Bone Tissue - Tutorial 2

Question 1

Label the structures of the long bone and describe the function of each section (e.g. diaphysis)

Answer 1

Diaphysis - is the shaft of long bone, long and cylindrical, outer layer of compact bone, medullary cavity containing yellow bone marrow and blood vessels

Epiphyses - form the proximal and distal ends of a long bone.

Question 2

Briefly explain how bones grow in length (where does this growth occur)

Answer 2

Metaphyses - (meta = after, between) - growth in length occurs the growth plate (epiphyseal plate)

Question 3

Describe the location of the periosteum

Answer 3

A connective tissue sheath that wraps around the external surface of bone wherever it isn’t covered by articular cartilage

Question 4

State four functions of the periosteum

Answer 4

• Protects bone
• Point of attachment for ligaments and tendons
• Nourishes bone tissue
• Helps in fracture repair

Question 5

Explain why severe pain occurs with bone fractures and bone marrow puncture

Answer 5

• Rich in sensory nerves which are very sensitive to tearing or tension
• Severe pain results from fractures and bone tumours
• Bone marrow punctures are painful as the needle penetrates the periosteum

Question 6

Name the two types of bone tissue

Answer 6

compact
spongy

Question 7

Describe the location of each type, the structures in each and the specific functions of each type

Answer 7

Compact
Location: Dense, smooth solid outer layer of bones, there is only compact bone on the diaphysis (shaft) of long bones

• Functions: Protection and support of spongy bone, blood vessels and nerves
• Resists stresses produced by weight and movement
• Structure: Made up from osteons that are arranged parallel to the diaphysis of long bones - giving the bone strength

Spongy bone
- Location: always in the interior of bones

• Functions: Lightweight which means it can be moved by skeletal muscle contraction
• Protects bone marrow
• Red bone marrow (blood cell production)
• Yellow bone marrow (adipose tissue)
• Bone marrow provides nutrients to osteocytes

Structure: Less dense than compact bone as it contains bone marrow, fine trabeculae

Question 8

Describe three structural differences between the two types

Answer 8

Compact
- Consists of osteons with little spaces between them
- Forms the exterior surface of bones and covers spongy bone
- Is the strongest form of bone (protects, supports, resists stress)

Spongy
- Does not contain osteons but consists of trabeculae
- Houses bone marrow
- Forms the interior of the epiphysis of long bones and most of the structure of short, flat bones
- Makes bones lighter and easier to move

Question 9

Name two main types of cartilage

Answer 9

• Hyaline Cartilage
• Fibrocartilage
• Elastic cartilage

Question 10

• Describe the components of bone tissue

Answer 10

Is connective tissue comprised of 4 different types of bone cells, extracellular matrix that surrounds bone cells contains water (15%), collagen fibres (30%), crystallized mineral salts (55%)

Question 11

Name and describe the specific functions of the four bone cells

Answer 11

• Stem cell (osteogenic cells): Develops into osteoblast
• Osteoblasts (bob the builder): Bone forming cells that produce bone matrix
• Osteocytes (maintain the bone matrix): exchange nutrients and wastes in the extracellular matrix
• Osteoclasts (collapsing clint): release enzymes to breakdown bone - called bone resorption

Question 12

Name the main type of fibre in the extracellular matrix and state the function
of this fibre

Answer 12

Collagen fibres (30%) - these fibres give bone it’s flexibility and strength to resist being torn

Question 13

State the location, structure and function of the osteons

Answer 13

• Structure: tiny weight bearing pillars that have layers of collagen fibres in opposing directions
• Location: each osteon has a central canal that contains blood vessels and a nerve
• Function: give the strength and resistance to compact bone

Question 14

Describe the action of each hormone and how each hormone affects blood calcium (Ca2+) levels

Answer 14

• PARATHYROID HORMONE (PTH) released from parathyroid glands RASIES THE BLOOD CALCIUM LEVELS levels by stimulating the osteoclasts to break down bone. This RELEASES CALCIUM INTO THE BLOOD
  If blood calcium levels are to high calcitonin is released from the thyroid gland to inhibit the activity of osteoclasts, preventing bone resorption. It LOWERS BLOOD CALCIUM LEVEL

Question 15

State five factors that could delay bone healing

Answer 15

• Tissue fragments between the bone ends that haven’t been removed by phagocytes
• Deficient blood supply
• Poor alignment of the bone ends
• Continued mobility of bone ends
• Illness, malnutrition, drugs, aging

Question 16

Define osteoporosis

Answer 16

• Osteoporosis is a disease in which there is significant loss of bone mass (bone density) and impaired structural integrity of bone

Question 17

Describe four age related changes of the skeletal system

Answer 17

1. Bone becomes more brittle and prone to fracture due to:
   - Reduction in bone mass density - this results from demineralisation of bone (the loss of calcium and other minerals from the extracellular matrix)
   - Reduction in collagen due to decreased synthesis of collagen (protein)
2. Articular cartilages diminish and thins
   - Bones move against one another and lead to rough bony growths
   - Leads to osteoarthritis causing pain and decreased mobility
3. Height is reduced due to
   - Compression of the interverbal discs (through fluid loss)
   - Osteoporosis of the vertebrae
4. Rigidity of the thoracic cage as costal cartilage ossifies
   - Produces shallow breathing resulting in less efficient gas exchange