Bone Tissue + Structure

Question 1

Two extra cellular components of bone:

Answer 1

• Organic
• Inorganic
  (Makes up 98% of bone weight)

Question 2

Organic Extra cellular component: is made up of

Answer 2

33% of bone matrix is organic
- Collagen (protein)
- Ground substance (proteoglycans)
- Function = resists tension ( without collagen the bone is brittle - breaks easily )

Question 3

Inorganic extracellular component

Answer 3

67% of bone matrix is inorganic
- Hydroxyspatite + other calcium minerals (mineral salts)
- Mineral component makes bone hard and resistant to compression

Question 4

Cellular bone component:

Answer 4

Makes up 2% of bone weight
- Osteogenic cells
- Osteoblasts
- Osteocytes
- Osteoclasts
Together these cells maintain bone homeostasis
- balance of bone destruction and formation means amount of bone stays the same

Question 5

What do the 4 cellular bone cells do

Answer 5

Osteogenic cells: stem cells that produce osteoblasts
Osteoblasts: makes, produces new bone
Osteocytes: maintains + communicates - recycle minerals + proteins from matrix - control activity of osteoblasts + Osteoclasts - destroyers - remove bone matrix

Question 6

Two types of bones and how they are related/ different:

Answer 6

• compact = osteon structure
• cancellous = trabecula structure

Made up of the same things (ECM + cells) but structured differently

Question 7

Compact bone macro + microscopically

Answer 7

Microscopically:
- outer surfaces seem dense + impenetrable (periosteum)
- formamina (holes) for blood supply

Microscopically:
- made up of circumferential lamellae and units called osteons

Question 8

Osteon Definition

Answer 8

Longnatudinal (lengthwise) unit within compact bone
- provides a pathway for nutrients to get to cells in ECM

Question 9

Central Canal Definiton

Answer 9

Contains blood vessel and nerves

Question 10

Lamellae

Answer 10

A series of cylinders of ECM formed around a central canal.
- Forms shape of osteon
- Collagen fibres within lamellae resist forces

Question 11

Lacunae

Answer 11

Lakes for osteocytes

Question 12

Canaliculi

Answer 12

Channels for nutrients through ECM

Question 13

Cancellous bone structure

Answer 13

Trabeculae
- Struts of lamella bone
Marrow fills cavities between trabeculae
Osteocytes housed in lacuna in between lamellae/on surface

Question 14

Why trabeculae oriented in certain ways

Answer 14

• Organisation of trabeculae resists force from multiple directions
• Directs force from body weight in single direction down shaft
• Spreads force distally

Question 15

Pelvic girdle force distubution

Answer 15

• trabeculae channel weight areound ilia into femora
• spreading force distally

Question 16

Bone Remodeling

Answer 16

Allow bones to grow - appositional growth
- Osteoblasts add bone matrix in lamellae to bone surface
- Osteoclasts remove bone from medullary cavity

Allows bone to respond plastically
Shape change is possible through life to resist strain

Question 17

Bone homeostasis

Answer 17

Balance of OB and OC activity
Bone is constantly being formed/destroyed
Allows body to mobilise minerals from the bone matrix

Question 18

Name for OC > OB activity

Answer 18

Osteoporosis and osteopina

Question 19

Osteoporosis

Answer 19

• cancellous bone - trabeculae become thinner
• compression fractures of vertebrae

Question 20

Why only some people get osteoporosis

Answer 20

• Women more at risk due to loss of estrogen post-menopause
• Life style factors such as lack of exercise and nutrition factors
• Depends on start point, peak bone mass In 20’s, ideally needs to be high

Question 21

WHAT ARE YOU SACRAFISING

Answer 21

STABILITY OR MOBILITY

Question 22

Is bone dead or living tissue

Answer 22

Living tissue ALIVE

Question 23

Osteocytes vs Osteoblasts which is mature or immature

Answer 23

CYTES is mature

Question 24

3 types of lamellae

Answer 24

Concentric - canal
Interstitial - inbewtween
Circumferential

Question 25

How does the arrangement of blood vessels differ between compact and cancellous bone

Answer 25

• different because of different properties of the bone
• cancellous bone has more surface area with spaces between trabeculaw filled with bone marrow and vessels.
• compact bone is made of osteons tightly packed together so blood vessels are in the central canal of each osteomyelitis,

Question 26

How does the presence of an epiphyseal growth plate relate to linear growth of the long bones?

Answer 26

The growth plate is the place where new bone is added to the ends of the shaft during growth, allowing the bone to grow longer before the epiphysis is fused to it.

Question 27

Why are vertebrae most effected by osteoporosis

Answer 27

vertebrae are particularly susceptible to compression fractures.