LESSON 21 (Bone)

Question 1

What are the 6 function of bones?

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 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

Question 2

What is bone made out of?

Answer 2

• mostly Bone (OSSEOUS) Connective Tissue
• but bones also have nervous tissue, cartilage, fibrous connective tissue, muscle cells, and epithelial cells in its blood vessels.

Question 3

In the bone what does the Dense Outer Layer consist of?

Answer 3

Compact bones that look smooth and solid

Question 4

What is inside the compact bone?

Answer 4

• Spongy bone
• Trabeculae (looks like a honeycomb, needle-like, or flat pieces)

Question 5

What are the spaces within the spongy bone filled with?

Answer 5

• red bone marrow (which is filled with red blood cells)
  OR
• yellow bone marrow (which is filled with adipose cells)

Question 6

What is the diaphysis and what is it made out of?

Answer 6

• 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

Question 7

What is the Epiphyses and what is it made out of?

Answer 7

• the end of long bones which grows over
• consists of compact bone around spongy bone filled with red marrow

Question 8

What is the Metaphysis?

Answer 8

• the transition between the diaphysis and the epiphysis
• where you can find the epiphyseal line

Question 9

What is the outside bone covered by?

Answer 9

Periosteum Membrane

Question 10

What does the Periosteum contain?

Answer 10

• An outer Fibrous Layer of dense irregular connective tissue which secures the membrane to bone matrix
• nerve fivers
• blood vessels

Question 11

What is the Internal Surface of the bone lined by?

Answer 11

Endosteum

Question 12

what does the Endosteum cover?

Answer 12

The trabeculae of spongy bone

Question 13

What layer does the Periosteum and Endosteum each contain?

Answer 13

An Osteogenic layer
- the inner layer is in contact with the bone that contains osteoprogenitor stem cells

Question 14

What are the 5 major cell types of bone tissue?

Answer 14

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)

Question 15

What are Osteoprogenitor Cells?

Answer 15

are mitotically active stem cells in Periosteum and Endosteum

Question 16

What happens when Osteoprogenitor Cells are stimulated?

Answer 16

they differentiate into Osteoblasts or Bone-lining cells

Question 17

What are osteoblasts?

Answer 17

Bone-forming cells that secrete un- mineralized bone matrix called OSTEIOD

Question 18

What are Osteoid made up of?

Answer 18

Collagen and calcium-binding proteins

Question 19

What happens when Osteogenic have fully transformed into Osteoblasts

Answer 19

They can no longer undergo mitosis

Question 20

What are Osteocytes?

Answer 20

Mature bone cells in lacunae that no longer divide

Question 21

What are the functions of Osteocytes?

Answer 21

• maintain bone matrix
• act as stress or strain sensor
• sends info to Osteoblasts and Osteoclasts (cells that destroy bone) so bone remodelling can occur

Question 22

What are Osteoclasts?

Answer 22

• they are derived from the same Hematopoietic stem cells that produce macrophages
• they are large multinucleate cells that break down bone

Question 23

When active where are Osteoclasts located?

Answer 23

• located in depression called Resorption Bays

Question 24

What are Bone-lining cells

Answer 24

Flat cells that work with osteocytes that helps maintain bone matrix

Question 25

Where are Bone-lining cells found?

Answer 25

• On the bone surface where there aren’t any Osteoblasts or Osteoclasts
• not inside the Lacunae

Question 26

What are EXTERNAL bone lining cells called?

Answer 26

Periosteal cells

Question 27

What are INTERNAL bone-lining called?

Answer 27

Endosteal Cells