Cartilage is a resilient and smooth elastic tissue, rubber-like padding that covers and protects the ends of long bones at the joints, and is a structural component of the rib cage, the ear, the nose, the bronchial tubes, the intervertebral discs, and many other body components. It is not as hard and rigid as bone, but it is much stiffer and much less flexible than muscle. 

Because of its rigidity, cartilage often serves the purpose of holding tubes open in the body. Examples include the rings of the trachea, such as the cricoid cartilage and carina. 

Cartilage is composed of specialized cells called chondrocytes that produce a large amount of collagenous extracellular matrix, abundant ground substance that is rich in proteoglycan and elastin fibers. Cartilage is classified in three types, "elastic cartilage", "hyaline cartilage" and "fibrocartilage", which differ in relative amounts of collagen and proteoglycan. 

Cartilage does not contain blood vessels (it is avascular) or nerves (it is aneural). Nutrition is supplied to the chondrocytes by diffusion. The compression of the articular cartilage or flexion of the elastic cartilage generates fluid flow, which assists diffusion of nutrients to the chondrocytes. Compared to other connective tissues, cartilage has a very slow turnover of its extracellular matrix and does not repair. In embryogenesis, the skeletal system is derived from the mesoderm germ layer. Chondrification (also known as chondrogenesis) is the process by which cartilage is formed from condensed mesenchyme tissue, which differentiates into chondroblasts and begins secreting the molecules (aggrecan and collagen type II) that form the extracellular matrix. QUESTIONS:

Q1:
1. Cartilage does not repair contrary to what type of tissues?
2. What type of tissues repair contrary to cartilage?
3. 
Q2:
1. Is cartilage flexible or rigid?
2. Would one use the term flexible or rigid to describe cartilage?
3. 
Q3:
1. What part of the body that is used for hearing has cartilage?
2. Cartilage is located in which part of the body that is used for hearing?
3. 
Q4:
1. What part of the body that protect internal organs contains cartilage?
2. Cartilage is part of which body part that protects the body's internal organs?
3. 
Q5:
1. How does cartilage compare to muscle?
2. Is cartilage stiffer or softer than muscle?
3. 
Q6:
1. Cartilage is made up of what kind of cells?
2. What type of cells make up cartilage?
3. 
Q7:
1. What are the cells that make up cartilage called?
2. What is the name that is given to the cells that make up cartilage?
3. 
Q8:
1. What do chondrocytes produce?
2. What is produced by chondrocytes?
3. 
Q9:
1. What is the total number of cartilage types?
2. How many categories of cartilage are present in the human body?
3. 
Q10:
1. How do the various types of cartilage differ from one another?
2. How do the different types of cartilage vary?
3. 
Q11:
1. What method is used by the body to feed cartilage?
2. How does cartilage get fed?
3. 
Q12:
1. How often is cartilage repaired in the human body?
2. With what regularity is cartilage repaired?
3. 
Q13:
1. Are there any blood vessels present inside cartilage?
2. Does cartilage have any blood vessels inside of its cells?
3. 
