Bone Flashcards

1
Q

What is immature bone?

A

Bone with osteocytes fairly randomly arranged

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2
Q

What is mature bone?

A

Bone with osteocytes arranged in concentric lamellae of osteons

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3
Q

What is an osteon?

A

Cylindrical concentric layers of compact bone which surround haversian canal

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4
Q

How does bone differ from cartilage?

A

It’s vascular

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5
Q

Give three characteristics of bone

A

Can withstand stress, Responds to stress and strains via growth, Sensitive to pain, Contains cells, fibres and ground substance

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6
Q

Give four functions of bone

A

SupportProtectionMineral storageHaemopoieses

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7
Q

What are two forms of bone?

A

Compact and spongelike (dense and cancellous)

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8
Q

What is haemopoiesis?

A

Formation of blood cellular components

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9
Q

What is the structure of compact bone?

A

Osteons with central haversian canal, which communicate via volkmanns canals

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10
Q

What is a haversian canal?

A

A neurovascular canal

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11
Q

How do osteocytes connect to each other?

A

Caliculi

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12
Q

What is spongy bone? (also known as cancellous and medullar bone)

A

Meshwork of trabeculae filled in with marrow

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13
Q

Two different types of marrow?

A

Red - Red blood cell synthesisYellow - Adipose tissue

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14
Q

What is marrow cavity lined with?

A

Endosteum

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15
Q

What is endosteum?

A

Thin layer of connective tisswue which lines the medullarly cavity

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16
Q

Where is the epiphysis of the bone?

A

The head

17
Q

What percentage of bone matrix is inorganic?

A

65%

18
Q

Name two inorganic salts found in bone matrix

A

matrix Calcium phosphate and Calcium Carbonate

19
Q

Where does bones hardness and rigidity come from?

A

Interaction between inorganic salts and collagen

20
Q

Where does bones flexibility come from?

A

Collagen fibres

21
Q

Where are Calcium and Phosphate stored in bone?

A

In the extracellular matrix

22
Q

What four things are calcium required for in the body?

A

Muscle contraction, blood coagulation, cell membrane permeability and nerve impulse transmission

23
Q

What does PTH do?

A

Stimulates osteoclasts to reabsorb bone matrix, releasing calcium into blood

24
Q

What happens when blood calcium levels higher than normal?

A

Calcitonin released, which inhibits osteoclast realse and decreases bone reabsorption

25
Q

What are the three bone cell types found in bone?

A

Osteoblasts, Osteoclasts and Osteocytes

26
Q

What is the function of osteoblasts?

A

Synthesise organic components of cells, making bone and produce the osteoid matrix.

27
Q

What are osteocytes?

A

What are osteocytes?

28
Q

How are osteocytes formed?

A

When osteoblasts are entombed to produce osteocytes.

29
Q

What are osteoclasts?

A

Large multinucleated cells from monocytes which digest bone

30
Q

What is periosteum and what is it made up of?

A

Two layers, connected by Sharpeys fibres. One dense collagenic outer layer, the other is more loosely arranged containing osteogenic cells and is referred to as osteogenic layer.

31
Q

Describe primary microstructure of bone, and give another name for it

A

Immature boneFirst bone to appear in the development and repair, it’s then replaced by mature boneCollagen fibres arranged in a random, interwoven fashionMore cells and less minerals

32
Q

Secondary microstructure of bone

A

Compact dense cortical boneSeries of Haversian Systems (osteons): consisting of concentric lamellae of bone laid around a central canal containing blood vessels.The spaces between Haversian systems are filled with bony lamellae (interstitial lamellae)The outer surface has extended lamellae (circumferential)Sponge-like cancellous medullaryBone, which is always surrounded by compact bone.It forms the meshwork of bone plates or trabeculae then the spaces are filled with marrow

33
Q

Give two ways in which bone develops

A

endochondral ossificationintramembranous ossification.

34
Q

Outline endochondral ossification

A

Cartilage is reabsorbed and replaced with bone (e.g. long bones)Begins at the primary centre in the shaft (diaphysis) and later at each end (epiphysis – secondary centre)Growth in length is at epiphyseal growth plates

35
Q

Outline intramembranous ossification

A

The bone begins as highly vascularised loose connective tissue.Mesenchymal cells differentiate  osteoblasts surrounded by collagen fibres and ground substance.They secrete uncalcified matrix (osteoid) and then become osteocytes

36
Q

How does bone remodel?

A

through the actions of osteoclasts and osteoblasts releasing and incorporating calcium into and from the matrix.

37
Q

Outline process of fracture repair

A

Break –> Haematoma –> Osteo Callus –> Primary Bone –> Secondary Bone1.Bone breaks2.Bone matrix is destroyed and the bone cells adjoining the fracture will die3.Inflammatory cells invade and form a pre-callus which contains a blood clot (haematoma) and fibrous tissue(If the periosteum is still intact a pro-callus is formed when the area is invaded by osteoclasts and macrophages which is more fibrous)4.An osteocallus of primary bone is made which is then calcified to secondary5.The bone is pulled and pressured to match the contours of the surrounding bone (mainly via tendons) and eventually forms mature bone6.Bone heals without forming a scar

38
Q

What are the zones in an epiphyseal growth plate?

A

Reserved cartilageProliferationHypertrophy Calcified cartilage Resorption

39
Q

Outline what happens in each zone of the epiphyseal growth plate.

A

Reserved cartilage – no cell proliferation/matrix productionProliferation – cells enlarge, divide to form columns and secrete matrixHypertrophy – enlarge greatly, matrix composed between columnsCalcified cartilage – cells degenerate, matrix calcifiedResorption – matrix in direct contact w/ marrow cavity. Small blood vessels and connective tissue invade region of dying chondrocytes which leave calcified spicules. Bone is laid down on spicules