Bone Development Flashcards
Via what type of ossification do the skull bones form?
Intramembranous ossification
Intramembranous ossification mostly occurs in which bone types?
flat bone and some irregular bones.
How do the endosteum and periosteum ossify?
Via intramembranous ossification
Do children or adults have more alkaline phosphatase on average in their systems?
Children because their bodies are undergoing more bone development, in which calcification involves alkaline phosphatase.
Comparing cancellous vs. compact bone formation, upon forming trabeculae of bone, how do the two processes differ?
In cancellous bone formation, the spaces between trabeculae are filled with hematopoietic tissue; in compact bone formation, these trabeculae thicken and take up the spaces in between = compaction.
How are osteons formed?
Upon initial bone spicule formation, these will thicken and surround a blood vessel, forming a Haversian Canal around the blood vessel, and then later Volkman canals.
Endochondrial ossification occurs in which bone types?
Long, short, and some irregular bones.
Sort these in correct order: Secondary ossification site formation; collar formation; Periosteal BV/OPC invasion; hypertrophy; chondrocyte death; hypertrophic secretion; rest; proliferation; OPC–>OB–>Os
chondrocyte Rest, proliferate, bone collar formation, chondrocyte hypertrophy, hypertrophic secretion (coll X, EVGF), chondrocyte death, Periosteal BC/OPC invastion, OPC–>OB–>Osteod; secondary ossification site formation.
How can you tell between the zone of rest, proliferation, hypertrophy, calcification, and ossification?
rest has chondrocytes more spread out; proliferation you can see mitosis and higher cell density; hypertrophy has larger sized cells as they secrete TFs for BV invasion and collagen; calcification has blue calcified cartilage merging with red; ossification has red bone spicules forming.
In one length diaphysis region, as bone grows, is there higher or lower Ob/OClast activity on outer edge and inner edge?
As bone growth occurs, diaphysis outer edge has higher Ob/Oc ratio because bone is becoming wider. Inner edge has lower Ob/Oc ratio because osteoclasts are resorbing bone to maintain/increase bone marrow space.
Does Calcitonin regulate osteoblasts or osteoclasts? Does it increase or decrease its fxn? Does this increase or decrease serum Ca++ conc?
Calcitonin regulates osteoclasts, decreasing their activity, decreasing serum Ca++ conc.
Does PTH regulate osteoblasts or clasts? Increase/decrease its fxn? Incr/decr serum Ca++?
PTH regulates osteoclasts, increasing their activity, increasing serum Ca++ conc. Also increases GI Ca++ absorption and reduces kidney Ca++ excretion.
