Development and growth of bone Flashcards

1
Q

What are some of the functions of bone?

A
Support of the body shape 
Systems of levers for muscle action 
Protection of internal organs 
Site of blood cell formation 
Mineral storage pool
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2
Q

What are the two mechanical properties of bone and what is responsible for these properties?

A

FLEXIBILITY (like a cable), due to the protein element of bone– and resistance to tension because the framework is collagen and other bone proteins (osteoid)

Pillar-like STIFFNESS, due to minerals– and resistance to compression conferred by impregnation of collagen with crystalline mineral (hydroxyapatite – a complex calcium hydroxyphosphate)

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3
Q

What are the two main types of bone tissue?

A

Woven (immature)

Lamellar (mature)

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4
Q

When is woven bone found in adults?

A

It is only found in repairing fractures

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5
Q

What is the technical term for the shaft of a bone?

A

Diaphysis

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6
Q

What is the technical term for the head of a bone?

A

Epiphysis

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7
Q

What type of bone is found around the outside of the bone?

A

Compact bone (aka cortical bone)

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8
Q

What is the term given to the cavity within the bone?

A

Medullary cavity (contains bone marrow)

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9
Q

What type of bone is found within this cavity?

A

Trabecular/spongy/cancellous bone (this is still lamellar bone)

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10
Q

What units are the outer compact/cortical bone arranged into? (in lamellar/mature bone)

A

Osteons/Haversian Systems
They have a central canal containing vessels and around the vessels you have concentric layers of bone maintained by concentrically arranged osteocytes

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11
Q

In what planes are these units arranged?

A

They are usually organised along pressure planes

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12
Q

What provides the main blood supply to the bone marrow?

A

Nutrient artery (passing through the nutrient foramen)

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13
Q

What are the two layers of the periosteum?

A

Fibrous (outer)
Cellular (inner)

The fibrous layer contains fibroblasts, while the cellular layer contains progenitor cells that develop into osteoblasts. These osteoblasts are responsible for increasing the width of a long bone and the overall size of the other bone types.

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14
Q

What are the main roles of the periosteum? Does it have a blood and nerve supply?

A

Bone growth and repair

It is vascular
It has a good sensory nerve supply

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15
Q

What do osteogenic cells give rise to?

A

Osteogenic cells (initial stem cells) –> Osteoblasts –> Osteocytes slide 17

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16
Q

What lineage do osteoclasts come from?

A

They are derived from the immune cell lineage – they are modified macrophages

17
Q

At what point in fetal life does the skeleton start to develop?

A

6 weeks

18
Q

What are the two types of ossification?

A
Intramembranous 
Endochondral (within cartilage)
19
Q

Describe intramembranous ossification.

A

Occurs within existing vascular connective tissue
Bone matrix (ostein) is deposited around the collagen
This mineralises to form woven bone
It then remodels to form lamellar bone

20
Q

Describe endochondral ossification.

A

Occurs within existing fetal cartilage models
Cartilage calcifies and the chondrocytes die
Periosteal osteoclasts cut channels for sprouting vessels
Osteoblasts enter with the vessels to build bone around them

21
Q

List some bones in which intramembranous ossification takes place.

A

Skull bones
Jaw bones (mandible)
Part of the clavicle

22
Q

At what point do the epiphyses ossify in a child’s wrist?

A

2 years

23
Q

Until what point do epiphyseal plates remain cartilaginous?

A

Until you stop growing (ie your bones stop growing) – then the epiphyseal plates will calcify. The epiphyseal plate is where your bone grows and helps the bone to lengthen.