Bone structure and function Flashcards
lecture 4 week 3
What are the functions of bones
- support
-protection
-movement
-storage (calcium and phosphate, growth factor, adipose cells) - blood cell formation
- acid base balance
- detoxification (take up heavy metals from blood)
- endocrine role (secrete osteocalcin)
What are the two types of bone tissue
- compact bone
- spongy bone
What are the components of bone catagorised into
- Acellular
- Cellular
What are the cellular components of bone and their function
Osteogenic: stem cells in the embryo that make osteoblasts
Osteoblasts: immature bone cells that secrete organic component of matrix
Osteocytes: mature bone that maintains the matrix
Osteoclasts: multinucleated cell, secretes acids and enzymes to dissolves bones which is needed for the repair and remodel of bones
What are the acellular components of bones and their function
- mineral matrix (inorganic)
70%
made of hydroxyapatite crystals (calcium phosphate)
gives strength to bones - osteoid matrix (organic)
30%
made of collagen
makes bones less brittle as protein makes the bones slightly flexible
What are the different types of bones
a. irregular bones eg. vertebrae and pelvis
b. short bones (cuboidal shape) eg. wrists
c. flat bones (narrow) eg. skull and sternum
d. long bones (longer than wide) eg. femure
e. sutural bones eg. additional bones
f. sesamoid bones (short bone in a tendon) eg. knee cap
What is the bone structure using a long bone as an example
made of a diaphysis (shaft) and epiphysis (bone ends)
diaphysis: compact bone, covered by a membrane periosteum (secured by Sharpey’s fibers), a cavity storage area for adipose tissue
epiphysis: covered by articular cartilage which cushions joints, contains epiphyseal line
What are the steps in endochondral ossification
i. a skeleton of cartilage forms from the embryo, the chondrocytes then die and are calcified
ii. blood vessels infiltrate the cartilage bone and the perichondrium differentiates to the periosteum
iii. osteoblasts then form from the periosteum
iv. a bone column forms from the osteoblasts
v. osteoblasts migrate to the center of the bone forming the primary ossification center making spongy bone
vi. all bone is then broken down forming the empty bone marrow cavity
vii. the secondary ossification center forms at epiphysis generating bone from osteoblasts and cartilage is replaced at the ends of the bone
What are the two classifications of joints
- functionally
- structurally
What are the growth factors in ossification
- Bone morphogenic proteins (BMPs)
- Insulin like growth factors (IGF)
- Transforming growth factor beta (TGF-B)
What are the different types of functionally joints
- synarthroses (immovable)
- amphiarthroses (slightly moveable)
- diarthroses (freely moveable)
What are the different types of structurally joints
- fibrous (fibrous tissue separates bone)
- cartilaginous (cartilage separates bone)
- synovial (bones separated by a cavity)
What is a fibrous joint
bones united by fibrous (collagenous) material
- suture (eg. skull) short fibers, immovable
- gomphosis (eg.teeth) immovable
- syndesmosis (eg. tibia, fibula connection) longer fibers, slightly moveable
What is a cartilaginous joint
bones connected by cartilage
- synchondrosis (eg. between sternum and 1st rib) hyaline cartilage, immovable
- symphysis (eg. vertebrae) fibrocartilage, slightly moveable
What are synovial joints
joints that are separated by a fluid cavity
- articular cartilage: hyaline cartilage covers bone ends
- articular capsule: comprises of an outer fibrous joint capsule and an inner synovial membrane
- joint cavity: a cavity within a joint contains synovial fluid
- ligaments: fibrous capsule enforced with ligaments
