Ch5 -Skeletal

Question 1

Skeletal System Includes

Answer 1

1 - Osseous tissue 
2 - Ligaments (not tendons) 
3 - Cartilage 
4 - Supportive Connective Tissues

Question 2

Number of Bones

Answer 2

206

Adolescents have more due to growth plates

Question 3

Skeletal

Basic facts

Answer 3

• System of levers for muscles to work 
• 20% of body mass is skeletal (∆ w/age, exercise, pathophysiology) 
• Placed into 6-broad categories based on their shape

Question 4

Bone as Tissue

Answer 4

1 - Dynamic tissue that continually remodels itself
2 - Bones and bone tissue
–bone or osseous tissue is a connective tissue with a matrix hardened by minerals
- individual bones are made up of bone tissue, marrow, cartilage & periosteum
3 – bones make up the skeletal system

Question 5

5 Functions of Skeleton

Answer 5

1 - Support
2 - Protection
3 - Movement
4 - Mineral/Organic Storage
5 - Blood Cell Productions

Question 6

Functions of Skeleton

1 - Support

Answer 6

• Provides structural support of body

- Framework for soft tissues to adhere to

Question 7

Functions of Skeleton

2 - Protection

Answer 7

• soft tissues and organs surrounded by bones

•skull, vertebrae, ribs, pelvis

Question 8

Functions of Skeleton

3 - Movement

Answer 8

• many function as levers for muscles
  •change magnitude of force, direction of muscle pull
  •allows for movement, which can be extremely precise (dexterity of hands).

Question 9

Functions of Skeleton

4 - Mineral / Organics Storage

Answer 9

• calcium and phosphate storage •remodeling: 10-30% of adult skeleton is replaced/year; (100% of infant)
  •very tight regulation of ionized calcium •fat storage (yellow marrow).

Question 10

Functions of Skeleton

5 - Blood Cell Production

Answer 10

• red blood cells (RBC’s)
  • white blood cells (WBC’s)
  • soluble plasma components (clotting factors).
  NOTE: In Marrow Cavity

Question 11

Bone Classification

4 Types

Answer 11

1 - Long Bone
2 -  Short Bone
3 - Flat Bone
4 - Irregular Bones
NOTE:  Broadly catagorized based on shape

Question 12

Structure of Flat Bone

Answer 12

• External and internal surfaces of flat bone are composed of compact bone
  •Middle layer is spongy bone (diploe). No marrow cavity
  •Blow to the skull may fracture outer layer and crush diploe, but not harm inner compact bone

Question 13

Anatomy of Long Bone

Answer 13

• Diaphysis = shaft
  •Epiphysis = one end of a long bone •Metaphysis = growth plate region
  •Articular cartilage over joint surfaces acts as friction & shock absorber
  •Medullary cavity = marrow cavity
  •Endosteum = lining of marrow cavity •Periosteum = tough membrane covering bone but not the cartilage
  –fibrous layer = dense irregular CT
  –osteogenic layer = bone cells & blood
  vessels that nourish or help with repairs.

Question 14

General Features of Long Bones

Answer 14

• Shaft (diaphysis) is cylinder of compact bone containing marrow cavity (medullary cavity) & lined with endosteum (layer of osteogenic cells and reticular connective tissue)
• Enlarged ends (epiphyses) are spongy bone covered with a layer of compact bone enlarged to strengthen joint & provide for attachment of tendons and ligaments 
• Joint surface covered with articular cartilage (cushions and protects articulating bones) 
• Remainder of bone covered with periosteum  - outer fibrous layer of collagen fibers continuous with tendons or perforating (Sharpey’s) fibers that penetrate into bone matrix 
  - inner osteogenic layer important for growth & healing 
• Epiphyseal plate or line depends on age

Question 15

Surface of Bones

Answer 15

• Bone responds to mechanical stress 
• Ridges (eminence, process, tubercle, tuberosity) 
  - tendon insertions 
  - ligament insertions 
• Depressions/ Grooves 
  - blood vessels 
  - nerves 
  - articulations

Question 16

Cells of Osseous Tissue
(How Bones Regenerate)
3 Types

Answer 16

1 - Osteogenic Cells
2 - Osteoblasts
3 - Osteocytes

Question 17

1 - Osteogenic Cells

3 points about them

Answer 17

1 - Reside in endosteum, periosteum or central canals
2 - Arise from embryonic fibroblasts and become only source for new osteoblasts
3 - Multiply continuously & differentiate into osteoblasts in response to stress or fractures

Question 18

2 - Osteoblasts

Answer 18

Form and help mineralize organic matter of matrix

Question 19

3 - Osteocytes

Answer 19

• Are osteoblasts that have become trapped in the matrix they formed
  –cells in lacunae connected by gap junctions inside canaliculi
  –signal osteoclasts & osteoblasts about mechanical stresses

Question 20

Cells of Osseous Tissue

Answer 20

• Osteoclasts develop in bone marrow by the fusion of 3-50 of the same stem cells that give rise to monocytes found in blood
  • Reside in pits called resorption bays that they have eaten into the surface of the bone
  • Osteolysis = acids and enzymes

Question 21

Bone Matrix

Composition of

Answer 21

• • Organic matter 
• dry weight is 1/3 organic protein component collagen, glycosaminoglycans, proteoglycans & glycoproteins 
• • Inorganic matter 
• dry weight is 2/3 inorganic matter 
• calcium salts 
• 85% hydroxyapatite (crystallized calcium phosphate salt) 
• 10% calcium carbonate 
• Other minerals (fluoride, sulfate, potassium, magnesium) 
• • Combination provides for strength & resilience 
• minerals resist compression; collagen resists tension 
• fiberglass = glass fibers embedded in a polymer 
• bone adapts to tension and compression by varying proportions of minerals and collagen fibers.

Question 22

Compact Bone (cortical bone)

Answer 22

• • Osteon (aka: Haversian system) 
  • cylinders of tissue formed from layers (lamellae) of matrix arranged around central canal holding a blood vessel 
    - collagen fibers alternate between right- and left-handed helices from lamella to lamella 
    
    • osteocytes connected to each other and their blood supply by tiny cell processes in canaliculi 
• • Perforating canals (aka: Volkmann canals)  - vascular canals perpendicularly joining central canals
• • Circumferential or outer lamellae