Cartilage & Bone (Smith) Week 3 Flashcards Preview

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Flashcards in Cartilage & Bone (Smith) Week 3 Deck (21):

Name the 3 types of CARTILAGE

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


Name the 2 types of Bone

Compact & Spongy


What are some ways Cartilage is different than Bone

More flexible, Avascular, No NERVE fibers

Also, remember - ALL bone starts out as cartilage.


Name the 2 types of cells found in Cartilage

1. Chondroblasts: Immature (undifferntiated) cells
2. Chondrocytes: Mature cells


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

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


What is Perichondrium?

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


What does the loss of Chondroitin sulfate lead to?



Where can Hyaline cartilage be found?

Articular surfaces
Costal cartilages
Respiratory Cartilages
Nasal Cartilage

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


Fun facts about Fibrocartilage

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


Fun facts about Elastic Cartilage

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


Name the Functions of bone

-assisting movement
-mineral homeostasis
-Blood cell production


Why is Bone remodeling important?

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

All bone growth is by apposition


What are Osteoblasts

"Bone Builders"
-Modified fibroblasts, lay Type I collaged


What are Osteoclasts

Erode and absorb bone


What are Osteocytes

Mature bone cells formed when osteoblasts mature


What are the 3 Hormones that regulate Ca+ Homeostasis?

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)


Explain what how PTH and Calcitonin interact

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


Other hormones that impact Ca+ metabolism

Glucocorticoids - lower plasma Ca levels

Just know that Glucocorticoids decrease bone strength


Where do Osteoclasts attach in the bone?

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


Describe How PTH indirectly activates Osteoclasts

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.


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

1,25 - Dihydroxycholecalciferol AKA Calcitrol

Deactivated - 7 - Dehydrocholesterol