Histology Lecture 11 and 12 - Connective Tissue I and II Flashcards
What are the connective tissue functions?
1) Physically support other tissues
2) bind other tissues together
3) provide a structural framework that opposed gravity
4) helps create body contours
5) house specialized tissues (i.e. hematopoietisis in long bonds)
What characterizes Loose Connective Tissue?
In Loose CT, both collagen and elastic fibers are present and arranged in a loose, random fashion.
Describe Embryonic Connective Tissue.
Embryonic connective tissue is found in the umbilical cord (Wharton’s Jelly) and pulp of the developing tooth. It is composed of some collagen and elastic fibers, but is mostly an abundance of extracellular matrix.
Function: close off the umbilical vasculature once the umbilical cord is severed.
Describe Loose Connective Tissue.
Loose Connective Tissue, or Areolar CT, contains a high ratio of fibroblasts to fibrous components. Type I and elastic fibers predominate.
Describe Dense Regular CT.
Dense Regular CT contains a high ratio of fibrous components to fibroblasts. It is characterized by highly ordered bundles of collagen separated by single rows of fibroblasts. This configuration imparts great tensile strength and Dense Regular CT is found in tendons and ligaments.
Describe Dense Irregular CT.
Dense Irregular CT contains a high ratio of fibrous components to fibroblasts, however, has no specific orientation of collagen bundles and therefore has low tensile strength.
Describe Reticular CT.
Reticular CT is a type of dense irregular connective tissue with a predominance of reticular fibers. It is primarily associated with lymphatic tissue.
Reticular fibers are agyrophilic (stain well with Silver)
Describe Elastic CT.
Elastic CT is a type of dense irregular connective tissue with an abundance of elastic fibers which form discontinuous lamellae. It is associated with the walls of blood vessels.
What are adipocytes?
Adipocytes are fat cells, most approximately 150 micrometers in diameter.
What differentiates brown fat from white fat?
White fat is the more ubiquitous type of fat and is unilocular.
Brown fat cells are multilocular, and are found between the should blades. They are more present in infants and are involved with not shivering thermogeneration. The brown color is due to an abundance of mitochondria.
Where is Type I collagen found and what is its function?
Type I collagen is found in tendons, ligaments, and bone and functions in tensile strength.
Where is Type II collagen found and what is its function?
Type II collagen is found in hyaline and elastic cartilage and functions in tensile strength.
Where is Type III collagen found and what is its function?
Type III collagen is found in the parenchyma of organs and in the walls of blood vessels. It functions in providing the reticular framework.
Where is Type IV collage found and what is its function?
Type IV collagen is found in the basement membrane and functions to provide a meshwork, or scaffolding, to epithelial cells.
Describe Type I Collagen Fiber Synthesis.
1) Collagen Type I is synthesized as a prepropeptide. The pre- sequence is cleaved prior to secretion. Left with procollagen.
2) The propeptide is secreted by the fibroblast into extracellular matrix
3) pepitdases cleave terminal non-helical ends on the pro- sequences from the collagen. Left with tropocollagen.
4) Spontaneous polymerization of tropocollagen into characteristic 64 nm bands
