Connective tissues

Question 1

Function of connective tissues

Answer 1

To provide general structure, mechanical strength, space filling and physical and metabolic support for more specialised tissues.

Question 2

Components of connective tissues

Answer 2

Connective tissues are made up of cells and the extracellular matrix, which is composed of fibres and ground substance.

Question 3

Cells of connective tissues

Answer 3

• fibroblasts; deposit all components of the ECM
• plasma cells; produce antibodies
• adipocytes; store lipids
• macrophages; perform phagocytosis
• fibrocytes
• eosinophils
• neutrophils
• lymphocytes
• mast cells; store bioactive substances (eg.histamine, heparin) in granules

Question 4

Fibres of connective tissues

Answer 4

3 types of fibres are produced by fibroblasts:

• collagen fibres
• reticular fibres
• elastic fibres

Question 5

Collagen fibres

Answer 5

The most abundant fibre in the body, collagen is thick and tough with a high tensile strength. Collagen fibres run in bundles and do not branch. There are many different types of collagen fibre.

Question 6

Location of collagen types

Answer 6

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Type I) Bones, Skin, Tendons
Type II) Cartilage
Type III) Reticulin and blood vessels
Type IV) Basement membrane

Question 7

Reticular fibres

Answer 7

Thin and delicate fibres composed of reticulin (type III collagen), which form the scaffolding framework (stroma) for organs.

Question 8

Elastic fibres

Answer 8

Thin and branching fibres composed of elastin deposited within a fibrulin scaffold. Allow stretching, so are found in tissues such as the lung, bladder, heart and blood vessels.

Question 9

Ground substance

Answer 9

A transparent, semi-solid, gel-like substance comprised of a mixture of glycoproteins and carbohydrates called glycosaminoglycans (GAGs). These are hydrophilic and trap water, contributing to the function of providing volume, compression resistance and tissue turgor. It also facilitates metabolic exchange.

Question 10

Basic types of connective tissue

Answer 10

• loose connective tissue
• dense connective tissue
• adipose tissue

Question 11

Loose connective tissue

Answer 11

• lots of ground substance, some fibres
• binds structures together, forms passage for blood vessels, nerves and lymphatics
• found in basement membranes and surrounding blood vessels

Question 12

Dense connective tissue

Answer 12

• many closely packed fibres, less ground substance
• provides high tensile strength/elasticity
• found in tendons, ligaments and skin

Question 13

Regular connective tissue

Answer 13

Fibres run in one direction; helps with anchorage and connecting structures.

Question 14

Irregular connective tissue

Answer 14

Fibres run in different directions; can withstand various forces.

Question 15

White adipose tissue

Answer 15

• stores lipids for energy release, insulation, shape filling and organ protection
• unilocular cells; contain one fat droplet
• nucleus is pushed to the edge
• larger cells
• found throughout the body in adults

Question 16

Brown adipose tissue

Answer 16

• responsible for thermogenesis
• multilocular cells; contain many fat droplets
• nucleus is central, many mitochondria
• smaller cells
• found in the embryo/fetus and adrenal region of adults