12 - Cartilage and Bone Flashcards Preview

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Flashcards in 12 - Cartilage and Bone Deck (37)
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1
Q

What is cartilage?

A

Avascular connective tissue that consists of chrondocytes and a semisolid extracellular matrix

2
Q

What are the three types of cartilage and what are their extracellular matrixes made of?

A

All matrix have proteoglycan and hyaluronic acid

- Hyaline: Type II Collagen aggregates to 100 hyaluronate proteoglycan

- Elastic: Elastic fibres and elastic lamellar

- Fibrocartilage (Fibrous): Mainly Type I collagen

3
Q

Where is hyaline cartilage found?

A
  • Trachea
  • Layrnx
  • Articular at joints
  • Nose
  • Costal cartilage
  • Epiphyseal growth plates
  • Foetus
4
Q

What is the structure and function of hyaline cartilage?

A

Structure:

  • Avascular
  • Perichondrium on edges.
  • Perichondrocytes differentiate into chondroblasts then chondrocytes, which sit in lacuna.
  • Isogenous groups.
  • Chondrocytes separate as they release extracellular matrix.

Function:

  • Xcell matrix is full of water. Water non-compressible so resilient to increased loads.
5
Q

What is the function of cartilage?

A
  • Resilient
  • Firm
  • Flexible
  • Strength

Fibres, Water and Ground substance make up xcellular matrix that give cartilage it’s properties. Allows Articular joints to slide over each other

6
Q

How does cartilage get nutrients?

A

Cartilage avascular. Nutrients have to diffuse from vessels in the perichondrium to the extracellular matrix.

7
Q

What is a proteoglycan?

A

Make up ground substance. Core protein with GAG covalently bound.

8
Q

What is GAG?

A

Glycosaminoglycans. Long chained poly-saccharides. They attract water to form hydrated gel that permits rapid diffusion but resists compression

9
Q

What GAG is predominantly found in cartilage?

A

Hyaluronate. Binds to core protein to form proteoglycan that is massively hydrophilic, attracts water to form gel.

10
Q

Why is the extracellular matrix of cartilage more gel-like than other connective tissues?

A

Contains more proteoglycan so in ground substance

11
Q

What cartilage is present in the trachea and why?

A

Hyaline (below submucosa). Reinforces trachea to protect and maintain airway

12
Q

When does cartilage repair itself?

A

It doesn’t, chondrocytes cannot divide. Fibroblasts replace cartilage with fibrous scar tissue

13
Q

Where is elastic cartilage found?

A
  • Pinna of ear
  • Eustachian tube (inner ear to oral)
  • Epiglottis
14
Q

What is the function of the elastic cartilage?

A

Areas that need extra flexibility and support

15
Q

What is the structure of elastic cartilage?

A

Perichondrium containing fibroblasts. Lots of chondrocytes surrounded by dense elastin fibres. ‘Gaps’ where chondrocytes have laid down their elastic and died.

16
Q

Where is fibrocartilage found?

A
  • Pubic symphysis
  • Intervertebral disc
  • Knee menisci (padlike cartilage)
  • Articular joint of sterniclavicular and temporomandibular
17
Q

What is the function of fibrocartilage?

A

Found in areas of directional stress, so shock absorbs and resists shearing forces.

18
Q

What is the structure of fibrocartilage?

A
  • Few chondrocytes and few fibroblasts arranged in rows, in collagen. No surrounding perichondrium.
  • Mix of hyaline cartilage and dense regular connective tissue
19
Q

What two tissues can fibrocartilage be called a mixture of?

A

Hyaline cartilage and dense regular

20
Q

How do bones develop in the fetus in simple terms?

A

Hyaline cartilage model mineralises to form bone and then grows by endochondral ossification

21
Q

What cartilage is at bone ends?

A

Hyaline Articular with no perichondrium. Nutrients come from synovial fluid.

22
Q

Is bone inert?

A

No it is dynamic, constantly being broken down and remodelled

23
Q

What is compact bone made of?

A

Concentrically arranged lamella. Osteons.

24
Q

What is cancellous bones made up of?

A

Trabeculae. Lamellae woven together

25
Q

Which bones have a greater proportion of spongy bone?

A

Short

26
Q

What is appositional bone growth?

A
  • Bone remodelling
  • Growth in width
  • Bone taken from endosteum and added to periosteum
27
Q

What is interstitial growth?

A
  • Growth from the centre.
  • Increase in bone length.
28
Q

What is the periosteum?

A

Dense irregular connective tissue, connected to the outside of bone by collagen fibres called Sharpey fibres.

- 1st layer - dense collagenous with nerves, fibroblasts and vessels

- 2nd layer - Osteogenic cells, less vascular

CONTAINS NERVES, LYMPH AND BLOOD VESSELS

29
Q

What is perichondrium?

A

Dense irregular connective tissue covering hyaline and elastic cartilage. It is vascular and supplies the cartilage chondrocytes with nutrients. Contains chrondroblasts

30
Q

What is the endosteum?

A

Thin connective tissue layer that lines marrow cavity. Dense irregular. Contains osteopregenitor cells

31
Q

Where is the periosteum present?

A

Covering every bone, bar the patella and phalanges, and disappears at articular surfaces

32
Q

What is the structure of compact bone?

A
  • Osteons run parallel to long axis
  • Haversian canal at the middle (containing lymph, vessels, nerve), surrounded by concentric lamellae
  • Lacuna in osteon containing osteocytes. Form canniculi with one another and haversian for nutrients
  • Haversion’s and spongy bone joined by Volkmann’s canal
  • Collagen in each lacuna run in different directions for high torsion strength
33
Q

What is an:

  • Osteoblast
  • Osteocyte
  • Osteoclast ?
A

Osteoblast: Intermediate cell on endosteum that cannot divide. Lays down osteoid

Osteoclast: Large WBC on endosteum that undergoes resorption of bone, remodelling it. Not in bone itself

Osteocyte: Terminally differentiated cell when osteoblast trapped in osteoid. No longer lays down matrix just maintains tissue.

Osteogenic Cell —> Osteoblast —> Osteocyte

34
Q

What are the inorganic and organic components of bone matrix and their function?

A

Inorganic - 65%.

Calcium, Phosphate, Mg and Al Salts

Resist bending and compressing

Organic - 35%.

Collagen 1, GAGs, proteins like osteocalcin and osteonectin.

Resist pulling and tension forces

35
Q

What is osteoarthiritis?

A
  • Age related degeneration
  • Degeneration of articular cartilage so narrowing of joint space, bone rubs against bone
  • Growth of bony spurs, osteophytes, that cause inflammation and pain
36
Q

What is rheumatoid arthiritis?

A
  • Autoimmune disease
  • Inflammation of synovial membrane, thickening joint capsule
  • Damage to underlying bone and articular cartilage so both degenerate
37
Q

What does a synovial joint look like with rheumatoid arthiritis?

A