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Bone Tissue

Aspects of the bone tissue includes:

  1. It's a Dynamic tissue that continually remodels itself
  2. Its a grouping of connective tissue with a matrix hardened by minerals
  3. Bones make up the skeletal system


Functions of the skeletal system

Functions of the skeletal system includes:

  1. Supports the body.

  2. Facilitates movement.

  3. Protects internal organs.

  4. Produces blood cells.

  5. Stores and releases minerals and fat.

  6. Buffers blood against excessive pH changes


Structure of Long bones

Long Bones Structures includes: 

  1. Epiphysis (ends), they are Distal and Proximial 

  2. Diaphysis (shaft)

  3. Medullary (bone marrow) cavity


Articular Cartilage ​

Hyaline cartilage covers the surface of joints the Epiphysis (distal and proximal Epiphysis) allowing for articulation of bones.


Long bones

Long Bones are: 

  1. Longer than wide

  2. Rigid levers acted upon by muscles

  3. Assist in creating our Limbs


Short bones

Short bones are:

  1. Articuluation of Joints

  2. Equal in length and width

  3. Glide across one another in multiple directions

  4. Designed for strength and compactness


Flat bones

Flat bones are:

  1. Assist in Articulations
  2. Protect soft organs
  3. Curved but wide & thin


Irregular bones

Irregular bones are:

  1. Elaborate shapes that don’t fit into the other categories
  2. This includes the Sphenoid bone (bones of bones)


Bone Cell Types

There are (4) four Bone Cell types:

  1. Osteoprogenitor
  2. Osteoblasts
  3. Osteocytes 
  4. Osteoclasts 


Osteoprogenitor Cells

is a specialized cell that could dividing into two stem cells. They could become any type of bone cells.


Osteoblasts Cells

Osteo-Blasts (building of bones)

  1. Osteoblasts are the younger cells
  2. are the structural cells that form new bone.
  3. They also come from the bone marrow and secrete collagen


Osteocytes Cells

  1. They come from osteoblasts.
  2. Some of the osteoblasts turn into osteocytes while the new bone is being formed.
  3. These cells can sense pressures or cracks in the bone and help to direct where osteoclasts will dissolve the bone.


Osteoclasts Cells

  1. Osteoclasts are older cells that are broken down
  2. are large cells that dissolve / breakdown / reabsorb the bone.
  3. They come from the bone marrow and are related to white blood cells. 


Bone Matrix Composition

25% water

25% protein fibers

50% minerals


Bone Matrix Contains

Bone Matrix contains some:

  1. Calcium carbonate, calcium phosphate
  2. but mostly hydroxyapatite, which is the PRIMARY salt that makes bone hard.



is the PRIMARY mineral of salt that form calcium making bone hard 


Bone Matrix Deposited Where

Matrix is deposited in a framework of collagen fibers, calcification (calcium and salts) or mineralization

  1. Salts confer hardness on bone
  2. Collagen fibers give bones Tensile strength (being able to bend a little without breaking)



  1. Bone are made up of several different tissues (connective) working together:
  • Bone
  • Cartilage
  • Dense connective tissue
  • Epithelium
  • Various blood forming tissues
  • Adipose tissue
  • Nervous tissue.
  1. Each individual bone is an organ; the bones, along with their cartilage, make up the skeletal system.


Bone Type

There are (4) Four types of bones:

  1. Long bones

  2. Short bones

  3. Flat bones

  4. Irregular bones


Type of Bones

Bone may be categorized as compact or spongy



Osteons are cylindrical structures that contain a mineral matrix and living osteocytes connected by canaliculi, which transport blood.



The Lamella is a Cylinders of tissue area of Matrix that sits between the rings of the Osteocytes.


Compact Bone

Dense bone tissue consists of osteons, know as the Haversian systems = the basic structural unit (STEPS):

  1. Lamellae - Cylinders of tissue formed from layers

  2. Central Canal / Haversian- Contains, Vains, Artiery, Nerves (VAN).  

  3. Osteocytes connected to each other and by tiny canals called  "canaliculi"


Spongy Bone

  1. is made up of Trabeculae which is what gives sponge like appearance  – the spaces is filled with red bone marrow.
  2. Provides strength with little weight for bone structure. 
  3. Spongy bone have few osteons
  4. Blood Vessels go through spongy bones real easy, so it doesn't need a haversian systems.


 Intramembranous Ossification

  1. Intramembranous ossification directly converts the mesenchymal tissue to bone and forms the flat bones of the skull, clavicle, and most of the cranial bones.

  2. Intramembranous ossification does not not go through Cartilage.


Endochondrial Ossification

Endochondral ossification begins with mesenchymal tissue transforming into a cartilage, the growing cartilage is replaced by bone to form the growing skeleton.

  1. is involved in:
    1. embryonic bone formation
    2. growth in length of long bones
    3. and fracture healing


Bone Formation Steps

Most bone is formed by Endochondral Ossification or osteogenesis (Inside then outward):

  1. Step 1 = Cartilage forms

  2. Step 2 = Cartilage grows

  3. Step 3 = Bone replaces the cartilage from the inside center outward.


Bone Mineral Resorption

  1. Bone is the major reservoir for calcium (Ca++)
  2. If blood levels get to low, the body will pull from the bones

  3. Blood level of calcium ions is very important in cardiac, nerve, enzyme, blood


Human Growth Hormone

Human Growth Hormone (GH) stimulate bone deposition, in addition to thyroid hormone, parathyroid hormone, and calcitonin


Thyroid Hormone

  1. Thyroid Hormone - promotes growth and maturity
  2. Calcitonin aka thyroid gland - promotes bone formation, inhibits osteoclast activity.