Bone And Cartillage

Question 1

Describe Cartillage

Answer 1

Mature type of connective tissue

• has cells (chondroblasts) which produce and (chondrocytes) which maintain the extracellular matrix
• Solid and firm but somewhat pliable
• Outer surface covered by a connective tissue layer called perichondrium
• Avascular- relies of diffusion for most of its nutrients and exchange of gases

Question 2

What are the types of cartilage?

Answer 2

1. Hyaline cartilage
2. Fibrocartilage
3. Elastic cartilage

Question 3

What are the functions of cartilage?

Answer 3

• Plays a major role in fetal development of the skeleton
• Provides the epiphyseal plates that allow for growth of the skeleton after birth
• Provides smooth articular surfaces for joints
• Absorbs shear forces or shock forces in some joints

Question 4

Describe hyaline cartilage

Answer 4

Most abundant cartilage in the body
-Collagen fibers thin not visible

• Chondrocytes in lacunae
• Outer surface covered by perichondrium (except articular cartilage )

Question 5

What are the functions of hyaline cartilage ?

Answer 5

Provides flexibility, shock absorption and support

• found in trachea, bronchus, larynx, epiglottis , ends of ribs
• Articular cartilage reduces friction for joint surfaces

Question 6

Describe fibrocartillage

Answer 6

Chondrocytes scattered among thick bundles of collagen fibers in extracellular

• No perichondrium
• Combines strength and rigidity

Question 7

Where is the fibrocartilage found?

Answer 7

Articular discs (intervertebral, symphysis pubic, meniscus, TMJ)

Question 8

Describe elastic cartilage and give its function

Answer 8

• Chondrocytes located in a threadlike network of elastic fibers in extracellular matrix
• Provides strength and elasticity and maintains shape e.g. external ear, tip of nose

Question 9

Contrast and compare growth and repair

Answer 9

• Once fully formed cartillage is relatively inactive and grows slowly
• Repairs is slow and often fails because its Avascular

Question 10

What are the types of growth?

Answer 10

Interstitial Growth
-initial type

-mainly hyaline

Appositional growth

Question 11

What is interstitial growth?

Answer 11

Initial type for all cartillage

Growth within tissue

Rapid due to cell division and increasing amounts of extracellular matrix

-Chondrocytes are pushed away from each other

Question 12

What is appositional growth?

Answer 12

Follows interstitial growth

• Occurs on outer surface
  
  • perichondrium cells differentiate into chondroblasts
• As cells produce extracellular matrix they turn into Chondrocytes
• Results in increase in width of the structures
• Occurs in all cartillage except fibrocartilage and Articular cartilage

Question 13

What is osteoarthritis?

Answer 13

• Age related degeneration of Articular cartilage followed by failed attempts at repair
• The cartilage b3comes thin and weak resulting in tears
• In a attempt to repair, bone Spurs form decreasing the joint space
• Affects mainly large weight bearing joints

Question 14

Define bone

Answer 14

Specialized connective tissue with cells (osteocytes) and extracellular matrix (mineralized)

Question 15

What are the types of bones?

Answer 15

Different types of bones serve different functions

• Protection, support, levers, weight bearing etc.
• Categorized based on shape

Question 16

What are osteoblasts?

Answer 16

Bone cells/osteoblasts- produce bone matrix and become osteocytes when trapped in lucanae

• Osteocytes maintain bone matrix and are connected to adjacent cells by cytoplasmic processes in canaculi
• Influenced by hormones

Question 17

Summarize osteoblasts formation

Answer 17

Osteogenic cell (develops into an osteoblasts) —> osteoblast (forms bone extracellular matrix) —> osteocytes (maintains bone tissue)

Question 18

What are osteoclasts?

Answer 18

• Large, multinucleated cells responsible for breakdown and resorption of bone matrix during remodeling
• Influenced by hormones

Question 19

What are the two types of bone tissue?

Answer 19

• compact (dense, thick, few spaces)

- Spongy (many spaces, often continuous forming marrow cavity)

Question 20

What is inside bone?

Answer 20

Inside of bones contain spaces that allow for vessels to enter and supply cells or as storage areas for marrow

Question 21

Is bone living tissue?

Answer 21

Bone tissue is a complex and dynamic living tissue- under constant remodeling

Question 22

Describe long bones

Answer 22

Shaft with two extremities

• diaphysis
• epiphysis
• metaphysis

Outside layer of compact bone with spongy bone inside

Marrow filled red (RBC ) or yellow marrow (fat)

-outer surface covered with periosteum (except Articular surfaces)

Long bones have a rich blood and nerve supply
-fracture = pain, blood loss

-nutrient foramen~ mid shaft for nutrient artery

Question 23

Describe compact(dense bone)

Answer 23

Strong with few spaces covered by periosteum

• mature bone is composed of cylindrical units called osteons (Haversian systems)
  
  • Concentric lamella of bone matrix
    
    • Lacuna between layers
    • Connected by canaculi
  • Central canal containing vessels (aversion canal)
    
    • connected to each other by volkmans canals

  - Continually being remodeled 
       - Remnants of osteons= interstitial lamella

Long axis of osteon is parallel to the long axis of the bone

Question 24

Describe bone lining cells

Answer 24

Contains large spaces

• Has trabeculae of lamellated matrix
• Makes up majority of tissue on the inside of short, flat and irregular bones
• forms a marrow rim around the medullary cavity of long bones
• Reducing the overall weight of bone
• supports the bone marrow

Question 25

What are the bone lining cells?

Answer 25

Located in sites where remodeling is not occurring

• flat cells with attenuated cytoplasm and a few organelles beyond the peri nuclear region
• Outer cells= periosteum
• Inner cells= endosteum
• Also derived from osteoblasts
• Processes extend to meet with osteocytes and serve a support role

Question 26

What is osteogenesis?

Answer 26

-formation of bone

• initial formation in embryo and fetus
  
  • intramembranous ossification
    
    • mainly flat bones
• Endochondrial ossification
  
  • Mainly long bones
  • Articular surfaces

Question 27

Contrast interstitial and appositional growth

Answer 27

Interstitial growth
-In fetus.

-mainly at epiphyseal growth plates (cartilage)

Appositional growth
-Same as in cartilage but from periosteum

Question 28

Explain maintenance of bone

Answer 28

• Remodelling is a process of continual breakdown (osteoclasts) and production (osteoblasts) of exteacellular matrix
• Keeps the bone healthy
• Bone reacts to stress- “bumps” and roughenings on bones that serve as attachments for muscles is evidence of that
• Excess bone formation on external surface of bones prone to bear weight= osteophytes

Question 29

Explain repair fracture healing

Answer 29

• A hematoma forms at the site of fracture
• Formation of soft callus (fibroblasts, chondroblasts, osteoblasts)
• Soft callus remodeled into bony or hard callus by osteoblasts and osteoclasts

Process:
1. Formation of fracture hematoma

2. Fibrocartilaginous callus formation
3. Bony callus formation
4. Bone remodelling