Chapter 7 Skeletal System. HW-None 1. Take out 7.1-7.3 notes. 2. Do not get your models yet!

Chapter 7 Skeletal System

HW-None

1. Take out 7.1-7.3 notes.

2. Do not get your models yet!

Skeletal system functions:-muscle attachment-protection-support-blood cell production

– Hematopoiesis-red bone marrow producing blood cells

-storage of minerals

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Types of bones• Flat-cranium, ribs, scapula, sternum• Short-cube shape, wrist and ankle• Long-thigh, forearms, toes• Irregular-vertebrae• Sutural bones-Wormian bones

– Location classification– Between joints of certain cranial bones

• Sesamoid bones-small bones in tendons (patella, 2 hand, 1 foot)

Parts of a Long Bone 1. epiphysis-wide end of a bone

2. Hyaline cartilage-covers the epiphysis.

3. Diaphysis-shaft of bone (long part)

4. Metaphysis-epiphyseal plate area

5. periosteum-covers bone-attach to ligaments and tendons-nutrition and growth-made of vascular

connective tissue (help with repair & formation)

y.

Medullary or Marrow cavity

• Space with fatty yellow bone marrow in adults

• Endosteum-inner lining of the medullary canal

MORE TO COME!!

• Go to page 127 in the book to help label the picture.

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Two types of bone tissue• Spongy bone

– Cancellus bone

– Does not contain osteons (segments of bone)

– Contains thin plates called trabeculae

– Spaces between bones are filled with red marrow

– Plates have osteocytes

– Found in short, flat, and irregular bones

-ends of long bones

-can handle compression

• Compact Bone-dense bone

– Shaft of bone; bear weight

http://www.youtube.com/watch?v=ylmanEGjRuY

Microscopic Structure of Long Bones-BONE HAS TONS OF MATRIX (lamallae)

*matrix made of collagen (strength) and inorganic salts (calcium phosphate) make it hard and resist crushing-OSTEONS-segment of bone

-put tons of osteons together=boneconnected by Volkman’s canals

.

1 osteon has several parts*central canal (Haversian canal) filled with nerves

*perforating canals (Volkmann’s canals)-connect central canals of blood vessels to periosteum; run perpendicular to haversian canal)

* osteocytes-bone cells

-lacunae-residence of osteocytes or chamber-canaliculi-canals that connect lacunae or osteocytes; passageway for substance and key to communication

http://www.youtube.com/watch?v=ZNZOAM9QGyI

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Bone OssificationA. Bones form by replacing connective tissue (hyaline

cartilage) in the fetus.B. 2 types:

-intramembranous bones-form sheetlike layers of connective tissue

-example: flat bones of skull-osteoblasts are active forming osteocytes (these are mature bone cells)

-endochondral bones-cartilage masses form -eventually hyaline cartilage is replaced by bone-most common

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Video 1http://www.sophia.org/packets/bone-development-

endochondral-ossification

You tube videohttp://www.youtube.com/watch?

v=x0TASU2LNa0&feature=related Endochondral Bones 1.They first develop as hyaline cartilage

models and are then replaced with bone.-replace from the outside first

2. Cartilage is broken down in the diaphysis (middle of the bone)

and progressively replaced with bone while the periosteum (outside of bone) develops on the outside.

3. Cartilage tissue is invaded by blood vessels and osteoblasts (from

periosteum) -form spongy bone from

middle to outside-primary ossification

center

4. Osteoblasts beneath the periosteum lay down compact bone outside the

spongy bone. 5. Secondary ossification centers appear

later in the epiphyses.

6. A band of hyaline cartilage, the epiphyseal plate(growth plate), forms between the two ossification centers.

-shaft and ends are the ossification centers

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7. Osteoclasts break down the matrix and are replaced with bone-building osteoblasts that deposit bone in place of calcified cartilage.8. Epiphyseal plates are responsible for lengthening bones while increases in thickness are due to intramembranous ossification underneath the periosteum.

http://www.youtube.com/watch?v=X6E5Rz9tOKE

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CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Homeostasis of Bone Tissue 1. Osteoclasts tear down and osteoblasts build bone throughout the lifespan, with an average of 3% to 5% of bone calcium exchanged annually.

*Bone cancers have overactive osteoclasts.

*Prostate cancer that has moved to the bone marrow can have the opposite effect (osteoblasts are creating)

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