Objective 4: Types of bone cells

Osteoblast and Osteocytes are both from

bone cell lineage

Osteoid is made up of

collagen and calcium-binding proteins

Osteoclast cells are from

white blood cell lineage

Collagen makes up ___% of protein and Calcium-binding proteins make up ___%

90;10

Osteogenic cells

-also called osteoprogenitor cells -mitotically active stem cells in periosteum and endosteum -When stimulated, they differentiate into osteoblasts or bone-lining cells -some remain as these kind of stem cells

Osteoclasts

-derived from same hematopoietic stem cells that become macrophages -giant, multinucleate cells function in bone resorption (breakdown of bone)

Osteocytes

-mature bone cells in lacunae that no longer divide -maintain bone matrix and act as stress or strain sensors -respond to mechanical stimuli such as increased force on bone or weightlessness -communicate information to osteoblasts and osteoclasts (cells that destroy bone) so bone remodeling can occur

Osteoblasts

-Bone-forming cells that secrete unmineralized bone matrix called osteoid - Osteoblasts are actively mitotic (undergoing mitosis)

Bone-lining cells

-Flat cells on bone surfaces believed to also help maintain matrix (along with osteocytes) -on external bone surface, these cells are called periosteal cells -on internal surfaces, they are called endosteal cells

Osteoclasts pt2

-When active, cells are located in depressions called resorption bays (SORT of like lacunae for osteocytes) -Cells have ruffled borders that serve to increase surface area for enzyme degradation of bone -also helps seal off area from surrounding matrix

What are the five major types of cells of bone tissue?

1. Osteogenic cells 2. Osteoblasts 3. Osteocytes 4. Bone-lining cells 5. Osteoclasts

Osteoblasts mature into

Osteocytes

Some osteoprogenitor cells become

osteoblast