Connective Tissue

Connective tissue is one of the four basic types of animal tissue (including epithelial, muscle and nervous tissue). The main function is to connect tissues and organs and is seen in most parts of the human body. It is responsible for support, protection, insulating, storage of reserve fuel, and transporting substances. Connective tissue is made up of cells, fibres and ground substances, with the latter two making up the extracellular matrix.  

 

There are broad types of connective tissue:

Connective Tissue Proper:

  • Loose Connective Tissue is the most common type and attaches epithelial tissue to other underlying tissues holding organs, nerves blood and lymph vessels in place. It provides support, flexibility and strength. There are three main types of loose connective tissues (collagenous fibres, elastic fibres and reticular fibres).

  • Dense Connective Tissue links bones together at joints and attaches muscles to bones. It can be categorised into dense regular (tendons and ligaments), dense irregular (dermis layer) and elastic connective tissues (arteries, vocal and bronchial tubes in the lungs). 

  • Specialised Connective Tissue encompasses several different tissues with specialised cells. Examples can include bone, blood, and cartilage.

Ehlers-Danlos Syndrome (EDS) is a connective tissue disorder that occurs due to a variety of defects that can impact collagen production, processing or structure. While some cases of EDS are from a spontaneous mutation the majority of EDS is inherited. The genes specific to EDS provide instructions for making the proteins that work with collagen. 

EDS Genes:

Collagen primary structure and processing: ADAMTS2, COL1A1, COL1A2, COL3A1, COL5A1, COL5A2

Collagen folding and cross-linking: PLOD1, FKBP14

Structure and function of myomatrix: TNXB, COL12A1

Glycosaminoglycan Biosynthesis: B4GALT7, B3GALT6, CHST14, DSE

Complement Pathway: C1R, C1S

Intracellular Processes: SLC39A13, ZNF469, PRDM5

Collagen is a tough protein which is the main structural protein in the extracellular matrix within connective tissue. It also makes up 25-35% of all the bodies protein making it the most abundant protein in the human body. Collagen provides the structural strength to the majority of human tissue. It can be found in most areas of the body where connective tissue is found including the heart, blood vessels, skin, eyes, bone, and organs, etc. When there is a defect in collagen (like with EDS) this can result in systemic weakening and instability in multiple areas of the body. It is an essential building block in both the strength and flexibility of connective tissue. There are 28 Collagen types [3].

Taking supplements for collagen has not been found to have any positive impact on EDS as any extra collagen produced will still have the defect. 

References:

[1] https://courses.lumenlearning.com/nemcc-ap/chapter/connective-tissue-supports-and-protects/

[2] https://opentextbc.ca/anatomyandphysiology/chapter/4-3-connective-tissue-supports-and-protects/

[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3003457/

connective tissue.jpeg