Intro to Skeleton

Question 1

Function of the Skeleton

Answer 1

1. Support of soft tissues of the body
2. Mineral Reservoir (calcium/phosphate)
3. Energy Storage (yellow marrow)
4. Blood Cell Production (red marrow)
5. Protection of Vital Organs
6. Leverage & Movement

Question 2

How much of the body’s calcium is in bones?

Answer 2

98%

Question 3

Where is fat stored in the bones?

Answer 3

medullary cavity of long bones

Question 4

Where is red bone marrow in the bones?

Answer 4

In cavities of spongy bone

Question 5

Connective Tissue of the Skeletal System

Answer 5

1. Connective Tissue Proper
   
   1. Dense Regular CT
      
      1. ligaments, bone sheaths, tendons
   2. Adipose
      
      1. stored in bone
2. Supporting Connective Tissue
   
   1. Cartilage
      
      1. joint discs, invertebral discs, symphysis pubis
   2. Osseous Tissue
3. Fluid Connective Tissue
   
   1. Blood
      
      1. formed in red bone marrow

Question 6

differentiate/change into any connective tissue

Answer 6

Mesenchyme (embryonic CT)

Question 7

Cartilage Characteristics

Answer 7

1. No blood vessels/nerves
2. Consists primarily of water (60-80%)
3. Surrounded by perichondrium
4. Growth ends at 18-20 years
5. Little healing in adulthood
6. Collagen resists tension
7. Poor at resisting “shearing forces”
8. Cartilage cells:
   
   1. chondroblasts
   2. chondrocytes

Question 8

Cartilage Types

Answer 8

1. Hyaline Cartilage
2. Elastic Cartilage
3. Fibrocartilage

Question 9

Hyaline Cartilage Characteristics

Answer 9

1. Most abundant
2. Has fibers (too small to see)
3. Found in young bone
4. Resists compression, but not tolerant of twisting or shearing forces
5. Located on end of bone, growth plate, septum, costal cartilages, developing bone

Question 10

Elastic Cartilage Characteristics

Answer 10

1. Many elastic fibers
2. Tolerates repeated bending, recoil
3. Located within ears and epiglottis

Question 11

Fibrocartilage Characteristics

Answer 11

1. Abundant collagen fibers
2. Resists twisting and compression
3. No perichondrium
4. Located in invertebral disc, menisci, some ligament & tendon attachment to bone

Question 12

Every bone has…

Answer 12

1. Blood vessels, nerves, and lymphatic vessels
2. Two types of osseous tissue

Question 13

Spongy (Cancellous) Bone Characteristics

Answer 13

1. Honeycomb-like netowrk of bone
2. Form trabeculae (beams) to resist directional stresses
3. Cavities filled with red bone marrow
4. Found in epiphysis & center of bone organ
5. Replaced every 4 years

Question 14

What surrounds the trabeculae?

Answer 14

Endosteum

Question 15

Compact Bone Characteristics

Answer 15

1. Bone forms concentric rings of matrix (osteon)
2. Bone cells are trapped within cavities (lacunae)
3. Organized “nested rings” in periphery bone
4. Replaced every 10 years

Question 16

TRUE/FALSE

Depending on body signals, bone will change from Spongy Bone to Compact Bone, and back again

Answer 16

True

Question 17

Osteoid

Answer 17

Non-cellular matrix

Question 18

Organic Compounds

Answer 18

1. Provides flexibility
2. Primarily collagen fibers
3. Resists twisting and tension

Question 19

Inorganic Compounds

Answer 19

1. Provides durability and hardness
2. Calcium and Phosphate
   
   1. 98% of calcium held in bone

Question 20

Bone cells

Answer 20

1. Osteoclast
2. Osteoprogenitor cells
3. Osteoblast
4. Osteocyte

Question 21

Osteoclast

Answer 21

1. Derived from WBC
2. Breaks down old matrix (osteoid)
3. Releases calcium and phosphate

Question 22

Osteoprogenitor Cell

Answer 22

1. Will form all new bone cells
2. Can divide

Question 23

Osteoblast

Answer 23

1. Immature bone cells
2. Secretes new matrix (osteoid)

Question 24

Osteocyte

Answer 24

1. Mature bone cells
2. Trapped cell in lacunae
3. “Resident” cell

Question 25

Canaliculi Transfer

Answer 25

Wastes, nutrients, gases, etc. diffuse from cell to cell due to the mineralized matrix which allows no diffusion

Question 26

Intramembranous Ossification

Answer 26

1. Forms mainly flat bones of skull
2. Bone develops between layer of fibrous membrane
3. Can be seen in fontanels (baby’s soft spots)

Question 27

Endochondral Ossification

Answer 27

1. Forms mainly long bones of body (especially appendages)
2. Cartilage Model formed first
3. Bone replaces cartilage over time
4. Some cartilage remains at epiphyseal plate (until growth ends) and ends of bones (for life)

Question 28

Appositional Growth

Answer 28

Growth of bone in width

bone cells lay down new bone tissue along outside of bone (deep to the periosteum)

Question 29

Interstitial Growth

Answer 29

Growth of bone in length

Bone replaces cartilage, where cartilage cells have died

Occurs along epiphyseal plate

Question 30

Classification of Bone by Shape

Answer 30

• Flat Bones → Cranial skull bones (parietal bone)
• Long Bones → Bones of appendages
• Short Bones → Cube-like bones (carpals, tarsals)
• Irregular Bones → Variable shape (vertebrae, coxal bone)
• Sesamoid Bones → Sesame seed shape (patella)