L2 Cartilage and Bone Structure

xibocutie's version from 2017-01-03 16:38

Overview of Cartilage

Question Answer
How does cartilage get its nutrients?Diffusion b/c cartilage is avascular. Matrix controls diffusion of nutrients. Low O2 environment.
Hyaline Cartilagehomogeneous matrix
Elastic Cartilagecontains elastic fibers
Fibrocartilagefibrous connective tissue--predomin. type I collagen
Chondrogenic cellsin Perichondrium. Differentiate into chondroblasts
Chondroblastsalong outside edge of matrix
Chondrocytesembedded w/in matrix
Chondroclastsaka osteoclasts. Action-cartilage degradation.

Hyaline Cartilage

Question Answer
What type of cartilage makes the fetal skeleton precursor to long bones?Hyaline Cartilage
In adults, where can you find hyaline cartilage?Joint surfaces (articular surfaces) and in some parts of respiratory system
Chondroblasts are located where?Along outside edge of cartilage
Chondrocytes are located where?Within cartilage in Lacunae
How do lacunae look in histology sections?Somewhat empty b/c of cell shrinkage during section processing
Hyaline Cartilage has what type of collage for its extracellular matrix?Type II Collagen
Type II collagen fibrils are thicker or thinner than Type I collagen?Type II is thinner fibrils (20 nm) vs (50-200 nm for Type I)
What is the major proteoglycan in hyaline cartilage?Aggrecan. (amorphous ground substance)
What is aggrecan composed of?Made of proteogylcans (w/chondroitin sulfate/keratin sulfate) that bind to a hyaluronic acid backbone and stabilized by link protein
What is the territorial matrix?The region where it is stained darkest, around lacunae, due to the high proteoglycan sulfate content
Why does cartilage stain result in basophilic stain in the matrix?Due to high proteoglycan sulfate content. Stain darkest around lacunae.
What is responsible for the resilience/strength of cartilage?The well hydration of cartilage matrix. Made of 60-80% water, water bound to aggrecan makes it strong
What is perichondrium?Dense connective tissue surrounding cartilage (similar to a capsule)
What are the two layers of perichondrium?Outer Fibrous Layer and Inner Cellular Layer
Outer fibrous layer of perichondrium contains?Type I Collagen, fibroblasts, and blood vessels
Inner cellular layer of perichondrium contains?Chondroblasts and chondrogenic cells
In Perichondrium, during appositional growth, chrondrogenic cells located adjacent to cartilage matrix differentiate into what?chondroblasts
Will you find perichondrium in the cartilage at a joint?NO
How does the initial deposition of hyaline cartilage begin?Mesenchymal stem cells aggregate, differentiate into chondroblasts, secrete cartilage matrix due to BMP growth factors. Adjacent mesenchymal tissue becomes perichondrium.
Appositional growth of Hyaline cartilage1. New Cartilage is added to surface of preexisting cartilage. 2. Differentiation of chondrogenic cells into chondroblasts. 3. Chondroblasts become chondrocytes after becoming entrapped in newly secreted matrix. 4. Switch in collagen types from perichondrium to cartilage matrix