LESSON 21 (Bone) Flashcards
What are the 6 function of bones?
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 actions
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
What is bone made out of?
- mostly Bone (OSSEOUS) Connective Tissue
- but bones also have nervous tissue, cartilage, fibrous connective tissue, muscle cells, and epithelial cells in its blood vessels.
In the bone what does the Dense Outer Layer consist of?
Compact bones that look smooth and solid
What is inside the compact bone?
- Spongy bone
- Trabeculae (looks like a honeycomb, needle-like, or flat pieces)
What are the spaces within the spongy bone filled with?
- red bone marrow (which is filled with red blood cells)
OR - yellow bone marrow (which is filled with adipose cells)
What is the diaphysis and what is it made out of?
- A long tubular shaft of bone where it grows in between
- made out of outer layer of compact bone around a central medullary cavity with Yellow Bone Marrow
What is the Epiphyses and what is it made out of?
- the end of long bones which grows over
- consists of compact bone around spongy bone filled with red marrow
What is the Metaphysis?
- the transition between the diaphysis and the epiphysis
- where you can find the epiphyseal line
What is the outside bone covered by?
Periosteum Membrane
What does the Periosteum contain?
- An outer Fibrous Layer of dense irregular connective tissue which secures the membrane to bone matrix
- nerve fivers
- blood vessels
What is the Internal Surface of the bone lined by?
Endosteum
what does the Endosteum cover?
The trabeculae of spongy bone
What layer does the Periosteum and Endosteum each contain?
An Osteogenic layer
- the inner layer is in contact with the bone that contains osteoprogenitor stem cells
What are the 5 major cell types of bone tissue?
1) osteogenic cells (aka osteoprogenitors)
2) osteoBlasts (B= BUILD BONE)
3) osteocytes
4) osteoClasts (C= CARVE BONE)
5) bone-lining cells (Periosteal and Endosteal cells)
What are Osteoprogenitor Cells?
are mitotically active stem cells in Periosteum and Endosteum
What happens when Osteoprogenitor Cells are stimulated?
they differentiate into Osteoblasts or Bone-lining cells
What are osteoblasts?
Bone-forming cells that secrete un- mineralized bone matrix called OSTEIOD
What are Osteoid made up of?
Collagen and calcium-binding proteins
What happens when Osteogenic have fully transformed into Osteoblasts
They can no longer undergo mitosis
What are Osteocytes?
Mature bone cells in lacunae that no longer divide
What are the functions of Osteocytes?
- maintain bone matrix
- act as stress or strain sensor
- sends info to Osteoblasts and Osteoclasts (cells that destroy bone) so bone remodelling can occur
What are Osteoclasts?
- they are derived from the same Hematopoietic stem cells that produce macrophages
- they are large multinucleate cells that break down bone
When active where are Osteoclasts located?
- located in depression called Resorption Bays
What are Bone-lining cells
Flat cells that work with osteocytes that helps maintain bone matrix
Where are Bone-lining cells found?
- On the bone surface where there aren’t any Osteoblasts or Osteoclasts
- not inside the Lacunae
What are EXTERNAL bone lining cells called?
Periosteal cells
What are INTERNAL bone-lining called?
Endosteal Cells
