Lecture 14 - Cartilage and Bones

Question 1

What are the three types of cartilage and what fibres do they contain?

Answer 1

Hyaline - Collagen II Elastic - Elastin Fibrocartilage (fibrous) - Collagen I mostly and II minimally

Question 2

What do all cartilage matrices contain?

Answer 2

Proteoglycan in matrix Hyaluronic acid in matrix Chondrocyte cells

Question 3

What are isogenous groups of Chondrocytes?

Answer 3

“Same origin” Small clusters of chondrocytes as a result of very rare mitotic division of them

Question 4

What is a lacunae?

Answer 4

“Lake” or empty space between chondrocytes which is full of matrix

Question 5

What is the epiphyseal plate? How does it form?

Answer 5

During long bone development, hyaline cartilage remains at articulating surfaces of bones. These areas are designed to continuously grow until around 24 years old.

Question 6

What do chondrocytes do?

Answer 6

Lay down extracellular matrix of cartilage

Question 7

What is the purpose of the extracellular matrix?

Answer 7

Allows diffusion of materials in/out of the cartilage

Question 8

What does Hyaluronic Acid do to matrix? Describe matrix.

Answer 8

Matrix is solid and firm, but pliable Hyaluronic Acid assists resilience of matrix from repeated application of pressure

Question 9

What is the purpose of the proteoglycan structure?

Answer 9

Part of ground substance, makes stiff like gel substance in cartilage.

Question 10

Compare no. of hyaluronate-proteoglycan aggregates per collagen fibre in cartilage vs CT.

Answer 10

100 in cartilage vs 10 in CT

Question 11

Where is Hyaline Cartilage found in the body?

Answer 11

Nasal Larynx, Trachea, Bronchi etc. Costal cartilage (ribcage) Intervertebral Disc Articular cartilage of knees (meniscus) Articular cartilage of shoulder, elbows, wrists etc.

Question 12

Describe appositional growth.

Answer 12

Growth of chondrocytes occurs from outside edge of cartilage, the perichondrium. Perichondrium contains elongated fibroblast-like cells that develop into chondroblasts then chondrocytes. Increases width of cartilage.

Question 13

Describe interstitial growth.

Answer 13

Growth of chondrocytes occurs within the cartilage lacunae. Increases length and density of cartilage.

Question 14

How does the fact that the matrix is highly hydrated benefit the Hyaline cartilage?

Answer 14

Water is non-compressible so permits resilience to increase load of pressure.

Question 15

Describe Trachea cartilage.

Answer 15

C-shaped rings of Hyaline Cartilage that keep trachea open.

Question 16

Where is elastin found in the body? (Hint: only 3 places)

Answer 16

Pinna of the ear (and external part of Acoustic Meatus) Eustachian Tube (tube of inner ear to oral cavity) Epiglottis

Question 17

In the Pinna what type of cartilage growth occurs?

Answer 17

Interstitial growth.

Question 18

What distinction does fibrocartilage have to other cartilage?

Answer 18

Fibrocartilage has fibroblasts

Question 19

Describe structure of Fibrocartilage.

Answer 19

Combo of dense regular CT and hyaline cartilage Cells distributed in rows No surrounding perichondrium

Question 20

Where is fibrocartilage found in the body? (Hint: There are 3 places).

Answer 20

Cartilage in intervertebral disc (Sternoclavicular and Temporomandibular)

Meniscus (knee padding)

Pubic Symphasis (joins two pelvic parts)

Question 21

Function of Fibrocartilage?

Answer 21

Resilience to act as shock absorber and resist shearing forces

Question 22

What process allows long bones to develop? What do they form from?

Answer 22

Endochondral Ossification

From Hyaline Cartilage Model, Hyaline is precursor for most bones

Question 23

What are growth plates(epiphyseal plates) on bones? What are they made of?

Answer 23

Parts of bones on ends which are made of hyaline cartilage and continuously grow until 24.

Question 24

Describe the process of endochondral ossification.

Answer 24

Question 25

State as much as you know about Osteoprogenitors.

Answer 25

Undifferentiated cells

Exist in inner layer (endosteum) and outer layer (periosteum)

Immature versions of Osteoblasts (need GF)

Question 26

State as much as you know about Osteoblasts.

Answer 26

Sit on inner layer (endosteum) of spicules

Intermediate cells and cannot divide

Lay down and form new bone

Produce collagen and proteins (Osteocalcin and Osteopontin that make Osteoid)

Mature into Osteocytes

Question 27

State as much as you know about Osteocytes.

Answer 27

Fully differentiated in bone cell

Trapped in Osteon and occupy Lucanae

No longer lay down matrix - Now maintain tissue

Branch out via extensions that signal w/ other cells to allow movement of substances between them

Question 28

State as much as you know about Osteoclasts

Answer 28

HUGE cells (50 nuclei)

Formed from WBCs

On surface of bones, responsible for bone resorption and breaking

Work hand in hand with Osteoblasts to make bone strength

When resorpting, lies in resultant depression in bone which proves its function

Question 29

Describe this diagram

Question 30

What is Osteoarthritis?

Answer 30

Age related degeneration

Failure of articular cartilage

Leads to bone friction and permits smooth articulation

Question 31

What is Rheumatoid Arthritis

Answer 31

Autoimmune disease

Inflammation of Synovial Membrane + Thickening of joint capsule

Leads to damage to underlying bone and cartilage

Both disintegrate