Lecture 10 Flashcards
When does bone ossification occur?
The 8th week of pregnancy till early 20s
What was bone prior to ossification in pregnancy?
Fibrous membranes and hyaline cartilage
How do bones become hard?
By intramembranous or endochondral ossification
What bones are created from intramembranous ossification?
Flat bones (ex. Clavicle, skull, mandible)
Few bones
How are bones intramembranous ossified?
Fibrous connective tissue -> osteoblast to make spongy bone at connective lines -> periosteum forms and compact bone beneath
How are endochondral ossification bones formed?
Hyaline cartilage ossifies -> spongy from -> periosteum forms and makes compact bone beneath
What is the epiphyseal plate?
Where bone growth occurs by mitosis
Does not ossify
What parts of the bone do not ossify?
Articulate cartilage and epiphyseal line
How do bones growth in length postnatal?
Expanding at the epiphyseal plate and ossifying the plate to become the epiphyseal line
How do bones grow in diameter postnatal?
Osteoblasts beneath the periosteum secrete bone matrix -> osteoclasts reabsorb bone on inner cavity to make room for more spongy bone
What factors affect bone growth?
Mechanical stress
Nutrition
Hormones
How can bone healing rate be increased?
Using weights or electrical current to activate osteoblasts activity
How does mechanical stress affect bone growth?
Mechanical stress forces more osteoblasts to make thicker and wider bones for heavy lifting and exercise
restricted movement inhibits osteoblasts but not osteoclasts which will result in low bone density
How does nutrition affect bone growth?
Ca+ and PO4- for matrix production
Vit C for collagen production
Vit D for absorption of Ca+ from intestines
What bone disease can result in soft bones? Why?
Rickets. Lack of Vit D therefore lack of Ca+ absorption for bone collagen
