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Musculoskeletal System > Histo > Flashcards

Histo Flashcards

1
Q

What are the 3 types of connective tissue?

A

1) Loose

Dense:
2) Dense regular
3) Dense irregular

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2
Q

What are 2 examples of regular dense connective tissues?

A

1) Tendon
2) Ligaments

  • parallel and dense arrangement of Type 1 collagen fibres provide tensile strength and strong resistance to forces
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3
Q

What are 4 functions of cartilage?

A

1) Smooth articular surfaces at bony ends
2) Shock absorber
3) Structural support (eg. ear, trachea)
4) New bone formation

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4
Q

What are chondrocytes?

A

Cells with secrete collagen II fibres and ground substance.

  • basophillic cytoplasm, RER, golgi vesicles
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5
Q

Describe the formation of chondrocytes.

A

Stellate shaped primitive mesenchymal cells
→ differentiate → rounded chondroblasts
→ divide → chondrocytes

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6
Q

What are 3 components of ground substance?

A

1) Proteoglycans (aggrecans)
- provides resilience
2) Sulphated glycosaminoglycans (chondroitin sulfate, keratin sulphate)
- provides firmness
3) Hyaluronic acid

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7
Q

Which substance in the matrix accounts for its weight bearing capacity?

A

Hyaluronic acid

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8
Q

Hyaline cartilage is composed of type __ collagen fibrils. It contains (cells (1)) and (subtances (3)). The matrix is mainly made of _____________ which provides resilience.

A

Hyaline cartilage:
- Type 2 collagen
- chondrocytes in lacunae in cartilage matrix
- sulfated proteoglycans, non-collagenous proteins, glycoproteins
- 60-80% water → resilience

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9
Q

True or false: Hyaline cartilage is highly vascularised to ensure the efficient clearance of waste products and avoid joint injury.

A

False.
Cartilage is avascular
- receives nourishment by diffusion through water in ground substance

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10
Q

What are 3 examples of hyaline cartilage and their respective functions?

A

1) Articular ends of bone
- provides low friction surface
- distributes applied force to underlying bone

2) Costal cartilage
- lubrication for synovial joints

3) Epiphyseal growth plate
- new bone formation

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11
Q

Where do cartilage/chondrocytes arise from? (where are the mesenchymal cell located?)

A

Perichondrium

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12
Q

What is the perichondrium?

A

Firmly attached connective tissue surrounding hyaline cartilage
i) inner cellular (chondrogenic) → source of new cartilage cells
ii) outer fibrous layer → dense irregular fibrous connective tissue

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13
Q

Which layer of the perichondrium is lacking in adult cartilage?

A

Inner cellular/chondrogenic layer
- only outer fibrous left

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14
Q

What are 3 exceptions where perichondrium are not seen surrounding hyaline cartilage?

A

1) Articular ends of joints
2) Sites of bone formation (epiphyseal plate)
3) Nasal and costal cartilages

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15
Q

What is the main implication of not articular cartilage not having a perichondrium?

A

Cannot repair when there is damage

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16
Q

What are the 2 forms of cartilage growth?

A

1) Appositional
- ↑ in diameter
- new cartilage develops at surface of existing cartilage

2) Interstitial
- ↑ in length
- within existing cartilage by division of chondrocytes

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17
Q

When does hyaline cartilage calcify?

A

At articular cartilage
1) During endochondral ossification
2) Aging

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18
Q

What are 3 reasons for why repair of cartilage is generally poor?

A

1) Avascularity of cartilage

2) Immobility of chondrocytes

3) Limited proliferation of mature chondrocytes

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19
Q

True or false. Elastic cartilage can be seen on a typical HnE stain?

A

False.
Special stains (Resorcin fuschin and orcein stains) needed to show elastic fibres

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20
Q

What are 4 examples of elastic cartilage?

A

1) External ear/pinna
2) External auditory canal
3) Eustachian tube
4) Epiglottis of larynx, apex of arytenoid/corniculate/cuneiform cartilage

21
Q

What are 2 functions of fibrocartilage?

A

1) Absorb shock
2) Resist compression and shearing forces

22
Q

Fibrocartilage:
- (thick/thin) collagen fibres w white fibrocartilage
- abundant type __ collagen, some type ___
- (has/lacks) perichondrium

A

Fibrocartilage:
- thick collagen fibres w white fibrocartilage
- abundant type II collagen, some type I
- lacks perichondrium

23
Q

What are 4 examples of fibrocartilage?

A

1) Intervertebral disc
2) Pubis symphysis
3) Manubriosternal joint
4) Menisci of knee joint
5) Glenoid labrum
6) Acetabular labrum
7) Temporomandibular joint
8) Sternoclavicular joint

24
Q

What are 3 structural components of a long bone?

A

1) Epiphysis (end)
2) Diaphysis (shaft)
3) Metaphysis/growth plate in children

25
Q

What are 2 layers of periosteum?

A

1) Fibrous outer
2) Osteogenic inner

26
Q

The marrow cavity holds ______ bones narrow with has ____________ lining.

A

Marrow cavity:
red/yellow marrow
endosteum lining

27
Q

What are the 2 types of bone?

A

1) Compact bone
- outer layer of bones/shaft
- almost no space between layers of bone tissue

2) Spongy/cancellous bone
- interior of bones
- marrow cavities between trabeculae

28
Q

What are the 2 forms of marrow cavity?

A

1) Red
- hematopoietic
- in flat, irregular bones and ends of adult femur, humerus

2) Yellow
- fat
- may re-differentiate into red marrow under stress

29
Q

What are the organic and inorganic components of bone?

A

Organic: 1/3
- cells
- Type 1 collagen
- Ground substance

Inorganic: 2/3
- Calcium phosphate
- Hydroxyapatite crystals

30
Q

What are 3 bone cells?

A

1) Osteoblasts
- form bone matrix

2) Osteocytes
- mechanosensors (detect (i) mechanical load (ii) stress (iii) fatigue-induced microdamage) → trigger remedial response from osteoblasts and osteoclasts

3) Osteoclasts
- large mobile multi-nucleated cells
- needed for matrix resorption during bone growth and remodeling (contains lysosomes)
- ruffled border releases acid phosphatases

31
Q

What cells do osteocytes arise from?

A

Osteoprogenitor → Osteoblast → Osteocyte

32
Q

Where are osteoprogenitor cells found?

A

1) Inner cellular layer of periosteum and endosteum

2) Walls of haverisian and volkman’s canals

33
Q

What is the histological appearance of osteoblasts?

A

Cuboidal/polygonal cells
- oval nucleus and basophilic cytoplasm
- newly formed bone surface

34
Q

How are fibrous/immature/woven bones differentiated from lamellar/mature bones?

A

Fibrous/immature/woven bones:
- seen in embryonic life and fracture healing

Lamellar/mature bones:
- secondary bones
- lamellar pattern of fibre arrangement

35
Q

What are the components of the Osteon (Haversian) system?

A

1) Central canal

2) Concentric lamellae

3) Osteocytes

4) Canaliculi

5) Perforating canals
- contain neurovascular bundles & run perpendicular to central canals to connect them

6) Circumferential lamellae
i) External (internal → periosteum)
ii) Internal (internal → endosteum)

7) Interstitial lamellae

36
Q

What are Sharpey’s fibres?

A

At sites of attachement (to ligaments/tendons), Collagen fibres in periosteum that are arranged obliquely or perpendicular to bony surface continuous with ECM

(collagen is usually parallel to surface in periosteum)

37
Q

What is the characterisitic of trabecular bone?

A

Lack of osteons

38
Q

What are the 2 types of ossification?

A

1) Intramembranous
- mesenchymal (fibrous membranes) → bone
- flat bones
- begins in-utero wk8

2) Endochondral
- Mesenchyme → cartilage → bone

39
Q

Describe the process of intramembranous ossification.

A

1) Mesenchymal cells group into clusters → ossification centers

2) Secreted osteoid traps osteoblasts → osteocytes

3) Trabecular matrix and periosteum form

4) Compact bone develops superficial to the trabecular bone and crowded blood vessels condense into red marrow

40
Q

Describe the process of endochondral ossification.

A

1) Fetal hyaline cartilage model develops

2) Cartilage calcifies, periosteal bone collar forms arnd diaphysis

3) 1° ossification center forms in diaphysis

4) 2­­° ossification center forms in epiphyses

5) Bone replace cartilage, except articular cartilage and epiphyseal plates

6) Epiphyseal plates ossify → epiphyseal lines

41
Q

Epiphyseal plate zones: (superficial to deep)
Reserved cartilage → ________
Proliferating cells → __________
Hypertrophy → _____________
Calcified cartilage → _________
Resorption/ossification → _______________

A

Epiphyseal plate zones:
Reserved cartilage → small resting cells

Proliferating cells → larger dividing cells

Hypertrophy → large chondrocytes in columns

Calcified cartilage → calcified matrix, chondrocyte apoptosis

Resorption/ossification → removal of calcified cartilage, deposition of new bone

42
Q

Of the liver enzymes,
↑Osteoblast activity → ↑_______
↑Osteoclast activity → ↑__________

A

↑Osteoblast activity → ↑alkaline phosphatase

↑Osteoclast activity → ↑acid phosphatase

43
Q

What are the 2 forms of bone growth and where do they occur?

A

1) Interstitial (length-wise)
- in epiphyseal plate
- chondrocytes undergo mitosis

2) Appositional growth (diameter/thickness)
- within periosteum

44
Q

Describe the process of fracture repair?

A

1) Hematoma formation
- mass of clotted blood

2) Callus formation
- “Soft callus” (cartilaginous) splint

3) Bony callus formation
- “hard callus” (spongy bone)

4) Bone remodelling
- spongy bone of hard callus replaced with compact bone

45
Q

What are the hormones that affect bone homeostasis?

A

1) Thyroid → stimulate osteoblasts → ↑growth

2) Calcitonin → inhibit osteoclast → ↓breakdown

3) PTH → stimulate osteoclast → ↑breakdown

4) Androgens → stimulate osteoblasts → ↑bone formation

5) GH → Somatomedin → growth of cartilage @ epiphyseal plate

46
Q

What is osteopetrosis?

A

↓osteoclastic activity

47
Q

What is osteoporosis?

A

Bone resorption&raquo_space;» Bone formation

48
Q

What is osteogenesis imperfecta?

A

Inadequate osteoblastic activity → inhibit deposition process in osteons

49
Q

What is Paget’s osteitis deformans?

A

Remodelling activity greatly accelerated (both osteoblasts and osteoclasts are active)

Musculoskeletal System (22 decks)

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