6. Bones and Cartilage

1. What is cartilage made of?

Cartilage is a type of connective tissue, made of chondrocytes and specialized ECM (95% of volume)

2. Define chondrocyte

Chondrocytes are the mature cells of cartilages

3. List the 3 types of cartilage

Hyaline, elastic, fibrocartilage

4. What is a lacuna?

In histology, a lacuna is a small space, containing an osteocyte in bone, or chondrocyte in cartilage

5. Why does cartilage have low metabolic rate?

Chondrocytes are found in lacunae surrounded by ECM. Cartilage has a low metabolism rate because of this structure.

6. Why does cartilage have poor capacity to repair?

Cartilage is avascular

7. With aging, cartilage is prone to ______

calcification

8. Cartilage undergoes 2 types of growth which are:

Appositional growth is growth from surface/outside

Interstitial growth is growth from inside of cartilage via mitosis of chondrocytes

9. ECM of all cartilage contains

Type II collagen, proteoglycans, glycoproteins

10. ECM of elastic cartilage contains

• Collagen type 2

• Proteoglycans

• Glycoproteins

• Elastic fibers

11. The ECM of fibrocartilage contains

Collagen type I and II, proteoglycans, glycoproteins

12. Main fibre in bone tissue is?

collagen type I

13. What is the most widespread type of cartilage?

Hyaline cartilage

14. Where can hyaline cartilage be found?

• articular surfaces of synovial joints,

• costal cartilages (ribs)

• nose, larynx, trachea, bronchi

15. Hyaline cartilage plays a key role in:

• Development of fetal skeleton (endochondral ossification - most bones begin as models of pure hyaline cartilage)

• Growth in length of long bones (found epiphyseal growth plates)

16. What is perichondrium?

The connective tissue that envelops cartilage when it is not at a joint

17. Where is elastic cartilage found?

pinna of ear, epiglottis (in larynx) and auditory tube

18. What material gives elastic cartilage its elasticity?

Elastin

19. Where is fibrocartilage found?

Found where there is lot of compressive/shearing force e.g.

• Intervertebrae disc

• pubic symphysis (between pubic bone and pelvis)

• where tendons insert into bones menisci of knee joints

20. Fibrocartilage is a combination of _____ and dense ______.

Fibrocartilage is a combination of hyaline cartilage and dense fibrous tissue.

21. What type of cartilage [hyaline/elastic/fibrocartilage] is NOT surrounded by perichondrium.

Fibrocartilage

22. Bone is a specialised type of CT characterised by mineralised ________ that stores ______ and ______.

Bone is a specialised type of CT characterised by mineralised ECM that stores calcium and phosphorous.

23. The external surface of the bone is covered by _______, which contains a layer of ________ that can differentiate into bone-forming cells. The internal surfaces of bone are lined by________, a single layer of cells that includes osteoprogenitor cells, osteoblasts and osteoclasts.

The external surface of the bone is covered by periosteum, which contains a layer of osteoprogenitor cells that can differentiate into bone-forming cells. The internal surfaces of bone are lined by endosteum, a single layer of cells that includes osteoprogenitor cells, osteoblasts and osteoclasts

24. Mature bone is classified as either:

Compact bone or spongy bone

25. Distinguish between haversian canal and haversian system.

A Haversian canal is a narrow, central channel containing blood vessels and nerves. The Haversian system, (aka osteon), includes the Haversian canal and the surrounding concentric rings of bone tissue (lamellae)

26. Spongy bone is also known as

trabecular or cancellous bone

27. Lamellae in spongy bone are organised into _______ forming a 3D network. Bone marrow located in spaces between trabeculae.

Lamellae in spongy bone are organised into trabeculae/spicules/beams forming a 3D network. Bone marrow located in spaces between trabeculae.

28. Define osteoprogenitor cells

precursor cells that self-replicate or differentiate into osteoblasts

29. Define osteoblasts

bone-forming cells that deposit osteoid (organic bone) and control subsequent mineralisation.

30. Define osteocytes

Mature bone cells. Derived from osteoblasts that become surrounded by newly-formed bone. Located in lacunae of bone.

31. Define osteoclasts

Macrophage-type cells that reabsorb bone during bone remodeling.