Skeletal System: Tissue and physiology

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Chapter 7 Notes

• Skeletal System Tissue and physiology
• Skeletal tissue is the most distinctive form of
  connective tissue.

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Functions of Skeletal Tissue

• Support
• Ex. Arch of foot, vertebral column, etc.
• Protection
• Ex. Skull protects the brain, rib cage protects
  lungs and heart.
• Movement
• Occurs with the help of joints - act as levers
• Muscle contraction pulls on bones movement

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Functions of Skeletal Tissue

• Mineral reservoir
• Calcium
• Homeostasis of blood calcium levels
• Hemopoiesis - blood cell formation
• Occurs in red bone marrow
• chest
• spinal column in adults
• base of skull
• upper arm and thigh
• In infants or child, all bone marrow is red.

ADULTS
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• Bone Shapes
• Long bone - consists of 6 parts.
• Ex. femur, humerus
• Short bone - ex. Carpals fingers and toes
• Flat Bone scapula back (shoulder blade)
• Irregular bone - vertebrae

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Structure of Long Bone

• Diaphysis
• Main shaft
• Strong support
• Hollow decrease in weight

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Structure of Long Bone

• Epiphysis
• Ends of long bone
• Bulbous shape allows for muscle attachment and
  gives stability to joints
• Contains spongy tissue
• contains marrow - red or yellow

Spongy bone
Compact bone
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Structure of Long Bone

• Articular cartilage
• Covers joint surface of epiphysis
• Cushions jars and blows

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Structure of Long Bone

• Periosteum
• Dense fiberous membrane
• Covers bone except at joints
• Tedons interlace with and anchor muscles
• Contain many blood vessels (connects with
  haversian canal)
• Osteoblasts (bone forming cells) compose inner
  layer

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Structure of Long Bone

• Medullary Canal
• Tube of diaphysis
• Contains marrow
• Endosteum
• Membrane
• Lines medullary cavity of long bone

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Long Bone Anatomy
http//kidshealth.org/misc/movie/bodybasics/bone.h
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Haversian System

• Identifies microscopic structure of compact bone
  in the diaphysis

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Haversian System Structure

• Lamellae (Lah-Mel-e)
• cylinder shaped layers of calcified matrix
  (non-living)
• Lacunae (la-Kew-nah)
• small spaces
• contains tissue fluid where bone cells
  (osteocytes) live
• imprisoned between lamellae

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Haversian System Structure

• Canaliculi
• (Ka-NALi-ku-li)
• ultra small canals
• radiates out from lacunae to connect each other
• connects also to haversian canal
• Haversian canal
• Contains blood vessels and lymphatic tissue
• Gives nutrients to lacunae through canaliculi
• Gives nutrients to osteocytes

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Haversian System
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Bone Development and Growth

• Osteogenesis - the process of bone formation
• At 12 weeks the skeleton has formed-made of
  cartilage and fibrous tissue.

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Bone Development and Growth

• Fontanels - "soft spots" of an infant's skull

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Osteogensis

• Intramembranous Development
• Prebone structure of skull and mandible
• Takes place within connective tissue
• Connective tissue enlarges to form osteoblasts -
  bone forming cells.
• Bone matrix is formed
• Matrix is calcified by deposits of calcium and
  salts.
• Flat bones grow by adding to their outside
  borders.

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Osteogensis Continued

• Endochondral (all other bones)
• Begin as cartilage
• Cartilage develops periosteum - enlarges into a
  ring
• Cartilage calcifies
• Ossification, hardening of bone, progresses
  toward each epiphysis. (involves addition of Ca
  and Phosphorous ions)
• During bone growth, ephiphyseal cartilage remains
  between ends and shaft growth plate.

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Osteogensis Continued

• Major stages (a-d fetal, e child, f adult) in the
  development of the endochondral bone.

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Bone Growth

• Diameter
• Osteoclasts - enlarge diameter of medullary
  cavity by eating away wall.
• Osteoblasts - build new bone at periosteum
• Occurs throughout life

http//www.personal.psu.edu/staff/m/b/mbt102/bisci
4online/bone/bone5.htm
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Bone Growth Continued

• Childhood
• Bone ossification is greater than bone resorption
  (decomposition) taller
• Adulthood
• Bone ossification and resorption equal one
  another.
• At 35-40, bone ossification decreases and
  resorption is greater.
• Become hollow
• Vertebrae collapse height decrease
• Brittle bones death

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Bone Growth
http//www.pennmedicine.org/encyclopedia/em_Displa
yAnimation.aspx?gcid000112ptid17
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Bone marrow aspiration, direct removal of a small
amount (about 15 millilitres) of bone marrow by
suction through a hollow needle.
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Bone Fracture
http//www.muschealth.com/video/Default.aspx?video
Id10226cId2typerel

• Bone Fracture - break in continuity of bone.
• Types
• Simple - skin remains unbroken
• Compound - broken ends protrude through skin
• Easily infected - osteomyelitis

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Bone Fractures Continued

• A complete fracture is when the bone has broken
  into two pieces.
• A greenstick fracture is when the bone cracks on
  one side only, not all the way through.
• A single fracture is when the bone is broken in
  one place.
• A comminuted (say kah-muh-noot-ed) fracture is
  when the bone is broken into more than two pieces
  or crushed.
• A bowing fracture, which only happens in kids, is
  when the bone bends but doesn't break
• An open fracture is when the bone is sticking
  through the skin.

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Bone Fractures Continued
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Bone Fractures Continued

• Repair - fracture healing
• Damage to blood vessels begins repair sequence.
• Dead bone is removed by osteoclasts-resorption.
• Osteoclasts used as framework for repair tissue
  called callus.
• Callus tissue bonds broken ends of bone outside.
• Callus tissue binds medullary cavity.
• Callus tissue is molded and replaced with bone.
• Electrically induced osteogenesis - uses
  electrical stimuli to heal fractures.

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Bone Fractures Continued

• Major steps in the repair of a fracture.

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Osteoporosis

• Loss of calcified matrix callogenous fibers.
• Occurs most frequently in elderly, white females.
• Decrease levels of estrogen and testosterone.
• Decreased osteoblast activity
• Decreased maintenance of existing bone
• Bone Degeneration
• Spontaneous fractures
• Curvature of the spine
• Treatment
• Estrogen therapy - after menopause
• Dietary supplement of calcium and vitamin D.

http//highered.mcgraw-hill.com/sites/0072495855/s
tudent_view0/chapter6/animation__osteoporosis.html
http//www.muschealth.com/video/Default.aspx?cId
2
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Cartilage

• Cartilage - connective tissue
• Types
• Hyaline
• Elastic Cartilage
• Fibrocartilage

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Hyaline

• Most abundant
• Semi-transparent-bluish, opalescent
• Covers articular surface of bone
• Forms ends of ribs that join to sternum
• Forms rings in trachea, bronchi of lungs, nose

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Elastic Cartilage

• Elasticity and firmness
• Fibers form to external ear, epiglottis, tubes in
  ear, nasal cavity
• Yellowish in color

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Fibrocartilage

• Greatest tensile strength
• Intervertebral disks, point of attachment of some
  large tendons to bones.

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Structure of Cartilage

• Chondrocytes - cartilage cells.
• Avascular - contain no blood vessels.
• Receive oxygen and nutrients through diffusion.
• Increase of collagenous fibers and matrix
  embedded in a gel (not calcified).

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Function of Cartilage

• Shock absorption
• Resists collapse of passageways
• Allows bone growth