Question

(answer with a paragraph or a few sentences for each)

1. The structure of cartilage (in general), how types of cartilage differ from one another, and the importance of the perichondrium associated with cartilage

2. The activity of osteoblasts, balancing osteoclast activity with osteoblast activity, and ways through which various signal molecules control osteoclast activity

3. Comparison of cartilage and bone (particularly a long bone) with respect to the blood supply that supports cells of the tissue

Answer 1

1) Cartilage is a connective tissue consisting of a dense matrix of collagen fibres and elastic fibres embedded in a rubbery ground substance. The matrix is produced by cells called chondroblasts, which become embedded in the matrix as chondrocytes.That is, mature cartilage cells are called chondrocytes.

They occur, either singly or in groups, within spaces called lacunae in the matrix.

The surface of most of the cartilage in the body is surrounded by a membrane of dense irregular connective tissue called perichondrium. This is important to remember especially because, cartilage contains no blood vessels or nerves - except in the perichondrium.

There are three different types of cartilage:
They are hyaline cartilage, fibrocartilage, and elastic cartilage.

Importance of perichondrium

Perichondriumis a type of irregular collagenous ordinary connective tissue, and also functions in the growth and repair of cartilage.

2) osteoblasts are the cells that form the bone. They are single nucleated. Osteoclasts are the cells that resorb the bone and multinucleated.

PTH stimulates bone resorption by osteoclasts, but it does so indirectly. Receptors for PTH are located on osteoblasts, which then signal to bone marrow-derived osteoclast precursors to stimulate their fusion, differentiation and activation.

3) Bone is vascularized and osteoblasts differentiate with presence of blood, while cartilage is avascular and does not need blood