Histology of Soft Connective Tissue

Question 1

Describe what is meant by connective tissue

Answer 1

Consists of cells embedded in an extracellular matrix. The matrix varies in composition depending on function

Question 2

List the structures in and around connective tissue from outside to inside

Answer 2

Above connective tissue is epithelium and basal lamina. In the connective tissue is collagen fiber, macrophages, capillaries, mast cells, fibroblasts, glycoproteins

Question 3

What makes up the majority of the extracellular matrix?

Answer 3

Proteoglycans

Question 4

What are the functions of soft connective tissue? (5)

Answer 4

1. Space filler and mechanical support
2. Attachment and protection
3. Highway for nutrients
4. Storage - fat and calcium
5. Site of immunological defence

Question 5

What are the 5 types of soft connective tissue and describe each?

Answer 5

1. Mesenchyme = embryonic
2. Loose (areolar) = mesentery, under dermis
3. Dense = tendon, dermis, capsules
4. Reticular = bone marrow, lymph nodes
5. Adipose = fat cells

Question 6

What are the 3 major proteins in the extracellular matrix?

Answer 6

Collagen for strength, elastin for elasticity and adhesive proteins for attachment of proteins to cells

Question 7

What does collagen form in the extracellular matrix?

Answer 7

It forms fibrils

Question 8

What are type 1, 2 and 3 collagen for?

Answer 8

1 is for skin, bone, tendons, dentine. 2 is for cartilage and 3 is for blood vessels and skin

Question 9

What protein cross links cells of the connective tissue to extracellular matrix?

Answer 9

Integrins

Question 10

What are major extracellular matrix that integrins bind cells to called?

Answer 10

Fibronectin & Collagen, Tenascin and Laminin

Question 11

What are GAG’s synthesised as?

Answer 11

Proteoglycans

Question 12

What does the basal lamina (basement membrane) separate?

Answer 12

The connective tissue from the epithelial cell layer. It is a physical barrier maintaining cell integrity.

Question 13

What is the structure of all GAG’s?

Answer 13

70-200 sugar polymers formed of a repeating disaccharide subunit.

Question 14

Give 4 properties of GAG’s

Answer 14

1. Sugar chains are too stiff to fold into compact structures
2. Strongly hydrophilic
3. Tend to adopt highly extended shaped occupying a large volume
4. Water sucked into the matrix by osmotically active ‘ion cloud’ due to all those negative charges

Question 15

What is the job of GAG’s?

Answer 15

Water creates swelling pressure (turgor) and this enables extracellular matrix to withstand compressive forces.

Question 16

What are the two types of connective tissue called?

Answer 16

1. Indigenous (permanent residents)

2. Immigrant (immune system cells which come in and out depending on the state of the body)

Question 17

What are 3 examples of indigenous cells?

Answer 17

1 = Fibroblasts to produce extracellular matrix
2 = Adipocytes which store fat and leptin secretion
3 = Mast cells for histamine secretion

Question 18

What stem cells give rise to indigenous cells?

Answer 18

Mesenchymal cells