Module One, Lecture Four

Question 1

Describe the composition of Bone Tissue…

Answer 1

1. The Organic Bit ( 33% of the ECM is organic, mainly collagen )
2. The Inorganic Bit ( 66% of the ECM is inorganic, composed of calcium and phosphorus )

Question 2

Name the four main type of Bone Cells… ( 4 )

Answer 2

1. Osteoprogenitor
2. Osteoblasts
3. Osteocytes
4. Osteoclasts

Question 3

Describe the structure and function of Osteoprogenitor Cells…

Answer 3

1. Flattened spindle-shaped structure when inactive
2. Plump, oval nuclei when active
3. Crucial role in bone repair and growth

Question 4

Describe the structure and function of Osteoblasts…

Answer 4

1. Typically cuboidal ( cube shaped ) or polygonal ( many sides ), large, often light staining nucleus
2. Bone formation, remodelling and healing damaged bones

Question 5

Describe the structure and function of Osteocytes…

Answer 5

1. Star shaped with numerous slender, dendrites that extend into channels called canaliculi
2. Maintaining the bony matrix and regulating bone turnover

Question 6

Describe the structure and function of Osteoclasts…

Answer 6

1. Ruffled boarder and a clear zone
2. Resorb bone tissue, breaking it down and dissolving it to release calcium and other minerals back into the bloodstream

Question 7

How do bones help maintain homeostasis?

Answer 7

When blood levels of minerals are too low, bones release some of the minerals back into the blood, thus restoring homeostasis

Question 8

Describe the Physical Appearance of Compact Bone…

Answer 8

1. Outer surfaces appear dense and impenetrable
2. Foramina / holes for blood supply
3. Made up of circumferential lamellae and osteons

Question 9

How are Osteons aligned?

Answer 9

Aligned parallel to the long axis of the bone and help resist stress and bending

Question 10

Describe the structure and functions of Osteons…

Answer 10

1. Cylindrical structures that consists of a central canal containing blood vessels and nerve fibres, surrounded by a concentric layer of bone matrix called lamellae
2. Osteons provide nutrients and oxygen to bone cells ( osteocytes ) and help remove waste products

Question 10

Describe the Physical Appearance of Cancellous Bone…

Answer 10

1. Porous / honeycombed appearance
2. Interconnected plates and bars ( trabeculae )
3. These spaces are filled with bone marrow and blood vessels
4. Osteocytes are housed in lacuna in between lamellae / on the surface

Question 11

What is a Trabecular Bone?

Answer 11

Highly porous and less dense type of bone tissue found within the interior of bones, particularly at the ends of long bones, in vertebral bodies, and in flat bones

Question 12

What are some functions of Trabecular Bones? ( 2 )

Answer 12

1. Provides strength and transfers load
2. Supports metabolic functions

Question 13

How is Bone Homeostasis Maintained?

Answer 13

1. Bone is constantly being formed / destroyed ( osteoblasts / osteoclasts )
2. Allows the body to mobilise calcium, phosphate and other minerals from the bone matrix