Chapter 7
Skeletal System
HW-None
1. Take out 7.1-7.3 notes.
2. Do not get your models
yet!
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Skeletal system functions:
-muscle attachment
-protection
-support
-blood cell production
– Hematopoiesis-red bone marrow producing blood
cells
-storage of minerals
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=bone
connected 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=ZNZOAM9QG
yI
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Bone Ossification
A. 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
Video 1
http://www.sophia.org/packets/bonedevelopment-endochondral-ossification
You tube video
http://www.youtube.com/watch?v=x0TASU2L
Na0&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
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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=X6E5Rz9tO
KE
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
CopyrightThe 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)