Week 4 - Bone Tissue Flashcards

1
Q

Label the structures of the long bone

A
  • Diaphysis (shaft of long bone)
  • Epiphyses
  • Metaphyses
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2
Q

What is the function of the Diaphysis?

A

Responsible for supporting the weight of the body as columns and, at the same time, increase the power of the muscles working as a lever.

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3
Q

What is the function of the Epiphyses?

A

Aids in the growth of bone length

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4
Q

What is the function of the Metaphyses?

A
  • Growth in length occurs at the growth plate (epiphyseal plate)
  • Transfer loads from weight-bearing joint surfaces to the diaphysis (In adults)
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5
Q

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

A

The growth plate (Epiphyseal plate) is located in the metaphyses (which is located between the middle and the end of the long bones)

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6
Q

Describe the location of the periosteum

A

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

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7
Q

State four functions of the periosteum

A
  • Protects bone
  • Point of attachment for ligaments and tendons
  • Nourishes bone tissue
  • Helps in fracture repair
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8
Q

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

A

The Periosteum is rich in sensory nerves which are very sensitive to tearing or tension

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9
Q

Name the two types of bone tissue

A
  • Compact

- Spongy

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10
Q

Location of Compact bone

A

Dense, smooth solid on the outer layer of bones

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11
Q

Function of compact bone

A
  • Protection and support of spongy bone, blood vessels and nerves
  • Resists stresses produced by weight and movement
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12
Q

What is the structure of compact bone?

A
  • Made up from Osteons that are arranged parallel to the diaphysis of long bones (this gives the long bones strength)
  • Within and between the osteons is extracellular fluid that contains osteocytes to maintain the bone tissue (this enables the exchange of nutrients and oxygen and removal of waste)
  • Osteons give the strength and resistance to compact bone
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13
Q

Location of Spongy bone

A

Always in the interior of bones

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14
Q

Function of spongy bone

A
  • Lightweight which means it can be moved by skeletal muscle contraction
  • Protects bone marrow (red and yellow)
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15
Q

What does bone marrow provide?

A

Nutrients to osteocytes

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16
Q

What is the structure of spongy bone?

A
  • Less dense than compact bone as it contains bone marrow
  • Fine trabeculae ‘Little Beams’
  • Oxygen and nutrients pass from blood vessels that surround the trabeculae
  • Trabeculae are positioned along lines of stress - resist stress
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17
Q

Describe three structural differences between the two types of spongy and compact bones

A
  • SPONGY:
    • Consists of trabeculae (does not contain osteons)
    • Forms the interior of the epiphysis of long bones
      and most of the structures of short, flat bones
    • Makes bones lighter and easier to move
    • Houses bone marrow
  • COMPACT:
    • Consists of osteons with little space between them
    • Forms the exterior surface of bones and covers
      spongy bone
      • Is the strongest form of bone (protects, supports,
        resists stress)
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18
Q

Name two main types of cartilage

A
  • Hyaline cartilage

- Fibrocartilage

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19
Q

Location for Hyaline cartilage

A
  • Supports external nose (nasal cartilage)
  • Covers ends of most bones at movable joints (articular cartilage)
  • Connect ribs to sternum (costal cartilage)
  • Also in the larynx, trachea, bronchi & bronchial tubes
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20
Q

Function of Hyaline cartilage

A
  • Provides smooth surfaces for joint movement

- Provides support & flexibility for joints

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21
Q

Location of Fibrocartilage

A
  • At sites subject to both pressure and stretch
    - Intervertebral discs
    - Pubic symphysis
    - Cartilage pads in knee (Minisci)
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22
Q

Function of fibrocartilage

A

To support and join structures together

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23
Q

Where does the Extracellular matrix surround?

A

Bone cells

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24
Q

What does the Extracellular matrix contain?

A
  • Water
  • Collagen Fibres
  • Crystallized mineral salts
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25
Q

Name the 4 different bone cells

A
  • Stem cells
  • Osteoblasts
  • Osteocytes
  • Osteoclasts
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26
Q

Function of stem cells

A

Develops into osteablast

27
Q

Function of osteoblasts

A

Bone forming cells that produce bone matric

28
Q

Function of osteocytes

A

Exchange nutrients and wastes in the extracellular matrix

29
Q

Function of Osteoclasts

A

Release enzymes to breakdown bone - called bone resorption

30
Q

Name the main type of fibre in the extracellular matrix

A

Collagen fibres

31
Q

What is the function of collagen fibres?

A

These fibres give bone its flexibility and strength to resist being torn

32
Q

Explain the difference between the epiphyseal plate and the epiphyseal line

A
  • In adults, the epiphyseal cartilage is no longer present and elongation of bones has stopped.
  • The epiphyseal growth plate becomes an “epiphyseal line” as growing cartilage is replaced by calcified bone. As a bone matures, the epiphyseal plate progresses to an epiphyseal line.
33
Q

Explain what occurs during bone remodelling

A

Is the continual replacement of old bone tissue with new bone tissue that is more resistant to fracture.

34
Q

What would happen if bone remodelling doesn’t happen?

A

If this didn’t occur then the bone would become very brittle and more prone to fracture

35
Q

Define the term bone deposit

A

Addition of collagen fibres and minerals to bone

36
Q

What cell is involved with bone deposit?

A

Osteoblasts

37
Q

Define the term bone resorption

A

Removal of collagen fibres and minerals

38
Q

What cell is involved with bone resorption?

A

Osteoclasts

39
Q

State three factors that affect bone remodelling

A
  • Genetic Factors
  • Mechanical and gravitational forces on the skeleton
    § Exercise
    § Bed rest
    § Sedentary lifestyles
  • Blood calcium levels
40
Q

What is bone remodelling?

A

Part of the fracture repair process as it removes the injured bone tissue and produces new bone tissue that is more resistant to fracture

41
Q

Name the two hormones that control bone remodelling

A
  • Parathyroid

- Calcitonin

42
Q

What is the action of Parathyroid? How does it impact on blood calcium levels?

A
  • Released from the parathyroid glands raises the blood calcium levels by stimulating the osteoclasts to break down bone.
    - This releases calcium into the blood
43
Q

What is the action of Calcitonin? How does it impact on blood calcium levels?

A
  • Released from the thyroid gland when blood calcium levels are too high to inhibit the activity of osteoclasts, preventing bone resorption.
    It lowers the blood calcium level
44
Q

What are the 4 stages of bone healing IN ORDER

A
  1. Fracture haematoma forms
  2. Soft procallus forms
  3. Bony callus
  4. Bone remodelling
45
Q

Explain what happens during Fracture Haematoma formation, and how long after injury it happens?

A
  • A haematoma forms around the site of the fracture during the 6-8 hours after injury
  • Bone deprived of nutrients dies and tissue at the site becomes swollen, painful and inflamed
46
Q

Explain what happens during Soft Procallus formation, and how long this process takes?

A
  • Bone reconstruction begins with formation of a soft procallus (fibrocartilaginous callus) which bridges the broken bone ends and splints the bone.
  • Macrophages remove dead bone fragments and then reduce the haematoma
  • This process takes about 2-4 weeks
47
Q

What are soft procallus (fibrocartilaginous callus) consist of?

A
  • Collagen fibres

- Cartilage

48
Q

Explain what happens during Bony Callus formation and how long this process takes

A
  • Osteoblasts convert fibrocartilage into a spongy bone callus
  • This process takes 1-4 months
49
Q

Explain what happens during Bone remodelling

A
  • Spongy bone is replaced by compact bone
  • Removal of excess material from the exterior of the bone and within the bone cavity
  • Fracture line disappears, evidence of the break remains
50
Q

State five factors that could delay bone healing

A
  • 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
51
Q

Explain what happens to bone mass over the lifespan

A
  • From birth to adolescence bone deposit exceeds bone resorption.
  • In females, bone loss begins after age 30. It accelerates greatly after age 45 which is related to reducing oestrogen levels during and following menopause
  • In males, bone loss begins at age 60 as testosterone levels decline after age 55
52
Q

Why is the loss of bone density not effect males as much as females?

A

Since males have a heavier skeleton than females

53
Q

When does bone deposit exceed bone resorption?

A

From birth to adolescence, bone deposit exceeds bone resorption

54
Q

When does bone resorption exceed bone deposit?

A

As we age, bone resorption will exceed bone deposit

55
Q

State the main influence of bone resorption in females

A

Related to reduced oestrogen levels during and following menopause

56
Q

State five factors that determine bone mass

A
  • Genetic Factors
  • Oestrogen levels
  • Exercise
  • Calcium intake and absorption
  • Environmental factors
57
Q

Define osteoporosis

A

Disease in which bone resorption exceeds bone deposit. There is significant loss of bone mass (bone density) and impaired structural integrity of bone

58
Q

State who is most affected by Osteoporosis and explain why

A

Post-menopausal women because the production of oestrogen (also known as estrogen) levels (which protect women from the disease) is decreased.

59
Q

What are Four age related changes of the skeletal system?

A
  • Bone becomes more brittle and prone to fracture
  • Articular cartilages diminish and thins
  • Height is reduced
  • Rigidity of the thoracic cage as costal cartilage ossifies
60
Q

Describe what happens during “Bone becomes more brittle and prone to fracture”?

A
  • Due to reduction in bone mass and density - this results from demineralisation of bone (loss of calcium and other minerals from the extracellular matrix)
  • Reduction in collagen due to decreased synthesis of collagen
61
Q

Describe what happens during “Articular cartilages diminish and thins”?

A

Bones move against one another and lead to rough bony growths (leads to osteoarthritis causing pain and decreased mobility)

62
Q

Describe how “Height is reduced”

A
  • Due to compression of the intervertebral discs (through fluid loss)
  • Due to osteoporosis of the vertebrae
63
Q

Describe what happens during “Rigidity of the thoracic cage as costal cartilage ossifies”

A

Produces shallow breathing resulting in less efficient gas exchange