Lecture 10

Question 1

List three types of cartilage

Answer 1

• hyaline
• elastic
• fibrocartilage

Question 2

What are the major characteristics of hyaline cartilage? Where is it located?

Answer 2

Hyaline cartilage is:
- most common
- type II collagen
- surrounded by perichondrium
- bluish grey/white
- grows appositionally, and interstitially
Is found in the Larynx, fetal long bones, articular ends of bones, bronchial and tracheal cartilages, and the external auditory meatus

Question 3

What are the major characteristics of elastic cartilage? Where is it located?

Answer 3

Elastic cartilage is:
- yellow in color
- more opaque, flexible, and elastic than hyaline cartilage
- type II collagen
- surrounded by perichondrium
It is found in the auricle of the ear, and the epiglottis

Question 4

What are the major characteristics of fibrocartilage? Where is it located?

Answer 4

Fibrocartilage is:
- lacks a perichondrium
- type I collagen
- reduced cellularity
- opaque in appearance
It is found in the intervertebral discs, knee discs, mandible, sternoclavicular joints, and pubic symphysis.

Question 5

What are some types of cells associated with cartilage structure?

Answer 5

• chondroblasts
• chondrocytes
• collagen fibers
• GAGs
• Hyaluronan
• chondroitin, heparin, and keratan sulfates

Question 6

List the subdivisions of the matrix in hyaline cartilage?

Answer 6

• territoral matrix

- inter-territorial matrix

Question 7

What are the general functions of cartilage?

Answer 7

• compressible
• resists distortion
• shock absorber
• reduces friction
• bone repair and growth

Question 8

Describe the territorial matrix.

Answer 8

The territorial matrix surrounds each chondrocyte. It has a high GAG content, and low collagen content.

Question 9

Describe the Inter-territorial matrix.

Answer 9

The inter-territorial matrix surrounds the territorial matrix. It has a high collagen, low GAG content.

Question 10

The structure of cartilage contains 3 major components, what are they?

Answer 10

• perichondrium
• isogenous groups
• matrix

Question 11

What does avascular mean to cartilage?

Answer 11

• Avascularity in cartilage means that nutrients and oxygen are derived from surrounding blood vessels, and must diffuse through the matrix.
• Very slow healing

Question 12

What is the main difference between a chondrocyte and a chondroblast?

Answer 12

Chondroblasts lay down the cartilage matrix, and eventually become chondrocytes that maintain the matrix.

Question 13

What are lacunae?

Answer 13

Lil pockets in the matrix where the chondrocytes and chondroblasts are found.

Question 14

List the three three types of bone tissue:

Answer 14

• spongy
• woven
• compact

Question 15

What are the characteristics of woven bone?

Answer 15

• present during bone development and repair
• rapidly produced
• collagen formation is haphazard
• not much structural integrity

Question 16

What are the characteristics of spongy bone?

Answer 16

• consists of a bony spicule lattice intertwined to form trabeculae
• also called “trabecular” or “cancellous” bone

Question 17

What are the characteristics of compact bone?

Answer 17

• also called “lamellar” bone
• lacks cavities
• forms the dense plate on the outside of long or flat bones
• consists of haversian systems, osteocytes, and volkmanns canals

Question 18

What is the general structure of an osteon (haversian system)?

Answer 18

Haversian lamellae encircle a central blood vessel and the associated nerves.

Question 19

Where are osteocytes found?

Answer 19

Osteocytes are found between the lamellae in the lacunae, they are connected to each other and the haversian canal via canaliculi.

Question 20

What is the canalicular structure of compact bone?

Answer 20

Canaliculi connect osteocytes to haversian canals and other osteocytes in compact bone. It is the inorganic part of the bone.

Question 21

What are the four cell types involved with bone formations, maintenance, and reabsorption?

Answer 21

• osteocytes
• osteoblasts
• osteoclast
• osteoprogenitor cells

Question 22

What is the relationship between osteoblasts and monocytes in osteoclast formation? (steps, its easier)

Answer 22

1. Parathyroid binds to receptors on osteoblast
2. osteoblast synthesizes and releases M-CSF (monocyte colony stimulating factor) that binds to monocytes
3. Monocyte is now a macrophage expressing RANK that causes binding between the macrophage and osteoblast
4. macrophage becomes immature osteoclast
5. osteoblast secretes osteoprotegerin that binds to RANKL
6. Non-functional osteoclast becomes a functional osteoclast

Question 23

Describe the biochemical mechanisms used by osteoclasts to reabsorb bone.

Answer 23

Osteoclasts secrete:

• cathepsin k that catabolizes elastin, collagen, and the organic matrix
• H, Cl ions that dissolve the inorganic matrix

Question 24

What is the function of an osteoblast?

Answer 24

Osteoblasts are derived from osteoprogenitor cells, they synthesize the organic osteiod and control the mineralization of the matrix.