Skeletal System

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Skeletal System

• Chapter 6 7

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htm
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Skeletal System Cartilage

• Skeletal cartilage consists primarily of water.
  (80)
• Cartilage contains no nerves or blood vessels.
• Chondroblasts new cell growth cells
• Chondrocytes mature cells
• Lacunae groups of cavities that contain the
  chondrocytes

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Three types of cartilage
Fibrocartilage Tensile strength with the ability
to absorb compressive shock

• Elastic cartilage
• Maintains shape while allowing great flexibility

• Hyaline Cartilage
• Most abundant

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Skeletal System

• Organization of the skeletal system
• Axial skeleton revolves around the vertical axis
  of the skeleton
• Appendicular skeleton make up the limbs that
  have been appended to the axial skeleton

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Skeleton

• Consists of
• bones
• Cartilage
• Membranes that
• Line the bones.

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• Types of Bones
• 1.Long bones are longer than they are wide.
• 2. Short bones are cubelike, about as long as
  they are wide.
• 3. Flat bones, such as ribs and skull bones, are
  thin or flattened.
• 4. Irregular bones, such as vertebra, facial
  bones, have specific shapes unlike the other
  types of bones.

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Functions of bones

• Support bones provide a framework for the
  attachment of muscles and other tissue
• Protection bones such as the skull and rib cage
  protect internal organs from injury
• Movement bones enable body movements by acting
  as levers and points of attachment for muscles.
• Mineral storage. Bones serve as a reservoir for
  calcium and phosphorus, essential minerals for
  various cellular activities throughout the body.
• Blood cell production the production of blood
  cells (hematopoietic) occurs in the red marrow
  found within the cavities of certain bones.
• Energy storage lipids(fats) stored in adipose
  cells of the yellow marrow serve as an energy
  reservoir

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Bone

• Bone is an organ that includes
• Connective tissue(bone, blood, cartilage,
  adipose, and fibrous connective tissue)
• Nervous tissue
• Muscle and epithelial tissues (within the blood
  vessels)

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Bone Structure Gross Anatomy
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Two types of bone tissue

• Compact bone is the hard material that makes up
  the shaft of long bones and the outside surfaces
  of other bones.

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Two types of bone tissue

• Spongy bone consists of thin, irregularly shaped
  plates called trabeculae, arranged in a
  latticework network.

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Long bone structure

• Location of Hematopoietic tissue in bones
• Red marrow located within cavities of spongy bone
  of long bones and in the diploe of flat bones
• Infants all areas of spongy bone contain red
  blood cells
• Adults in the head of the femur and humerus, flat
  bone of sternum, and irregular bone of the
  pelvis

Epiphyseal line
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Microscopic Structure of Bone
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Chemical Composition of Bone

• Bone consists of organic and inorganic components
• Organic components include the cells
  (osteoblasts, osteocytes, and osteoclasts) and
  Osteoids
• Inorganic components include hydroxyapatites
  (mineral salts) largely calcium phosphates

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Organic bone cells

• Osteoblasts - bone-forming cells
• Osteocytes - mature bone cells
• Osteoclasts - large cells that resorb or break
  down bone matrix
• Osteoid - unmineralized bone matrix composed of
  proteoglycans, glycoproteins, and collagen

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Bone Markings

• The external surface of bones are rarely smooth
  and featureless.
• These marking are named in many different was.
• http//www.studystack.com/menu-210122

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Bone Development

• Osteogenesis and ossification are synonyms
  indicating the process of bone tissue formation
• Occurs when?
• Embryos leads to formation of the bony skeleton
• Bone growth until early adulthood to increase
  in size (bones are capable of growing in
  thickness throughout life.)
• Ossification in adults serves mainly for
  remodeling and repair of bones

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Formation of the Bony Skeleton

• Begins at week 8 of embryo development
• 1.Intramembranous ossification bones develops
  from a fibrous membrane
• Formation of most flat bones of the skull and the
  clavicles
• 2.Endochondral Ossification bone formation that
  occurs by replacing hyaline cartilage
• Begins in the second month of development
• Uses hyaline cartilage bones as models for bone
  construction
• Requires breakdown of hyaline cartilage prior to
  ossification

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Postnatal Bone GrowthBone Growth in length

• 1. Epiphyseal plate or cartilage growth plate
• cartilage cells are produced by mitosis on
  epiphyseal side of plate
• cartilage cells are destroyed and replaced by
  bone on diaphyseal side of plate
• Between ages 18 to 25, epiphyseal plates close.
• cartilage cells stop dividing and bone replaces
  the cartilage (epiphyseal line)
• Growth in length stops at age 25

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Growth in length of long bones
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Hormonal Regulation of bone growth during youth

• Initially promote adolescent growth spurts
• Cause masculinization and feminization of
  specific parts of the skeleton
• Later induce epiphyseal plate closure, ending
  longitudinal bone growth

• Initially promote adolescent growth spurts
• Cause masculinization and feminization of
  specific parts of the skeleton
• Later induce epiphyseal plate closure, ending
  longitudinal bone growth

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Bone Remodeling

• In adult skeletons, bone remodeling is balanced
  bone deposit and removal, bone deposit occurs at
  a greater rate when bone is injured, and bone
  resorption allows minerals of degraded bone
  matrix to move into the blood.

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Control of Remodeling

• The hormonal mechanism is mostly used to maintain
  blood calcium homeostasis, and balances activity
  of parathyroid hormone and calcitonin.
• Nutrition - Ca, P, Mg, vitamins, A, C and D.
• In response to mechanical stress and gravity,
  bone grows or remodels in ways that allow it to
  withstand the stresses it experiences

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Calcium

• The human body contains some 1200-1400 g of
  calcium
• Over 99 of which is present as bone minerals
• Normal range is narrow 9-11 mg per 100ml of
  blood by the hormonal control loop
• Calcium is absorbed from the intestine under the
  control of vit. D metabolism
• Daily req birth to 10yrs 400-800 mg 11 to 24
  yrs 1200-1500 mg

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Wolff's law - a bone grows or remodels in
response to the forces or demands placed upon it
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Comparing Skeletons

• Adult 206
• Child 275
• Adult Higher of yellow marrow and lower of
  red marrow(sternum, pelvis, femur)
• Child Higher of red marrow and lower of
  yellow marrow
• Adult higher of bone and lower of cartilage
• Child higher of cartilage and lower of bone

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Fractures
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Stages in the healing of a bone fracture
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Homeostatic imbalances of Bone

• 1. Osteomalacia
• 2. Rickets
• 3. Osteoporosis
• 4. Pagets disease
• 5. achondroplasia
• 6. bony spur
• 7. ostealgia

• 8. osteitis
• 9. osteomyelitis
• 10. osteosarcoma
• 11. Pathologic fracture
• 12. traction

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Osteomalacia and Rickets
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osteoporosis
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Pagets disease
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achondroplasia
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Bony spur
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osteitis
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osteomyelitis
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osteosarcoma
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Joints (articulations) site where two or more
bones meet

• Function to give the body mobility and to hold
  bones together
• Joints are the weakest parts of the skeleton
• Functional Classification
• Synarthroses immovable joints
• Amphiarthroses movable joints
• Diarthroses freely moveable joints

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Classifying joints based on structure (PAGE 251)

• Fibrous Sutures

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• Cartilaginous

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Synovial joint (page259-260)

• Plane
• Hinge
• Pivot
• Condyloid
• Pivot
• Saddle
• Ball and socket

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Diseases of the bone and/or skeletal sys.

• 5 conditions and/or diseases
• Symptoms
• Causes
• Treatments
• http//training.seer.cancer.gov/module_anatomy/uni
  t3_4_bone_classification.html