Histology of cartilage, bones and joints Flashcards Preview

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Flashcards in Histology of cartilage, bones and joints Deck (41)
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1
Q

What does the ECM of hyaline cartilage consist of?

A

Collagen type II

Aggrecans (large GAGs)

Hyaluronic acid

Chondronectin (glycoprotein)

2
Q

Which is the most common type of cartilage?

A

Hyaline cartilage

3
Q

Which cell type maintains cartilage?

A

Chondrocytes

4
Q

How does elastic cartilage differ from hyaline cartilage?

A

Also contains elastin

5
Q

Describe the properties of elastic cartilage?

A

Flexible

Maintains shape

6
Q

Describe the structure of fibrocartliage?

A

Dense connective tissue

Isolated strands of cartilage

7
Q

Where are each of the three types of cartilage found?

A

Hyaline cartilage: ribs, trachea, joints

Elastic cartilage: ear, ear canals, epiglottis, larynx

Fibrocartilage: menisci, IV discs

8
Q

Describe the structure of compact bone?

A

Outermost: concentric layers

Rest as Haversian systems

9
Q

Describe the structure of trabecular bone?

A

Lamellae

Continuous spaces filled with marrow and blood vessels

10
Q

Where do ostecosyctes lie within the bone?

A

Between trabeculae

11
Q

Describe the contents of the medullary cavity?

A

Bone marrow: red or yellow

Blood vessles include sinusoids instead of capillaries

12
Q

Describe the difference between red and yellow marrow?

A

Red marrow early in life, yellow later

Red marrow mainly haematopoietic cells

Yellow marrow preserves some haematopoietic cells and can become active if needed

13
Q

What is the periosteum?

Where is it found?

A

Thin layer of connective tissue

Covers inner and outer surface of bone

Not where tendon or ligament anchors to bone

Outer fibrous layer (fibroblasts, BVs, collagen)

Inner cellular layer (osteoprogenitor cells)

14
Q

What is the endosteum?

Where is it found?

A

Thin layer of connective tissue

Covers bone lining inner marrow cavity

Not found where a tendon or ligament anchors to bone

15
Q

What are Sharpey’s fibres?

A

Collagen fibres penetrating bone surface

Where tendons and ligaments attach to bone

Bone collagen continuous with collagen of ligament or tendon

16
Q

Describe the blood and nerve supply to bone?

A

Branch in marrow cavity

Shaft and ends supplied separately

Periosteum supplied separately

Nerves follow vessels

17
Q

Describe articular cartilage?

A

Hyaline cartilage

Slippery, smooth, resistant to compression

No perichondrium

18
Q

Describe the contents of the synovial space?

A

Synovial fluid

Lined by synovial membrane

19
Q

Describe the structure of the synovial membrane?

A

Surface layer (intima): 2-3 cells thick, contains fibroblast-like and macrophage-like cells

Sub-intimal layer: fibrous connective tissue

Not an epithelium!

20
Q

Describe why the synovial membrane is not an epithelium?

A

Lacks basement membrane, tight junctions and desmosomes

Very leaky

21
Q

Why is the synovial membrane so leaky?

A

Allos synovial fluid to easily enter joint space

22
Q

What are Haversian systems?

Where are they found?

A

Long, branched, cylindrical columns of bone surrounding a central blood vessel

Found in dense bone

23
Q

Which cells are present in bone?

A

Osteoprogenitor cells

Osteoblasts

Osteocytes

Osteoclasts

24
Q

Where are osteoprogenitor cells found?

A

Periosteum and endosteum

25
Q

Describe the appearance of osteoprogenitor cells?

A

Flattened

26
Q

Describe the purpose of osteoprogenitor cells?

A

Usually quiescent

Can give rise to new osteoblasts

27
Q

Describe the appearance of inactive osteoblasts?

A

Flattened - like osteoprogenitor cells

28
Q

Describe the function of osteoblasts?

A

Make osteoid to make bone

29
Q

Where are osteocytes found?

A

Surrounded by bone

30
Q

Describe the function of osteocytes?

A

Maintain immediate environment around them

Maintain bone in response to loading

Capable of destroying local bone to free calcium

31
Q

Describe the appearance of osteoclasts?

A

Giant multinuclear cells

32
Q

Describe the function of osteoclasts?

A

Seal to bone around edge

Secrete H, CL and proteases to resorb bone

33
Q

Where are osteoclasts derived from?

A

Bone marrow

Related to granulocytes/macrophages

34
Q

Describe the type of bone that is laid down during development?

A

During development, bone is laid down as membrane bone or endochondral bone

Membrane bone: from mesenchyme; skull and flat bones of face, mandibe and clavile

Endochondral bone: weight bearing bones and bones of extremities

35
Q

Describe endochondral bone formation?

A

Cartilage model of bone produced > cartilage destroyed > replaced by bone

36
Q

Describe the process of replacing cartilage with bone?

A

Bone collar forms around diaphysis > cartilage beneath collar degenerates > blood vessles invade > bone cell progenitors arrive > second nucleus of ossification appears at each epiphysis > zones of ossification grow, leave behind growth plate

37
Q

What is the grwoth plate?

A

Thin zone of cartilage

Enables long bones to grow

38
Q

Describe the structure of the growth plate?

A

DISTAL TO PROXIMAL

Normal hyaline cartilage (resting zone)

Dividing chondrocytes (proliferation zone)

Mature chondrocytes (maturation zone)

Hypertrophic/dying chondrocytes (hypertrophic zone)

Ossification

39
Q

What is woven bone?

Describe its structure?

A

New bone that appears during development or repair

More cellular, more collagen, no Haversian systems

Soon remodelled

40
Q

Describe the process of remodelling bone?

A

Osteoclasts form cavities in bone, that are the size and shape of Haversian systems and appear along the stress axis of bone

Blood vessels and endosteum invade

Osteoblasts lay layers of bone with collagen alternating in direction

Final layer leaves narrow space around blood vessel (Haversian canal)

41
Q

What is a Haversian canal?

A

Narrow space between final layer of bone and blood vessel in a Haversian system