Skeletal System pt. 2

Microscopic Structure of BonesBone Development

Agenda• Do Now• Introduce: Microscopic Structure of Bone • Bone Matrix Diagram• Introduce: Bone Growth and Development• Assign: Chapter Project• Homework Question• Exit Ticket

Microscopic Structure• Osteocytes (osteo-: bone, -cyte:

cell) are located in small cavities in the matrix called lacunae.

• The extracellular (extra-: outside) matrix in bone tissue is hard material composed of collagen and inorganic salts

• Bones also contain nerves (ouch!) and blood vessels.

Microscopic Structure• Lacunae are connected by canaliculi (singular:

canaliculus). This is how the cells share nutrients and communicate.

• Where do the blood vessels and nerves come in? o Lacunae are arranged in concentric (co:- same, -centric:

center) circles around osteonic canals.

o The group of rings that share the same osteonic canal are called an osteon

o The vertical osteonic canals are connected transversely by communicating canals.

Whiteboard Practice

Multiple ChoiceA: OsteonB: Osteonic CanalC: Periosteum D: Spongy Bone

?

Multiple ChoiceA: LacunaB: Osteonic CanalC: Periosteum D: Spongy Bone?

Multiple ChoiceA: OsteonB: Osteonic CanalC: Periosteum D: Spongy Bone

?

Multiple ChoiceA: OsteonB: Osteonic CanalC: Periosteum D: Spongy Bone

?

Multiple Choice• Identify the Lacunae

A

B

Multiple Choice• Identify the Canaliculi

A

B

Bone Development and Growth

Intramembranous Bones: Flat Bones

o Develop from sheet-like masses of connective tissue that form where future bones will be located

Intramembranous Bone

Endochondral Bone• Long Bones• Develop from masses of hyaline cartilage shaped

like bones.

Long Bone Growth• In the developing body, the

epiphyseal disk separates the diaphysic ossification center and the epiphysic ossification center.

• The epiphyseal disk is a layer of cartilage that allows bones to continue to grow in length.

• When the growth centers meet and the cartilage disappears, the bone can no longer grow in length.

Chapter Project

Homework Questions• How can the epiphysial disk sustain damage?• What happens if this disk is damaged?

Write your answers into your notes. Come to class tomorrow prepared to discuss.

Exit Ticket1. Epiphyseal Disk2. Epiphysic Ossification Center3. Diaphysic Ossification Center

A

B

C

D