Connective Tissue

Question 1

What is the classification of connective tissue?

Answer 1

Question 2

What is Mesenchyme? (3)

Answer 2

• Primitive connective tissue
• Found in the embryo
• Formed through proliferation and migration of the
  mesoderm

Question 3

What does mesenchyme contain? (4)

Answer 3

• Contains spindle-shaped cells with processes
• Gap junctions connect processes to adjacent cell
• Ground substance is viscous
• Sparse and fine collagen and reticular fibers

Question 4

What does mesenchyme gives rise to? (4)

Answer 4

o Connective tissue
o Muscle
o Vascular and urogenital systems
o Serous membranes

Question 5

What does mucous connective tissue contain? (4)

Answer 5

• Present in the umbilical cord
• Gelatin-like extracellular matrix (Wharton’s Jelly)
• Contains spindle-shaped cells
• Thin, wispy collagen fibers

Question 6

Components of connective tissue: (3)

Answer 6

1. Cells
2. Fibers
3. Ground substance

Question 7

What is Loose/areolar connective tissue? (4)

Answer 7

• Cellular connective tissue with thin and sparse collagen fibers
• Abundant and viscous ground substance and occupies more volume than fibers
• Responsible for diffusion to and from small vessels
• Initial site of immune reaction

Question 8

What is the location of Loose/areolar connective tissue?

Answer 8

Lamina propria of mucosa (beneath the epithelium)

Question 9

What is Dense irregular connective tissue? (4)

Answer 9

• Contains mostly connective tissue fibers
• Cells are sparse, mainly fibroblasts
• Little ground substance present
• Resistant to stretching, distension and tearing

Question 10

What is the location of Dense irregular connective tissue? (2)

Answer 10

o Submucosa of hollow organs
o Reticular/deep dermis layer of the skin

Question 11

What is Dense regular connective tissue? (3)

Answer 11

• Parallel, densely packed collagen fibers
• Little ground substance present
• Cells are packed and aligned between fiber bundles

Question 12

What is the location of Dense regular connective tissue? (3)

Answer 12

o Tendons
- Fibroblasts are called tendinocytes
- These cells are surrounded by a specialized ECM separating it from loadbearing collagen
o Ligaments
- Some ligaments of the spinal column have abundant elastic fibers
- Called elastic ligaments
o Aponeuroses
- Fibers are parallel in each sheet
- The sheets of fibers are layered perpendicularly

Question 13

What are collagen fibres? (5)

Answer 13

• Most abundant fiber types
• Flexible with high tensile strength
• Stains with eosin
• Each collagen molecule is a triple helix of a chains and is non-branching
• Subunits are collagen fibrils forming a banding pattern

Question 14

What are collagen fibres synthesized by? (5)

Answer 14

Synthesized by:
o fibroblasts
o chondrocytes
o osteoblasts
o pericytes in blood vessels
o epithelial cells (for basement membrane)

Question 15

What are elastic fibres? (5)

Answer 15

• Allow tissues to respond to stretch and distension
• Thinner than collagen fibers
• Arranged in branching pattern to form a 3D network
• Interwoven with collagen fibers to limit distensibility and prevent tearing
• Unusual polypeptide backbone with random coiling

Question 16

What are elastic fibres synthesized by?

Answer 16

• Synthesized by fibroblasts and vascular smooth muscles

Question 17

What are reticular fibres? (3)

Answer 17

• Provide framework for cellular constituents of tissues and organs
• Composed of type III collagen with a banding pattern
• Branched, but do not bundle to form thick fibers

Question 18

Reticular fibres have _______(stain silver) staining.

Answer 18

• Argyrophilic

Question 19

Where are reticular fibres located in loose connective tissue?

Answer 19

o Boundary of connective tissue and epithelium
o Surrounding adipocytes, small blood vessels, nerves and muscle cells

Question 20

Reticular fibres are prominent in _____ healing and ____ formation.

Answer 20

wound
scar

Question 21

What are reticular fibres synthesized by? (4)

Answer 21

o Reticular cells in haemopoietic and lymphatic tissue
o Fibroblasts
o Schwann cells of peripheral nerve endoneuria
o Smooth muscle cells in tunica media of blood vessels and muscularis of alimentary canal

Question 22

What is the function of the Extracellular Matrix? (4)

Answer 22

• Provides mechanical and structural support
• Influences extracellular communication
• Functions as a biochemical barrier
• Regulates metabolic functions of surrounding cells

Question 23

What is the ground substance? (2)

Answer 23

• Viscous, clear, colourless, transparent, amorphous, slippery with high water content
• Supports, surrounds and binds all connective tissue cells and fibers

Question 24

What is the ground substance composed of? (3)

Answer 24

• Composed of specialized proteins and carbohydrates:
  o Proteoglycans
  o Multiadhesive glycoproteins
  o Glycosaminoglycans (GAGs)

Question 25

What is the difference between Resident cells and Wandering/transient cells?

Answer 25

Question 26

What are fibroblasts? (2)

Answer 26

* Principal connective tissue cell * Synthesize all 3 types of fibres and complex carbohydrates of ground substance

Question 27

What is the morphology of fibroblasts? (3)

Answer 27

o In H&E staining, only the nucleus is visible as an elongated disc o Processes extended out of the cell in all directions o Prominent rough endoplasmic reticulum and Golgi apparatus

Question 28

What are macrophages? (4)

Answer 28

* Phagocytotic cells derived from monocytes * Kidney-shaped nucleus present * Cytoplasm contains many lysosomes * Difficult to identify

Question 29

What are adipocytes? (3)

Answer 29

* Stores neutral fat * Produces a variety of hormones, inflammatory mediators and growth factors * Flat, squashed nucleus

Question 30

What are mast cells? (3)

Answer 30

* Develop in bone marrow and differentiate in connective tissue * Large ovoid cell with spherical nucleus * Cytoplasm filled with large, intensely basophilic granules

Question 31

What do granules in mast cells contain? (2)

Answer 31

* Granules contain: o Histamine (causes allergic reactions) o Heparin (anticoagulant)