THE MAKING OF A BONE

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Bone Cells

• Osteoprogenitor cells differentiate into osteoblasts.

1. Osteoprogenitor cells- stem cells of bone.

• Spindle shaped• Oval nucleus• Pale cytoplasm• Found in the

covering of the bone, and lining of inner cavity of bone.

2. Osteoblasts- make the extracellular matrix .

– Osteoblasts differentiate into osteocytes.

• Cells are more columnar

• have well developed Golgi bodies

3. Osteocytes-maintain the matrix.

• Note how osteocytes are connected to each other.

• They live in small spaces in the matrix called lacunae.

4. Osteoclasts- -secrete acid that breaks down mineralized matrix

• Multinucleated

• Large

After bone is broken down, what cell will invade the area and deposit new bone tissue?

Osteoblast

Bone Tissue

Compact bone

Found in the shafts of our long bones and on the inner and outer surface of our flat bones.

Provide strength. Osteon- cylinder shaped unit

Central/Haversion canal- contains blood vessels

Canaliculi- small tubes in the matirx that connect bone cells

Lacuna- Cavity that holds an osteocyte

Lamellae- layers of matrix

1 2

3

4

The Structure of BoneSpongy (cancellous) bone.

• Found within flat bones and in the ends of long bones.

• Stores red bone marrow

How do you think compact and spongy bone got their names?

Cartilage

• Hyaline cartilage

-found at ends of long bones between joints

-important in bone growth, protects ends of bones

• Fibrocartilage-found between vertebrae

-cushions

Dense Connective tissue (regular)

• Covering of a bone• Allows for attachment of tendons and ligaments

Blood

• Found throughout the bone• Brings nutrients, removes wastes

-Nervous tissue

• Found in the covering of the bone• Sends and receives messages

Together these tissues function in...

1. Support and Movement (Explain)– Our bones provide support for sitting and standing.– Our bones act as levers for our muscles to pull

against.

2. Protection (Explain)– Our skulls protect our brain.– Our vertebrae protects our spinal cord.– Our ribcage acts as a shield to protect our important

thoracic organs (heart and lungs).

3. Storage(What is bone storing?)

– Our skeletal tissue stores minerals that can be released as needed- calcium and phosphorous

– Adult long bones store yellow marrow, an energy reserve

4. Hematopoiesis

-formation of blood cells

Types of bones

1. Flat bones• Have broad flat

surfaces (often compared to a plate of armor)

• Protect major internal organs

Types of bones

2. Long Bones• Longer than wide,

growth plates at either end

• Serve as rigid levers that are acted upon by skeletal muscle to produce movements

Types of Bones

3. Short bones• Block-like; length,

width and height are almost equal

• Glide past one another enabling the ankles and wrists to move in multiple directions

Scaphoid- wrist bone

Types of Bones

4. Irregular Bones• Variety of shapes,

many projections, don’t fit into other categories

• Projections allow for muscle attachments, shapes allow for limited motion and protection

Types of bones

5. Sesamoid bone

-small bones embedded within tendons and adjacent to joints

-protect the tendon and improve its mechanical advantage

Lab: Types of Bones

Success in Lab:

1.Find a picture of the bone

(purple star ) in your book,

determine its name and type.

2.Do not move to the next lab station until it is open.

3.Do not experience "lab rage".

4. Always move in a counter-

clockwise direction.

Naming the parts of a long bone.

Preserved cow femur

The membranes of bone.

• Bones are protected by a membrane of dense regular connective tissue.– The superficial

surface is covered with the periosteum.

– The surface of the medullary cavity is covered with the endosteum.

Freshly cut cow femur

Formation, Growth and Repair of Bones

Upload 7.08 Formation, Growth and Repair notes to eBackpack

Osteogenesis: Formation of Your Bones

Compare the two types of bone formation.

The cartilage or membranes are ultimately replaced with bone tissue.

Ossification: The process of forming bone.

Endochondral OssificationEndo=within

Chondral=cartilage

What type of bone is this?

Intramembranous boneIntra=within

What type of bone is this?

Formation begins with….

IntramembranousFlat bones are initially formed of connective tissue membranes .

EndochondralLong bones are initially formed from a cartilage model

Blood supply?

Why?

Results in compact bone?Results in spongy bone?

Growth of Long Bones

Figure 6.8

Study the picture and then finish the notes.

Growth: Enlarging Your Bones• Lengthwise growth of long bones occurs in

cartilage structures called

epiphyseal plates.– Epiphyseal plates are four-layered structures

found between the epiphysis and diaphysis of long bones.

– Epiphyseal plates are converted to bone following puberty, ending our ability to increase in height.

Word bank: diaphysis, epiphyseal plates, epiphysis, puberty

Is this person done growing?How do you know?

Increasing Bone Diameter.• As your bones lengthen, they must also

increase in diameter.– They do this be increasing osteoblast activity

in the periosteum.

• They must also increase the diameter of their medullary cavity.– They do this by increasing osteoclast activity

in the endosteum.

Word Bank: …blast, …clast, …cyte, ….progenitor

Remodeling: Keeping Your Bones New.

• Throughout life, we remodel bones to keep them new.

• Osteoclasts resorb bone matrix to make room for new matrix.

• Osteoprogenitor cells produce new osteoblasts

• Osteoblasts produce new bone matrix.

Word bank: Osteoprogenitor, Osteoblast, Osteocyte, Osteoclasts

RemodelingFigure 6.10

Figure 6.9

Bone Disease: Osteoporosis

Collagen framework and deposited minerals are broken down faster than they are formed normally

The canals that connect the osteocytes become wider weakening the bone

Compare normal bone and osteoporosis.

What happens to the strength of the bone during osteoporosis?

Bone Disease: Sarcoma

• Bone cancer• Osteosarcoma is the

most common and occurs in long bones

• Chondrosarcoma occurs mainly in the pelvis, ribs and sternum

Osteochondroma

• What’s wrong with Curtis?

• Non-cancerous bone growth

Non-cancerous bone tumor

• After removal of a tumor on the femur, a 7 inch incision was made to insert stabilizing hardware.

Bone Disease: Osteomyelitis

• Infection of a bone, usually by bacteria

• Watch Amazing Medical Stories

Bone disease: Osteomalacia

• What do you notice in the X-ray?

• A loss of calcium and phosphorus, often as the result of vitamin D deficiency, can cause weak bones

• Known as rickets

Bone Fractures

• Depends on the direction and degree of force.

• Types

-Simple- bone remains beneath the skin

-Compound- bone projects above skin

What type is this?

Crushed

Twisted

PartialAngular to boneaxis

Right angleto bone axis

What’s wrong with Mitch

Transverse fracture

Ryan Regeth

• What’s wrong?• Broken clavicle

at the acromion process

Zach Janczak

• What’s wrong?• 4th metacarpal

Alyssa Woo

Stress Fracture:

-tiny cracks in a bone

-caused by the repetitive application of force, often by overuse

-common in track athletes

Ms. Cerletty

• What’s wrong?• Patellar ACL

autograft, screw protruding from tibia after 22 years

Michael Mathwick

Before surgery After surgery

What’s wrong?

Note the bloody area on the bone. This is where a piece of the femur is missing.

Allograft from a cadaver

Repaired bone

Bone Repair

• 1 hour

• Several days

• 1-2 weeks

• 2-3 months

A. Soft, spongy bone is deposited on the callus, blood vessels heal and grow across the break

B. New compact bone replaces the callus, completing the repair

C. Blood leaking from the site of injury rapidly forms a clot

D. Fibroblasts form a callus. The callus gradually bridges the gap between the broken bone ends, replacing the clot

Bone Repair

Left wrist ganglion cyst excision

Excision

It’s a beauty!

Bone TerminologyTerms used to describe bone structures

Depressions: Low area or indentation

• Coronoid fossa- elbow joint

Fossa: A relatively deep pit or depression

Cavity/Passageway: a hole or opening

Obturator foramen

Foramen: An opening through a bone- passageway for blood vessels and nerves

Articulation: where 2 bones meet

Coronal suture

Suture: Immovable joint which is visible as a seam on the surface of skull bones.

Projection: A prominence or raised area

Greater tubercle

Lesser tubercle•a small knob-like process

Deltoid tuberosity•knob-like process larger than a tubercle

Lab Directions1. Always move in a counter-clockwise direction.

2. Do not move to a lab station until it is open.

3. Do not experience "lab rage".

4. Find a picture of the bone in your book.

5. Find a definition for the bone structure on page 142.