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?
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
-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
-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.