Skeletal System (Ch. 5)

Question 1

Functions of the skeletal system

Answer 1

1. Support
2. Protection - ribs, skull, vertebrae
3. Leverage - muscles pull on bones
4. Blood cell production -bone marrow produces erythrocytes, leukocytes, and platelets
5. Storage of minerals - calcium, phosphate ions

Question 2

Characteristics of bones

Answer 2

1. Bone is a composite material
   - Made from 2 classes of material:
   (1) Inorganic: 70% calcium phosphate – very strong, inflexible, resist compressive forces
   (2) Organic: 30% collagen fibers – tough, flexible, tensile strength, resists stretching forces
2. Bone remodels under the influence of forces (stress)
3. Bone is stronger in one plane, weaker in another

Question 3

Osteoproginitor cell

Answer 3

-bone stem cell
- differentiate to form new osteoblasts
- heavily involved in the repair of bones after a break

Question 4

Osteocytes

Answer 4

• mature bone cell
• entrapped by body tissue
  
  • lacunae – layers called laminae
• Monitor and maintain protein and mineral content of the matrix
• small channals extending from osteocytes to bone capillaries called canaliculi

Question 5

Canaliculi

Answer 5

Small channels extending from osteocytes to bone capillaries
- provide a route for nutrients and waste products from one osteocyte to another across gap juntions

Question 6

Lacunae

Answer 6

Small chambers that osteocytes occupy
- connected by canaliculi
- sandwiched between layers of calcified matrix -ie lamellae

Question 7

Lamallae

Answer 7

layers of calcified matrix sandwiching lacunae

Question 8

Osteoblasts

Answer 8

Cuboidal cells
- make new bone cells (osteogenesis)
- produce and secrete osteoid (collagenous material- later mineralize and form matrix)
- differentiate into osteocytes when entrapped

Question 9

Osteoid

Answer 9

Collagenous material that will later mineralize into the matrix
- secreted by the osteoblasts in osteogenesis

Question 10

Osteoclasts

Answer 10

Large, multinucleated - form precursor blood cells
- secretes acids which dissolves bone
- causes the release of stored calcium ions and phosphate ions into the blood
- found where bone is being removed
(osteolysis)

Question 11

Epiphysis

Answer 11

End of long bones
- consists of red marrow

Question 12

Diaphysis

Answer 12

Shaft of long bone
- medullary cavity consists of yellow marrow

Question 13

Metaphysis

Answer 13

Narrow growth zone between epiphysis and diaphysis

Question 14

Spongy bone

Answer 14

Open network of struts and plates (trabeculae)
Surrounds medullar cavity – consisted on bone marrow
- supports/protects red marrow in the epiphysis of bone

Question 15

Compact bone

Answer 15

(dense bone)
- forms the wall of the bone
- consists of osteons -> basic functioning unit of bone
- osteon arrangement is parallel to bone axis = lots of strength

Question 16

Periosteum

Answer 16

Outer surface of bone
- actively involved in repair and growth
- provides attachment for circulatory and nervous supply
-highly innervated

Question 17

Endosteum

Answer 17

Inner surface of bone
- actively involved in repair and growth
- lines medullary cavity
- one cell thick and incomplete
- consists of osteoprogenitor cells