Connective Tissues

Question 1

Function of connective tissue?

Answer 1

-form supporting framework for the body.
-bind/connect together the body cells and tissues.

Question 2

Composition of connective tissue?

Answer 2

Living cells
Extracellular matrix

Question 3

Describe the extracellular matrix

Answer 3

Produced and maintained by the connective tissue cells.
Defines the structural properties of the connective tissue
-composed of fibres and ground substance

Question 4

What is the importance of fibres and ground substance

Answer 4

The relative proportion of fibres to ground substance determine both the structure and function of ECM

Question 5

Connective tissue categories

Answer 5

-Loose connective tissues for spacing and packing (e.g. adipose tissue)
-Dense fibrous connective tissues for protection and attachment (e.g. ligaments and tendons)
-Specialised connective tissues Cartilage, bone, dentine, enamel, blood

Question 6

What are two groups of cells in connective tissue

Answer 6

Structural cells for synthesis and maintenance of the structural components
Defence cells for non-specific defence reactions

Question 7

What are examples of structural cells

Answer 7

Fibroblasts.
Adipocytes (fat cells).
Chondrocytes (cartilage cells).
Bone cells (e.g. osteoblasts, osteocytes)

Question 8

What are the major structural cells

Answer 8

Fibroblasts: make collagen and other ECM components and maintain it
 Adipocytes (fat cells) have protective and
thermoregulatory
functions

Question 9

What do adipocytes appear as

Answer 9

Empty unless lipids are retained and stained

Question 10

What are Mesenchymal stem cells (MSCs)

Answer 10

MSCs are:
 indistinguishable from fibroblasts.
 can differentiate (“mature”) into new connective tissue cells.
 present in small numbers

Question 11

What are the major defence cells

Answer 11

-MACROPHAGES are motile cells that can engulf foreign material e.g. bacteria or carbon
-NEUTROPHILS or LYMPHOCYTES are present during inflammatory reactions

Question 12

Describe the structure of ground substance

Answer 12

Semi-solid gel through which metabolites can diffuse
Made up of proteins and fluid.
 Many ECM proteins are a complex mixture of long chain molecules with side chains

Question 13

What Two major fibre types are found in the ECM

Answer 13

Collagen fibres (common) – high tensile strength.
Reticular fibres. These are delicate fibres made up of collagen.
Elastin fibres (less common) – low tensile strength but elastic

Question 14

Describe the collagen fibres in ECM

Answer 14

Collagen fibres are made up of the protein collagen (body’s “biological rope”).
 Collagen most common protein in ECM and body.
 Various collagen types:- some of which can form fibres.
[Collagen = 25% of total dry mass of body protein]

Question 15

Fibres in the periodontal ligament

Answer 15

Question 16

Describe Elastin fibres in the ECM

Answer 16

Elastin fibres:
 a minor component of most connective tissues
 Found in particular in areas where elasticity is an advantage e.g. large arteries

Question 17

Describe the components of the ground substance

Answer 17

Proteoglycans: protein core to which is attached many carbohydrate side chains.
 hydrophilic = bind water up 10X their own weight to produce a jelly-like consistency.
Glycoproteins: protein core with some sugar side chains.
Long carbohydrate chains: no protein core, they are long chains of glycosaminoglycans [GAGs].
 e.g. hyaluronic acid

Question 18

Name 3 examples of connective tissue

Answer 18

-loose connective tissue
-adipose tissue
-skin

Question 19

Describe loose connective tissue

Answer 19

Formed throughout the body composed of fine fibres of collagen, elastin and reticulin.
 Helps to fill spaces between larger organs.
 Forms loose sheets around blood vessels,
nerves, tendons. Connects muscle layer and skin.
 Soft, pliable tissue.

Question 20

Describe adipose tissue

Answer 20

 Made up of a mass of fat-filled cells
.  Supporting tissue (e.g. beneath the
skin providing smooth body outline).
 Storage of fat.
 Insulation/protection

Question 21

Skin - An example to show how the relative amounts of fibre and other elements can alter the properties of connective tissue to match their function

Answer 21

Question 22

What specific mechanical properties does cartilage have because of specialised ECM components

Answer 22

Hyaline cartilage: (lines articulating surfaces of joints, nasal septum, tracheal rings). Very dense matrix of collagen fibres and “ground substance”.
Fibrocartilage (contains collagen 1):
found in intervertebral discs, pubic symphysis, menisci of joints,
tempromandibular joint). Thick interlaced collagen fibres in matrix and less ground substance.
Elastic cartilage: found in ear and epiglottis. Provides a rigid but elastic framework. Matrix composed of elastin and collagen fibres and some ground substance.

Question 23

Structure of an articulate joint

Answer 23

Question 24

Function of articular cartilage

Answer 24

Articular cartilage functions as a biological “shock absorber” to protect the bones during joint movement and provide smooth, low friction surface for movement. Functions due to ECM structure.

Question 25

Structure of Temporomandibular Joint (TMJ)

Answer 25

Question 26

Cartilage examples

Answer 26

Hyaline cartilage e.g. found on joint surfaces, nasal & costal cartilages. Fibrocartilage Found in areas of high impact e.g. intervertebral discs, TMJ.

Question 27

Structure of bone

Answer 27

One of hardest connective tissues when fully developed. Its a mineralised tissue Dental tissues (enamel, dentine, cementum) hardest connective tissues. Bone is 30% organic material (majority is collagen), 45% inorganic [hydroxyapatite (HA)-a hydrated crystalline material of calcium and phosphate]. Hydroxyapatite provides strength. HA content: Bone approx. 45% cementum 55% dentine (70%), enamel (90%)

Question 28

Describe bone

Answer 28

Bone is a living dynamic tissue. Constructed to ensure maximum strength for minimum weight.  Changes all the time to meet stress loads and to release Ca++ and phosphate if required.

Question 29

Function of bone

Answer 29

Provides support for body.  Protection of internal organs.  Houses and protects the bone marrow  Mineral Store (99% body Ca, 85% P04)  Bones move relative to each other and the environment for bodily movement and locomotion  Two types of bone:  Cortical/Compact:-dense, very strong, forms the outer layer of all bones.  Trabecular/Cancellous: (weak, porous meshwork)