Organic components: 35% by mass
- Osteoid:organic part of extracellular matrix, ground substance (proteoglycans and glycoprotiens), collagen fibers (made by osteoblasts)
- Inorganic components: (65% by mass) Mineral slats (mostly calcium phosphate) Produce hardness of bone
What are the 4 cell types found in bone, what are their main functions?
- Osteogenic cells: mitotically active stem cell, found in membranes (periosteum and endosteum)
- Osteoblasts: immature cells; secrete bone matrix
- Osteocytes: mature cells; occupy lacunae; maintain bone matrix
- Osteoclasts:large multinucleated cells that breakdown bone
Describe in detail the microscopic anatomy of compact bone. Your answer should include the structure and function of the osteon. Your answer should include: Haversian canal, Volkmann's canal, and canaliculi.
- Haversian:(central canal) blood vessels and nerve fibers
- Volkmann's:(perforating canals) connect blood supply of osteons to medullary cavity
- Canaliculi:Hair like canals that connect lacunae, allow osteocytes to communicate via gap junctions
Describe the process of endochondrial ossification. How does this differ from intramembranous ossification?
- Endochondral Ossification: bone replaced by hyaline cartilage
- Intramembranous Ossification:is when bone develops froma fibrous membrane but only happens in cranial bones and clavicles are also formed this way)
Describe in detail how post-natal growth of long bone works, including the role of “remodeling” in maintaining proper bone shape and proportions.
- (Occurs at epiphyseal plate and articular cartilage)
- Growth in length: Intersitial (chondrocytes and osteoblasts from withing)
- Growth in width:s appositional (osteoblasts beneath periosteum.
- Bone remodeling: Maintains bone proportions, involves bone formation and reabsorption
What is the purpose of regular bone remodeling? How often does it occur?
- Bones are dynamic organs:5-7% of bone mass is recycled every week
- Spongy bone is replaced every 3-4 years
- Compact bone is replaced every 10 years
- The purpose of regular bone remodeling is to maintain homeostasis
Describe the two mechanisms involved in bone remodeling.
- Osteoblats: Deposit new bone matrix
- Osteclasts: Breakdown and reabsorb bone matrix
Describe the role of parathyroid hormones in the control of blood calcium levels and bone remodeling.
The role of parathyroid hormones is to stimulate the osteoclasts in response to the amout of calcium levels. The more parathyroid hormones the most osteoclasts know how much to secreate the less hormones the less amount of bone that are being secreated
Describe how mechanical stress affects bone deposition.
- Bones structure reflects physical demands:
- Loading results in bending and bending results in growth.
- Bones are thicker where they are most likely to buckle or break .
Describe the 6 types of fractures discussed in table 6.2
- Comminuted: Bone fragments into three or more pieces
- Compression:Bone is crushed
- Spiral:Ragged break occurs when excessive twisting forces are applied to a bone.
- Epiphyseal: Epipysis separates from the diaphysis along the epiphyseal plate
- Depressed: Broken bone protion is pressed inward
- Greenstick:Bone breaks incompletely, much in the way a green twig breaks. Only one side of the shafts break the other side bends.
Describe how fractures are classified.
- Position of bone after fracture, non-displaced vs.displaced
- Completeness of break complete vs. incomplete
- Penetration of skin open (compound) vs. Closed (simple)
- Fractures cam also be described by location,external appearance, and/or nature of the break
Describe osteoporosis: What is it? What causes it (especially in women)? What is the effect of exercise?
- Osteoporosis: Occurs when bone reabsorption happens faster than bone deposit.
- Sex hormones:(estrogen in females) restrain osteoclasts and promote bone deposit.
- Exercise helps promote bone growth and is very effective against bone degeneration
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