Bone Tissue Flashcards
CHAPTER 7
Skeletal cartilages (3)
- Hyaline Cartilages: provide support, flexibility, and resilience, MOST abundant, end of long bones (trachea, ribs)
- Elastic cartilages: similar to hyaline cartilages, but contain elastic fibers (ear, epiglottis)
- Fibrocartilages: collagen fibers –> have great tensile strength (invertebrate discs, knee caps)
Cartilage found in between joints which are where bones are connected for movement
Growth of cartilage (3)
- Appositional (grows from outside - width)
- cells secrete matrix against external face of existing cartilage - Interstitial (grows from inside - length)
- Chondrocytes divide and secrete new matrix, expanding cartilage from within - Calcification of cartilage occurs during normal bone growth, old age, and calcified cartilage is NOT BONE
Classification of bones by shape (4)
- Long bones: longer than they are wide
- Short bone: cube shaped bones (wrist and ankles), sesamoid bones (within tendons, patella)
- Flat bones: thin, flat, slightly curved (skull, scapula, sternum)
- Irregular bones: complicated shapes (vertebrae, pelvis)
How many bones in human body?
206 bones
- fetus has more bones but fuse as one bone as you grow
Functions of bones (6)
- Support for the body and soft organs
- Protection for brain, spinal cord, and vital organs
- Movement levers for muscle action
- Storage: minerals (calcium + phosphorus) and growth factors
- Blood cell formation (hematopoiesis) in marrow cavities
- Triglyceride (energy) storage in bone cavities
Bone markings
- Bulges, depressions, and holes serves as…
- sites of attachment for muscles, ligaments, tendons
- joint surfaces
- conduits for blood vessels and nerves
- helps you understand the function of many bones
What are the sites of muscle + ligament attachment? (8)
- tuberosity: rounded projection
- crest: narrow, prominent ridge
- trochanter: large, blunt, irregular surface
- line: narrow ridge of bone
- tubercle: small rounded projection
- epicondyle: raised area above a condyle
- spine: sharpe, slender projection
- process: any bony prominence
Projections that form joints (4)
- Head: bony expansion carried on a narrow neck
- Facet: smooth, nearly flat articular surface
- Condyle: rounded articular projection
- Ramus: armlike bar
Depressions + openings (6)
- Meatus: canal-like passageway
- Sinus: cavity within a bone
- Fossa: shallow, basin-like depression
- Groove: furrow (bicipital)
- Fissure: narrow, sitlike opening
- Foramen: round/oval
2 types of bone textures
- Compact bone (10 years)
- dense outer layer - Spongy cancellous bone (3-4 years)
- honeycomb of trabeculae
- more porous like a sponge
2 membranes of bone
- Periosteum
- outer fibrous layer
- inner osteogenic layer
- osteoblasts (bone forming cells)
- osteoclasts (bone destroying cells)
- osteogenic cells (stem cells) - Endosteum
- delicate membrane on internal surfaces of bone
- also contains osteoblasts and osteoclasts
Structure of short, irregular, and flat bones
- periosteum covered compact bone on the outside
- endosteum covered spongy bone within
- spongy bone called diploe in flat bones
- bone marrow between the trabeculae
location of hematopoietic tissue (red marrow)
- red marrow cavities of adults
- trabecular cavities of the heads of the femur and humerus
- trabecular cavities of the diploe of flat bones
Microscopic anatomy of bone and its 4 types
-cells of bones
- osteogenic (osteoprogenitor) cells: stem cells in periosteum and endosteum that give rise to osteoblasts
- osteoblasts: bone-forming cells, secrete bone matrix
- osteocytes: mature bone cells, monitor/maintain matrix
- osteoclasts: cells that break down (resorb) bone matrix
Compact bone and 4 types
- Haversian system (osteon): structural unit
- Lamellae: concentric rings, weight bearing, column like matrix tubes (collagen)
- arranged in diff directions to maintain strength
- central (haversian) canal: contains blood vessels and nerves - perforating (volkmann’s) canals: at right angles to the central canal, connects blood vessels and nerves of the periosteum + central canal
- lacunae: small cavities that contain osteocytes
4: canaliculi: hairlike canals that connect lacunae to each other and the central canal (adj. osteocytes communication)
Spongy bone
Trabeculae
- align along lines of stress
- no osteons
- contain irrgularly arranged lamellae, osteocytes, and canaliculi
- capillaries in endosteum supply nutrients
Organic composition of bone
- osteogenic cells, osteoblasts, osteocytes, osteoclasts
osteoid: organic bone matrix secreted by osteoblasts
- ground substance: proteoglycans, glycoproteins
- collagen fibers: provide tensile strength + flexibility
Inorganic composition of bone
- hydroxyapatites (mineral salts)
- 65% bones by mass
- mainly calcium phosphate crystals
- responsible for hardness + resistance to compression
