Unit 2 Flashcards
Bone
- is mineralized, firm connective tissue
- is found only in vertebrates
Use of Bone (6)
- support
- leverage
- protection
- mineral reservoir
- sensory framework/insulator
- blood/immune cell production
Types of Bone Cells (4)
- Osteoblasts
- Osteocyte
- Osteoclasts
- Osteogenic cells
Osteoblasts
- responsible for forming new bone
- found in the growing portions of the bone
- incapable of mitotic division
- become osteocytes
Osteocyte
- primary cells of mature bone
- maintain the mineral concentration of matrix
- originate from calcified osteoblasts
Osteogenic Cells
stem cells that differentiate into osteoblasts
Osteoclasts
- responsible for bone resorption
- originate from monocytes and macrophages from osteogenic cells
- continually breaking down bone - can be used for releasing calcium stored in the bone
Classifications of Bone (5)
bone can be classified by:
1. shape
2. composition
3. formation
4. role
5. developmental/embryonic origin
Bone Shapes (5)
- long
- short
- Flat
- Irregular
- Sesamoid
Long Bones
- rectangular
- longer than they are wide
ex: femur, fingers, ribs
Short Bones
- relatively square
- about the same length as width
ex: carpals, tarsals
Flat Bones
“squamous” or thin
- can be curved
ex: sternum
Irregular Bones
odd, rough geometry
ex: vertebral, cranial
Sesamoid Bones
- small, roundish (oval), thick
- anchor joints
- look like sesame seeds
ex: patella
Bone Composition (2)
- Spongy Bone
- Compact Bone
Compact Bone
dense to withstand compressive forces
- in diaphysis
Spongy
(cancellous) bone has open spaces and supports shifts in weight distribution (more flexible)
- open network w/ trabeculae
- in epiphysis
Trabeculae
openings, spaces in bone
Osteons
Circular formations found in compact bone
Lamella
sheet/layer
Bone Marrow
makes immune cells
Flat Bone Layers (3 types)
Like a sandwich
- Periosteum
- Compact
- Spongy
- Compact
- Periosteum
Formation of Bone
- Endochondral Ossification
- Intramembranous Ossification
Endochondral Ossification (Long Bone)
- Cartilage develops and becomes calcified during fetal development
- Osteoblasts cover diaphysis
- Blood vessels bring osteoblasts into cartilage. Spongy bone forms at primary ossification center
- Medullary cavity forms, secondary ossification center forms in epiphysis
- Growth continues through childhood while cartilage is present at growth plates