ANSWERS

1. There are 4 types of tissue within the body: muscular, nervous, epithelial and connective. State which tissue type bone and cartilage belong to.
   Both are types of connective tissue.
2. Describe broadly the function of connective tissue.
   It binds all the other body tissues together providing support. It also acts as a transport system.
3. What is the name given to the intercellular material found among the cells of connective tissue?
   Ground substance.
4. List the components of bone tissue.
   • Calcium phosphate (and other calcium containing minerals).
   • Collagen fibres.
   • Ground substance (mucopolysaccharide polymer).
   • Osteocytes (bone cells).
5. What is the name of the tough, fibrous tissue that covers all bones?
   The periosteum.
6. Bones are comprised of many layers of tissue. What is the name given to such layers?
   Lamellae.
7. What is the name given to spaces within the bone lamellae?
   Lacunae.
8. Bones are classified according to their shape. List the 4 types and give an example of each.
   • Long bones - the femur.
   • Flat bones - the scapula.
   • Irregular bones - vertebrae.
   • Short bones - the carpal and tarsal bones.
9. Name the 2 types of bone tissue. Where is each found?
   • Compact bone - the hard white substance found in the outer layer of all bones.
   • Spongy bone (also known as cancellous bone) - found in the ends of long bones and the core of short and flat bones.
10. What is the name of the complex series of canals which permeate bone, containing blood and lymph vessels to maintain its nutrition?
    Haversian systems.
11. What is the difference between compact and spongy bone?
    The Haversian systems in spongy bone are more widely spread apart than in compact bone. In spongy bone, the spaces between the Haversian canals are filled with red bone marrow (made up of fat and red blood cells).
12. What is the name given to the dividing bands which hold the functioning bone cells in position giving strength but without adding too much weight?
    Trabeculae; these make up the 3-dimensional network of bars and plates that form spongy bone. Each trabecula consists of a few lamellae arranged parallel to one another or concentrically.
13. Describe the composition of long bones.
    Long bones comprise a shaft (body) and two ends (the proximal end may be known as the head). They have an outer layer (cortex) of compact bone, and spongy bone at each extremity. They possess a medullary cavity filled with bone marrow, although most blood cell formation occurs within the spongy bone.
14. Describe the composition of flat and irregular bones.
    Both flat and irregular bones consist of a layer of spongy bone sandwiched between 2 layers of compact bone.
15. What is meant by a foramen or foramina?
    A channel through the bone which allows the passage of blood and nerves.
16. What is meant by a fossa?
    A hole or depression within a bone.
17. What is the difference between a condyle and an epicondyle?
    A condyle is a round prominence of a bone forming part of an articular surface, whilst an epicondyle is a bony prominence on a condyle which is usually a site for soft tissue attachment.
18. Describe cartilage.
    A dense, clear, blue-white, tough connective tissue found principally at joints and between bones. It does not contain blood vessels, but derives its blood supply from an outer membrane called the perichondrium.
19. What are cartilage producing cells known as?
    Chondrocytes.
20. Name the 3 different types of cartilage. Where in the body is each type found?
    • Hyaline - forms the rings of the trachea and the articular surfaces of joints.
    • Fibrocartilage - surrounds and deepens articular sockets of some bones e.g. the acetabulum of the pelvis, also forms the intra-articular cartilages (menisci) of the stifle as well as contributing to the structure of the intervertebral discs and parts of the ribs.
    • Elastic cartilage - found in the pinna and epiglottis.
21. Which is the strongest of the types of cartilage listed in your answer to Q20, and why?
    Fibrocartilage; this is due to its increased amount of collagen fibres.
22. What is the term used to describe the development of bone?
    Ossification.
23. What are the 2 methods of ossification (bone formation)? Briefly describe each.
    • Endochondral ossification - this is the main form of bone production within the body and starts from a very early stage in embryonic development. A cartilage template is laid down by chondroblasts which is invaded by blood vessels and osteoblasts (these eat up cartilage and lay down the bone matrix). Once the osteoblasts have laid down sufficient bone, they become trapped and are know termed osteocytes. Bone is remodelled and absorbed by osteoclasts which go on to form the medullary bone cavity.
    • Intramembranous ossification - this is where bone is formed between 2 layers of periosteum.
24. What might endochondral ossification also be known as?
    Interchondral ossification.
25. Give an example of bones formed by intramembranous ossification.
    The flat bones of the skull.
26. What is the area of bone development within the shaft of a bone called?
    The diaphysis.
27. What are the areas of bone development within the ends of a bone called?
    Epiphyses.
28. The developing diaphysis and epiphyses are separated by a strip of cartilage called the epiphyseal plate. This is where growth continues until the plate is obliterated by bone tissue, at which point the bone no longer increases in length. What is another name for the epiphyseal plate?
    Growth plate.
29. The bone of a young animal is relatively smooth. Give 3 reasons why the bone of an elderly animal may show roughened areas.
    • Trauma; periosteum pulled away from the bone.
    • Remodelling at the site of damaged tendons.
    • Arthritic changes.
30. At what age might one expect completion of ossification in a small to medium sized dog?
    6-9 Months.