Bone Development

Question 1

T/F: Intramembranous ossification involves a hyaline cartilage model precursor.

Answer 1

False. Endochondral ossification uses a hyaline cartilage precursor.

Question 2

T/F: Intramembranous ossification takes place in long bones.

Answer 2

False. Intramembranous = flat and irregular bones

Endochondral = long bones

Question 3

What is the first step in endochondral ossification?

Answer 3

The fetal hyaline cartilage calcifies and periosteal bone collar forms around the diaphysis.

Question 4

Soon after formation of the bone collar, what forms in the diaphysis?

Answer 4

Primary ossification center

Question 5

_______ ossification center forms in the diaphysis, while _______ ossification centers form in the epiphysis.

Answer 5

Primary; secondary

Question 6

What parts of the hyaline cartilage are not replaced with bone during endochondral ossification?

Answer 6

Articular cartilage at the ends of the epiphysis, and the epiphyseal plates (growth plates).

Question 7

What is the very last step of endochondral ossification that takes place at the end of puberty?

Answer 7

Epiphyseal plates ossify into the epiphyseal lines.

Question 8

From epiphysis to diaphysis name the 5 zones of the epiphyseal plate.

Answer 8

Rick Pissed His Cat Off
Zone 1: resting cartilage
Zone 2: proliferating cartilage
Zone 3: hypertrophic cartilage
Zone 4: calcified cartilage
Zone 5: ossification

Question 9

What is the pathway for storing calcium in bone?

Answer 9

High levels of blood Ca2+ -> thyroid gland releases calcitonin -> calcium salt deposit into the bone

Question 10

What is the pathway for the release of calcium from the bone?

Answer 10

Low levels of blood Ca2+ -> parathyroid glands release PTH -> osteoclasts degrade bone matrix and release Ca2+ into blood

Question 11

What two controls impact bone remodeling?

Answer 11

1. Calcium homeostasis (WHEN remodeling occurs)

2. Bone’s response to mechanical stress & gravity (WHERE remodeling occurs)