collagen

Examples of collagen in the following topics:

• Structural Elements of Connective Tissue

  • The fibroblast is the most common cell which creates collagen.
  • The tropocollagen or collagen molecule is a subunit of larger collagen aggregates such as fibrils.
  • In bone, entire collagen triple helices lie in a parallel, staggered array.
  • Model of the collagen triple helix.
  • The tropocollagen or collagen molecule is a subunit of larger collagen aggregates such as fibrils.

• Characteristics of Connective Tissue

  • Collagen fibers are fibrous proteins and are secreted into the extracellular space and they provide high tensile strength to the matrix.
  • Reticular fibers are short, fine collagenous fibers that can branch extensively to form a delicate network.
  • Collagen fibers are the strongest and most abundant of all the connective tissue fibers.

• Basement Membranes and Diseases

  • The lamina reticularis is attached to the basal lamina with anchoring fibrils (type VII collagen fibers ) and microfibrils (fibrillin).
  • In addition to collagen, this supportive matrix contains intrinsic macromolecular components.
  • Genetic defects in the collagen fibers of the basement membrane cause Alport syndrome or hereditary nephritis, a genetic disorder characterized by glomerulonephritis, endstage kidney disease, and hearing loss.
  • Goodpasture disease is the result of an autoimmune response directed at Collagen type IV alpha-3-binding protein, resulting in damage to the lungs and kidneys, bleeding and kidney failure.
  • Collagen is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of vertebrates.

• Lines of Cleavage and Surgery

  • Cleavage lines are topological lines drawn on a map of the human body and correspond to the orientation of collagen fibers in the dermis.
  • They correspond to the natural orientation of collagen fibers in the dermis.
  • Sometimes the exact direction of the collagen fibers is unknown because in some regions of the body there are differences between different individuals.

• Deep Wound Healing

  • The provisional ECM laid down during the proliferative phase is rich in fibronectin and collagen III that combine to allow quicker cell movement through the wound, which is very important during wound healing.
  • However, the ECM of mature skin is rich in collagen I.
  • In large, deep wounds the remodelling of a fibronectin and collagen III-rich ECM to a collagen-I rich ECM may not occur, leading to a weakening of the tissue.

• Structure, Type, and Location of Cartilage

  • Chondrocytes are first chondroblast cells that produce the collagen extracellular matrix (ECM) and then get caught in the matrix.
  • This type of cartilage is predominately collagen (yet with few collagen fibers), and its name refers to its glassy appearance.
  • Fibrous cartilage has lots of collagen fibers (Type I and Type II), and it tends to grade into dense tendon and ligament tissue.
  • It is the only type of cartilage that contains type I collagen in addition to the normal type II.
  • Elastic or yellow cartilage contains elastic fiber networks and collagen fibers.

• Elastic Arteries

  • An elastic artery or conducting artery is an artery with a large number of collagen and elastin filaments in the tunica media.
  • Elastic arteries contain larger numbers of collagen and elastin filaments in their tunica media compared to muscular arteries giving them ability to stretch in response to each pulse.

• Microscopic Anatomy of Bone

  • Bone matrix is laid down by osteoblasts as collagen, also known as osteoid.
  • Woven bone is characterized by the irregular organization of collagen fibers and is mechanically weak, but forms quickly.
  • The regular parallel alignment of collagen into sheets, or, lamellae, causes lamellar bone to be mechanically strong.
  • Woven bone is characterized by the irregular organization of collagen fibers and is mechanically weak.

• Effects of Aging on the Integumentary System

  • Such an aging process may include qualitative and quantitative changes such as diminished or defective synthesis of collagen and elastin in the dermis.
  • Cortisol (associated with stress) causes degradation of collagen, accelerating skin aging.
  • Wrinkles form due to intrinsic (loss of collagen) and extrinsic (photodamage) aging.

• Platelet Plug Formation

  • During an injury, subendothelial collagen from the extracellular matrix beneath the endothelial cells is exposed on the epithelium as the normal epithelial cells are damaged and removed, which releases von Willebrand Factor (VWF).
  • VWF causes the platelets to change form with adhesive filaments (extensions) that adhere to the subendothelial collagen on the endothelial wall.
  • After platelet adherence occurs, the subendothelial collagen binds to receptors on the platelet, which activates it.