Cartilage & Bone (Smith) Week 3

Question 1

Name the 3 types of CARTILAGE

Answer 1

1. Hylaine - (Type II only - thin)
2. Fibrocartilage - (Type I & II - thick)
3. Elastic Cartilage (Elastic fibers + type II)

Question 2

Name the 2 types of Bone

Answer 2

Compact & Spongy

Question 3

What are some ways Cartilage is different than Bone

Answer 3

More flexible, Avascular, No NERVE fibers

Also, remember - ALL bone starts out as cartilage.

Question 4

Name the 2 types of cells found in Cartilage

Answer 4

1. Chondroblasts: Immature (undifferntiated) cells

2. Chondrocytes: Mature cells

Question 5

Name the the 3 Types of COLLAGEN and where they are found

Answer 5

Type I: Most abundant, Found in Skin, Tendons, Ligaments, BONE & Intervertebral Discs

Type II: Less Abundant - Articular & Hyaline Cartilages and the eyes

Type III: 2nd most abundant - Intestinal walls, muscles and blood vessels also can be found with Type I

Question 6

What is Perichondrium?

Answer 6

Layer of dense irregular connective tissue found around the perimeter of elastic and hyaline cartilages but NOT in FIBROCARTILAGE

Question 7

What does the loss of Chondroitin sulfate lead to?

Answer 7

Osteoarthritis

Question 8

Where can Hyaline cartilage be found?

Answer 8

Articular surfaces
Costal cartilages
Respiratory Cartilages
Nasal Cartilage

Remember - Only hyaline cartilage has the ability to calcify into bone.

Question 9

Fun facts about Fibrocartilage

Answer 9

• strongest cartilage
• Type I & II
• Only type of cartilage to not have a PERICHONDRIUM

Question 10

Fun facts about Elastic Cartilage

Answer 10

• Elastic fibers
• Has a perichondrium
• contains type II
• Found on Ear, Auditory tube & Epiglottis

Question 11

Name the Functions of bone

Answer 11

• Support
• protection
• assisting movement
• mineral homeostasis
• Blood cell production

Question 12

Why is Bone remodeling important?

Answer 12

Throughout the life of bone, it is constantly being remodeled especially since mature osteocytes are unable to divide.

All bone growth is by apposition

Question 13

What are Osteoblasts

Answer 13

“Bone Builders”

-Modified fibroblasts, lay Type I collaged

Question 14

What are Osteoclasts

Answer 14

Erode and absorb bone

Question 15

What are Osteocytes

Answer 15

Mature bone cells formed when osteoblasts mature

Question 16

What are the 3 Hormones that regulate Ca+ Homeostasis?

Answer 16

1. (PTH) - Secreted by chief cells, mobilized Ca+ from bone
2. Vitamin D - Increases Ca+ absorption & increases Ca+ in bone
3. Calcitonin - Inhibits bone resorbtion (parafollicular cells)

Question 17

Explain what how PTH and Calcitonin interact

Answer 17

PTH - increases blood levels of Ca+ when plasma levels get too low - (stimulates Ca+ release from bone)

Calcitonin - Lowers plasma Ca+ - inhibits osteoclast activity, Stimulates Osteoblast activity

Question 18

Other hormones that impact Ca+ metabolism

Answer 18

Glucocorticoids - lower plasma Ca levels

Just know that Glucocorticoids decrease bone strength

Question 19

Where do Osteoclasts attach in the bone?

Answer 19

Osteoclasts attach to bone via integrins in isolated areas called sealing zones

Question 20

Describe How PTH indirectly activates Osteoclasts

Answer 20

PTH binds to Osteoblasts (RANKL) - which bind to osteoclast precurosors (RANK) which then differentiate to Osteoclasts.

Osteblasts also contain Osteoprotegrin which inhibits RANKL from binding to RANK. The ratio between RANKL and Osteprotegrin determines the rate of bone resorption.

Question 21

What is the name of the ACTIVE form of Vit. D?/Deactivated?

Answer 21

1,25 - Dihydroxycholecalciferol AKA Calcitrol

Deactivated - 7 - Dehydrocholesterol