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
Intramembranous Ossification (Flat Bones)
- Condensation of Mesenchyme
- Deposition of osteoid tissue by osteoblasts - form periosteum
- Honeycomb of bony trabeculae, mineral deposition, form spongy bone
- Surface bone filled by bone deposition, compact bone forms around spongy bone middle
Dermal Bone
- very dense
- good at protection
- okay to keep in water (aquatic animals)
- very heavy (bad for land animals)
Foramina
- openings, holes, or passages especially in the bone
- allow passages of nervous vascular elements through bone
Roles of the Skull (4)
- support and protect sensory organs
- support and protect brain, CNS
- support, reflect feeding and feeding mechanism
- support, reflect respiration and respiratory mechanism
Evolutionary Skull
- previously, only role was protecting sensory organs
- developed the eye socket, ability to chew
Difficulties of a “helmet” skull
- no accommodation for swelling
- no where to let information exit
Functions of Cranial Bones (2)
- surround and protect the brain
provide extensive area for muscle attachment (move eyes, jaw, and head)
Functions of Facial Bones (3)
- protect and support entrances to the digestive and respiratory tracts
- actively involved in respiration and mastication (chewing)
- provide areas for muscle attachment that control facial expressions
Occipital Bone
the single bone that forms the posterior (back) of the skull and the posterior base of the cranial cavity
holds foramen magnum and occipital condyles
- site of attachment for neck muscles
Condyle
“knuckle” a round prominence at the end of a bone, often a joint
Frontal Bone
unpaired bone that forms the forehead, roof of orbit, and floor of anterior (internal) cranial fossa, frontal sinuses