Connective Tissues

Question 1

Connective tissue components

Answer 1

Cells 
Extracellular matrix 
- ground substance (hyaluronate proteoglycan aggregates) 
Fibres 
- collagen (e.g. dermis) 
- reticular (e.g. In lymph nodes) 
- elastic (e.g. in the lung)

Question 2

Mesenchymal tissue

Answer 2

• mesenchymal tissue in the foetus gives rise to all the connective tissue among other things
• some mesenchymal cells (spindle shaped) persist in adults and can give rise to new connective tissue cells when healing is required

Question 3

Mucous connective tissue

Answer 3

Wharton’s jelly from the umbilical cord

- specialised almost gelatin-like ground substance

Question 4

Collagen Fibril

Answer 4

Periodic banding which repeats every 68nm 
1.5nm wide 
Every third amino acid is a glycine 
Triple helix of alpha chains 
Tough, flexible molecule

Question 5

Fibroblasts

Answer 5

• secret procollagen which assemble to form the collagen fibrils
• lots of euchromatin
• cells primarily responsible in the formation of scar tissue

Question 6

Lymph node

Answer 6

Collagen bundles
- type I
Reticular fibres
- type III

Question 7

Elastic fibres

look wavy

Answer 7

Elastin is the primary components - surrounded by microfibres called fibrillin
Important in the dermis, artery walls and the sites bearing elastic cartilage e.f. epiglottis

Question 8

Types of connective tissue

Answer 8

Loose irregular 
- wispy collagen and many fibroblasts 
Dense irregular 
- thicker and more abundant collagen and fewer fibroblasts
- layering in every direction to withstand forces from every direction 
Loose regular 
- e.g. dermis  
Dense regular 
- in line with tensile force 
- e.g. tendons

Question 9

Macrophage

Answer 9

• derived from blood monocytes which move into loose connective tissue especially when there is local inflammation
• phagocytic - can degrade foreign organisms and cell debris
• are ‘professional antigen presenting cells’ to T lymphocytes of the immune system

Question 10

Mast cell

Answer 10

cytoplasm contains abundant granules containing
- heparin (anticoagulant)
- histamine (increase blood vessel wall permeability - local odema)
- substances that attract eosinophils and neutrophils
secretions can result in immediate hypersensitivity reactions, allergy and anaphylaxis
not present in the CNS - do not want inflammation in the brain

Question 11

Adipose tissue

Answer 11

White - multiple droplets fuse to form a single large droplet which displaces the cell cytoplasm and nucleus to the side of the cell
Brown - the multiple lipid droplets remain separate
- brown because of rich vascular supply and abundant mitochondria
- uncoupled to make heat instead of ATP
- important for non-shivering thermogenesis in babies

Question 12

Functions of connective tissue

Answer 12

• provides substance and form to body and organs
• medium for diffusion of nutrients and wastes
• attached muscle to bone (tendons) or bone to bone (ligaments)
• cushion between tissue and organs
• defends against infection
• aids in injury repair