Lecture 21 - Bone

Question 1

Six functions of bone

Answer 1

1. Support for body and soft organs.
2. Protection of the brain, spinal cord and vital organs.
3. Movement by acting as levers for muscle action.
4. Mineral and growth factor storage for calcium and phosphorus, and growth factors reservoir.
5. Blood cell formation or hematopoiesis occurs in the red bone marrow cavities of certain bones.
6. Triglyceride (fat) storage in yellow bone marrow adipocytes can be used as an energy source.

Question 2

Bone structure

Answer 2

Mostly made of bone (osseous) connective tissue
Also contain nervous tissue, cartilage, fibrous connective tissue, muscle cells and epithelial cells in its blood vessels

All bone has dense outer layer - compact bone

Inside the compact bone is spongy bone which consists of honeycomb, flat pieces called trabeculae

Question 3

Red bone marrow

Answer 3

Full of red blood cells

Question 4

Yellow bone marrow

Answer 4

Full of adipose cells (fat cells)

Question 5

Diaphysis

Answer 5

Shaft of bone
Made of an outer layer of compact bone around centrally medullary cavity filled with yellow bone

Question 6

Epiphysis

Answer 6

End caps
Consist of compact bone around spongy bone filled with red marrow

Question 7

Metaphysis

Answer 7

Transition between diaphysis and epiphysis

Where we find epiphyseal plate (where bone growth occurs)

Question 8

Periosteum membrane

Answer 8

Membrane on outside of bone

Contains outer fibrous layer of dense irregular connective tissue that secure membrane to bone matrix

Contains many nerve fibres and blood vessels that pass into shaft of bone through NUTRIENT FORAMEN openings

Anchoring point for tendons and ligaments

Question 9

Endosteum membrane

Answer 9

Membrane in the internal surface of bone

Delicate connective tissue

Covers trabeculse of spongy bone

Lines canals that pass through compact bone

Contains osteogenic cells that can differentiate into other bone cells

Question 10

Osteogenic layer

Answer 10

Inner layer in contact with bone that contains osteoprogenitor stem cells, that give rise to almost all bone cells

Question 11

Five major cell types in bone tissue

Answer 11

Osteogenic cells (also called osteoprogenitors)

Osteoblasts (osteoBlasts Build bone)

Osteocytes

Osteoclasts (osteoClasts Carve bone)

Bone-lining cells (periosteal and endosteal cells)

Question 12

Osteogenic cells

Answer 12

AKA osteoprogenitor cells

Mitotically active stem cells in periosteum and endosteum

When stimulated,differentiate into osteoblasts or bone lining cells. Some remain Osteogenic stem cells

Question 13

Osteoblasts

Answer 13

Actively mitotic

Bone forming cells, secrete un-mineralized bone matrix called Osteoid

Osteoid made up of collagen and calcium binding proteins

Question 14

Osteocytes

Answer 14

Mature bone cells in lacunae, no longer divide

Maintain bone matrix and act as stress or strain sensors

Send info to osteoblasts and osteoclasts so bone remodelling can occur

Question 15

Osteoclasts

Answer 15

derived from the same hematopoietic stem cells that produce macrophages.

large multinucleate cells that break down bone.

When active, located in depressions called resorption bays.

have ruffled borders that increase surface area for the degradation of bone.

Question 16

Bone lining cells

Answer 16

flat cells that work with osteocytes, help maintain bone matrix. found on bone surfaces in places where there aren’t any osteoblasts or osteoclasts.

resemble osteocytes but aren’t inside lacunae because they are on the edges of the bone structure.

Question 17

Periosteal cells

Answer 17

External bone surface lining cells

Question 18

Endosteal cells

Answer 18

Internal bone surface lining cells