Cartilage

Question 1

What are the main functions of cartilage?

Answer 1

Semi-rigid support to many specific cells
Shock absorber
Protects ends of bones

Question 2

Ligaments provide:

Answer 2

stability of joints and connect bone to bone

Question 3

Tendons provide:

Answer 3

Strong, flexible connects between muscle and bones

Question 4

Where does the skeletal system originate from ?

Answer 4

undifferentiated mesenchymal cells that can differentiate into various cell types: bone, fibrous tissue

Question 5

Where is differentiation and maturation most advanced?

Answer 5

at the center of mass of growing cartilage; immature at periphery (perichondrium)

Question 6

Completion of growth of cartilage mass consists of…

Answer 6

chondrocytes embedded in a large amount of extracellular matrix

Question 7

What happens at the periphery of the mature cartilage?

Answer 7

There is a zone of condensed CT (perichondrium), containing elongated fusiform cells that resemble fibroblasts. These cells give rise to chondroblasts

Question 8

When is cartilage avascular?

Answer 8

In adult, though young animals have blood vessels in growing cartilage

Question 9

What type of tissue does cartilage support?

Answer 9

Soft tissue

Composed of cells (chondrocytes) that are embedded in an amorphous gel-like substance and connective tissue fibers, making this tissue resilient

Question 10

Why is important for cartilage to support soft tissue?

Answer 10

For longitudinal bone growth – endochondral ossification

Question 11

What are the stages of chondrogensis?

Answer 11

a = embryonic mesenchyme

b= proliferation and early differentiation

c = chondroblasts separate from each other due to production of matrix

d = multiplication of cartilage cells in aggregates

Question 12

Isogenous group

Answer 12

cluster of chondrocytes formed through the division of a progenitor cell; found in hyaline cartilage, elastic cartilage, and fibrocartilage

Question 13

What is endocondral ossification?

Answer 13

cartilage in physes matures, dies, mineralized and forms scaffold to form bone – longitudinal growth of bones

Primary ossification centers form first at epiphyses

Question 14

Growth plate (physis)

Answer 14

1. Zone of reserve/resting cells
2. Zone of proliferation
3. Zone of hypertrophic cells
   B. Primary spongiosa - bone forms on dead mineralized cartilage “scaffold”

Question 15

What are the type of cartilage based on?

Answer 15

the amount of collagen or elastic fibers present in the extracellular matrix as well as the presents of GAGs

Question 16

What are the types of cartilages

Answer 16

1. Hyaline
2. Elastic
3. Fibrocartilage

Question 17

Describe Hyaline cartilage

Answer 17

Most abundant cartilage

Location: growth plates = physes

Articular cartilage covers joint surfaces at costochondral junctions of the ribs, the nasal septum, larynx, tracheal rings and bronchi

Fetal axial and appendicular skeletal

Perichondrium: presented

Question 18

Describe Elastic Cartilage

Answer 18

Perichondrium, chondroblasts and chondrocytes in large lacuna

Elastic fibers stain dark

Flexible due to the presence of numerous bundles of branches in elastic fibers in cartilage matrix

Location: Ear pinna (external auditory), epiglottis, the corniculate and cuneiform processes of the arytenoid cartilage

Question 19

Describe Fibrocartilage

Answer 19

Lacks a perichondrium - therefore does not have the capacity to regenerate

Contains chondrocytes and lacunae and type 1 collagen fibers

Features are intermediate between cartilage and dense fibrous connective tissue

Location: where support and tensile strength are required: Intervertebral discs (annulus fibrosus) menisci, insertions of tendons and ligaments, mandibular symphysis, pubic symphysis

Question 20

What is the matrix of cartilage

Answer 20

composed of collagen, elastic fibers, proteoglycans (GAGs)

Question 21

Outer layer of perichondrium

Answer 21

the outer layer is composed of dense fibrous CT; resembles mature fibroblasts.

Question 22

the inner layer of perichondrium

Answer 22

The inner layers is cellular and it is presented in all hyaline cartilage EXCEPT on articular surfaces → inner layer: is chondrogenic, contains cell with the capacity to become chondroblasts (can regenerate) BUT not present in articular cartilage

Question 23

What is the reason for the cartilage matrix to be so basophillic

Answer 23

due to the high concentrations of GAGs `

Question 24

What are the importance of GAGs

Answer 24

Bound to a protein core form macromolecules called proteoglycans that are responsible for strong and flexible property of cartilage → shock absorption (increase ground substance)
Give rise to different types of cartilage

Question 25

What is territorial

Answer 25

the matrix near the clusters of chondrocytes more basophilic due to the greater amount of GAG than the matrix further away from the chondrocytes (interterritorial)

The tissue surrounding chondrocytes (cells which produce cartilage)

Question 26

What is (interterritorial)

Answer 26

The matrix further away from the chondrocytes

the matrix that occupies the majority of space between chondrocytes

Question 27

Chondroclasts

Answer 27

breakdown/absorption of cartilage

Question 28

Chondrocytes

Answer 28

mature cells embedded in cartilage matrix within lacunae

Question 29

Chondroblasts

Answer 29

Deposit cartilage matrix

Question 30

What is tendon primary composed of?

Answer 30

primarily composed of type 1 collagen (elastic and strong)
Parallel bundles of type 1 collagen fibers in tendon

Question 31

Mature tendon?

Answer 31

Mature tendon cells have a limit ability to regenerate:

Following injury, a tendon lays down type III collagen → stronger than type I but stiffer and less elastic → makes it less flexible and prone to re-injure when the animal begins to stretch the tendon during strenuous work

Question 32

What are the types of joint?

Answer 32

Fibrous joints (Synarthroses)
Cartilaginous (Amphiarthrosis)
Synovial (Diarthrosis/true joints)

Question 33

What is Fibrous joints (Synarthroses)

Answer 33

Bones or cartilage united by fibrous tissue suture (cranial), Syndesmosis (tibia-fibia)
Gomphosis (tooth socket)

Question 34

What is Cartilaginous (Amphiarthrosis)

Answer 34

unites cartilage and bone by hyaline cartilage or fibrocartilage

Question 35

What is Synovial (Diarthrosis/true joints)

Answer 35

units two bone ends and are covered by articular cartilage and surrounded by a thick articular capsule

Question 36

Bone surface is covered by

Answer 36

hyaline cartilage (articular cartilage)

Question 37

What is the articular surface?

Answer 37

should be smooth; formed by type II collagen and proteoglycans; avascular → limited capacity for repair + nourish from synovial fluid

Question 38

What is the articular capsule?

Answer 38

thick sac of connective tissue that covers the entire joint and provide additional joint stability

Question 39

What is the synovial membrane

Answer 39

thin membrane with lots of vili superficial lined by a continuous layer of specialized cells

Question 40

What are the type of cells found in the synovial membrane

Answer 40

Type A and Type B cells

Question 41

What are type A cells of the synovial membrane

Answer 41

Phagocytic function - remove debris

Question 42

What are the type B cells of the synovial membrane

Answer 42

secrete hyaluronic acid & protein complex (mucin) into synovial fluid = lubricant, protectant + nutrition to joints

Question 43

What is synovial fluid?

Answer 43

clear, viscous, colorless or slightly yellow fluid produced by synoviocytes (low cellularity and low protein content); function is to reduce friction; increases in many joint diseases (effusion)

Question 44

What is lacunae

Answer 44

Lacunae are spaces in which bone cells are present. The main purpose of a lacuna in bone or cartilage is to provide a home for the cells it contains while also keeping them alive and functional. In bones, lacunae encase osteocytes; in cartilage, lacunae enclose chondrocytes.