Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MBBS II MSS > L19 - Bone Structure and Remodelling > Flashcards

L19 - Bone Structure and Remodelling Flashcards

1
Q

What are the 2 divisions of the skeletal system?

A
  1. Axial skeleton

2. Appendicular skeleton

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What bones belong to axial skeleton?

A

axial skeleton: skull bones, auditory ossicles, hyoid bone, ribs, breastbone and bones of the back

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What bones belong to appendicular skeleton?

A

bones of the upper and lower limbs, pectoral girdle and pelvic girdle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the 5 types of bones?

A

Long bones Short bones Flat bones Irregular bones Sesamoid bones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

List 5 functions of Bone?

A
  • Support
  • Protect viscera
  • Muscle attachment for locomotion of limbs
  • Reservoir of calcium and phosphate for bone remodelling, electrolyte balance
  • Bone marrow for haematopoiesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Compare the matrix in bone and cartilage?

A

Bone: Inorganic calcified hydroxyapatite crystal + Organic collagen type I with proteoglycan and gylcoproteins

Cartilage: Non-calcified + Collagen type II hyaline cartilage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Compare the mechanical properties of bone and cartilage?

A

Bone = hard

Cartilage = resilient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Compare the vasculature in bone vs cartilage?

A 
Bone = highly vascularized 
Cartilage = Avascular
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Compare the growth mode in bone vs cartilage?

A

Bone = appositional growth from periosteum and endosteum (layer by layer because calcified matrix is inexpandible)

Cartilage = Appositional and Interstitial growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Name the three bone cells?

A

Osteoblast

Osteocyte

Osteoclast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Source of osteoblasts?

A

OSTEOBLAST = osteoprogenitor cells derived from mesenchymal stem cell in the highly vascularized PERIOSTEUM/ ENDOSTEUM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Source of Osteoclasts?

A

derived from fusion of circulating monocytes (mononuclear phagocyte system)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Function of Osteoblasts?

A

Lines all bone surfaces to form bone:

  • Synthesize organic matrix protein (osteoid) around itself. Once surrounded by newly made matrix = osteocytes
  • Produce calcium and phosphate minerals for osteoid calcification (inorganic component of matrix)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Half life and location of osteocytes?

A

Average half life = 25 years

Location = Inside bone matrix in lacunae (trapped just below the bone surface by the bony matrix it produced)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Function of osteocytes?

A

maintenance of bony matrix&raquo_space; Osteolytic Osteolysis

– contact with adjacent osteocytes by thin cytoplasm located in canaliculi for nutrition and communication (e.g. resorb dead bone)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Location and Function of osteoclasts?

A

Location = Lie within depression of bone surfaces (Howship’s Lacunae)

Function: secrete acid, collagenase and proteolytic enzymes to resorb bony matrix at endosteum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the different forms of osteoblasts?

A

2) Active stage -cuboidal to columnar shape, basophilic cytoplasm, high alkaline phosphatase activity
2) Inactive stage –flatten lining cells, low alkaline phosphatase activity (for protection of bone surface)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

List 5 histological features of Osteoclasts?

A

1) Large
2) Multinucleated
3) Acidophilic cytoplasm (lots of lyzosomes)
4) Ruffled border (increases surface area of resorption)
5) Clear zone (resorption compartment: region of cytoplasm that surrounds the ruffled border to isolate region of osteolysis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

List 3 functions of Periosteum and endosteum?

A

1) Line all surfaces of bone (exposed bony surface will be resorbed by osteoclasts)
2) Provide supply of osteoblasts (appositional growth)
3) Highly vascularized = provide nutrition to bone cells (important for growth, remodeling and repairing of bone)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Describe the structure of periosteum?

A

Outer layer = collagen fibers and fibroblasts (irregular dense connective tissue)

Inner layer = osteoprogenitor cells for differentiation in osteoblasts for appositional growth

Sharpey’s fibers anchor the periosteum to bone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Describe the structure of endosteum?

A
  • Covering the “internal surface” of the bone
  • Lining the marrow cavity
  • Osteoprogenitor cells differentiate into osteoblasts: appositional growth
  • Exposed regions eaten by osteoclasts
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the types of bones according to morphology?

A

Long bones (width < length), e.g. humerus

Short bones, e.g. trapezoid (wrist bone)

Flat bones, e.g. sternum

Irregular bones, e.g. vertebra

Sesamoid bones, e.g. patella

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the types of bones according to the arrangement of collagen fibers?

A

Primary = immature/ woven bone with random disposition of collagen

Secondary = mature bone with organized concentric lamellar deposition of collagen

Primary bone (embryo, during repair) will be replaced by secondary bone)

24
Q

What are the types of bones according to gross structure in cross section?

A

1) Compact bone/ Cortical bone = exterior, no cavities

2) Cancellous bone/ Spongy bone = interior, intercommunicating marrow cavities

25
Q

Describe the structure of Compact bone?

A

Anatomical and functional unit = Osteon (Haversian system)

  • Concentric lamellae of bone surrounds Haversian canal (contains BV, nerves, lymph., loose connective tissue)
  • Communicate with other Harversian systems and with marrow through Transverse Volkmann’s Canals
  • Brings nutrition to osteocytes through canaliculi
26
Q

Osteoporosis weaken which part of the bone first and why?

A

Cancellous bone

Lighter and more porous than compact bone, cancellous bone provides more surface area for bone remodeling and is more metabolically active

27
Q

Why are Osteons in compact/ cortical bone overlapping in pattern?

A

because of the continuous process of bone remodeling

28
Q

Describe the structure of spongy bone/ cancellous bone?

A
  • anatomical and functional unit = TRABECULA (not Osteon as in cortical bone)
  • Anastomosing bony spicules form a meshwork of intercommunicating spaces
  • Highly vascular and hosting red bone marrow
29
Q

List some differences between cancellous bone and cortical bone?

A

Cancellous bone is weaker, more flexible, large SA/ more porous, higher metabolic activity

30
Q

What are the types of Osteogenesis?

A

According to the origins of development

1) Intramembranous–most flat bones
2) Endochrondral–most long bones

No major difference in histological structure!! Both end up with bone remodelling and appositional growth

31
Q

Describe the osteogenesis of FLAT bones? * Where does it take place, what happens?

A

Intramembranous ossification

Takes place within condensation of mesenchymal tissue:

DIRECT DIFFERENTIATION of mesenchymal cells into osteoblasts to synthesize AND mineralize bone matrix&raquo_space; become osteocytes

Surrounding connective tissue becomes periosteum

No intermediate stage of cartilage, thickens by appositional growth

32
Q

Where does osteogenesis of LONG and SHORT bones take place?

A

Endochondral ossification

Takes place within a piece of pre-existing cartilaginous tissue

Cartilage acts as scaffold, later replaced by bone

Within cartilaginous tissue:
1) Primary ossification center in the center of diaphysis (appear from 4 weeks embryo)

2) Secondary ossification center in epiphysis of long bones (appear after birth until 5 years old)

33
Q

What are the ossification centers in endochondral ossification?

A

1) Primary ossification center in the center of diaphysis (appear from 4 weeks embryo)
2) Secondary ossification center in epiphysis of long bones (appear after birth until 5 years old)

34
Q

What are the 7 steps in endochondral ossification?

A

1) Proliferation of cartilage cells and hypertrophy of chondrocytes (to lay down cartilage scaffold)
2) Death of chondrocytes and calcification of cartilage scaffold
3) Resorption of cartilage by osteoclasts from surrounding periosteum
4) Invasion of osteogenic bud (osteoblasts and blood vessels) from periosteum
5) Osteoblasts mature into osteocytes
6) Synthesis of new bone matrix onto surface of calcified cartilage
7) Re modelling to replace immature bone with mature bone

35
Q

What are the 6 steps in Intermembranous ossification?

A

1) Groups of mesenchymal cells from periosteum differentiate directly into osteoblasts
2) New bone matrix made and mineralized by osteoblasts
3) Osteoblasts mature to osteocytes
4) Surrounding connective tissue becomes periosterum of new bone
5) Replacement of immature bone with mature bone
6) Thickening by appositional growth

36
Q

What are the 5 zones of epiphyseal growth plate at epiphysis (ends) of long bones?

A

Resting zone: resting hyaline cartilage

Proliferative zone :cartilage cells divide rapidly into stacks

Hypertrophic cartilage zone: condrocytes hypertrophy

Calcified cartilage zone: chondrocytes die, cartilage calcification

Ossification resorption zone: cartilage replaced by bone by osteoblasts from osteogenic bud

37
Q

Define bone remodeling?

A

constant lifelong process involving both bone resorption, bone formation

to adjust bone architecture, repair fractures and micro-damage

38
Q

Apart from maintenance of bone health, what is another function of bone remodeling?

A

Important in maintaining plasma calcium homeostasis

39
Q

What are the 4 endogenous compounds that can affect bone remodeling?

A
  • Growth hormone/IGF-1
  • Calcitonin
  • Estrogen or testosterone
  • Parathyroid hormone (PTH)
40
Q

What is the effect of growth hormone/ IGF -1 on bone remodeling?

A

Increase chondrocyte & osteoblasts proliferation

Increase bone synthesis

41
Q

What is the effect of Calcitonin on bone remodeling?

A

↓ osteoclast activity, Ca2+ level & bone resorption

Maintain bone, less breakdown

42
Q

What is the effect of estrogen and testosterone on bone remodeling?

A

Decrease resorption, Increase formation

43
Q

What is the effect of Parathyroid hormone (PTH) on bone remodeling?

A

Increase bone resorption and calcium levels

Increase calcium absorption in small intestines and kidney

44
Q

What are the 3 stages in bone repair?

A

1) Inflammatory phase
2) Reparative stage
3) Remodeling stage

45
Q

What occurs in the inflammatory phase of bone repair?

A

Inflammatory cells, fibroblasts infiltrate the bone

Haematoma formation

Form granulation tissue, vascular tissue grows in, mesenchymal cells migrate

46
Q

What can hinder the inflammatory phase of bone repair?

A

NSAIDs

Smoking

47
Q

What occurs in the reparative phase of bone repair?

A

Form Fibrous and Cartilagous callus for fibrous connection between fractured ends, surrounding periosteum provide BV

Form woven bone, endochondral ossification

48
Q

What can hinder the reparative phase of bone repair?

A

Movement at this stage may damage soft callus&raquo_space; need braces

49
Q

What occurs in the remodeling phase of bone repair?

A

Remodel to original bone shape and strength

50
Q

What is the effect of menopause on bone healing

A

Reduction of gonadal hormones - estrogen

Cannot decrease resoprtion and increase synthesis of new bone

Bone fracture may never heal

51
Q

What are the 3 types of cartilage?

A

Hyaline cartilage

Elastic cartilage

Fibrocartilage

52
Q

List some locations of hyaline cartilage?

A

 Epiphyseal plate: essential for longitudinal growth of long bone

 Articular cartilage at joints

 Walls of respiratory passages

53
Q

Where is elastic cartilage found?

A

auricle of the ear, walls of the external auditory canals, auditory tubes, epiglottis, cuneiform cartilage of the larynx

54
Q

Where is fibrocartilage found?

A

intervertebral discs, ligament attachment to cartilaginous surface of bone, symphysis pubis

55
Q

What is the structure of fibrocartilage?

A
  • Chondrocytes often arranged in long rows (in lacunae)
  • Type I collagen fibres aligned in parallel along chondrocytes
  • Less amorphous matrix
  • No identifiable perichondrium

MBBS II MSS (31 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions