1-50 Connective tissues Flashcards
1
Q
Connective tissues (histology)
A
- supportive framework for all other tissue types in the body
- found in every organ system, keeps epithelium “in line”
- derived from the mesodermal layer during development
- 4 types:
- loose
- dense
- reticular
- adipose tissue
- specialized: cartilage, bone, blood
- FXN: structural support, medium for exchange, fat storage, defense protection, healing and remodeling
- Cell types: fibroblasts, macrophages, adipocytes, pericytes, mast cells, WBCs
Defining features:
- cells separated from one another and surrounded by an ECM that is produced by the cells
- serving fxnl roles of support, medium, fat storage, defsense, healing, remodeling
2
Q
A
Fibroblasts/myofibroblasts
structural support
healing/remodeling
make collagen
3
Q
A
macrophages
structural support
healing/remodeling
4
Q
A
adipocytes
fat storage
5
Q
A
pericytes
structural support
6
Q
A
mast cells
defense, relases cytokines
healing/remodeling
7
Q
connective tissue skin cross section
A
8
Q
dense irregular connective tissue
A
- densely packed fibers with waven collagen fibers in a amtrix with some elastic
- ex. reticular dermis
- impact resistant against multidirectional forces
9
Q
dense regular connective tissue
A
- densely packed fivers with parallel collagen fibers
- ex tendon
- resistant to tension forces
10
Q
loose connective tissue
A
- many different cell types with fewer fibers
- high fat content (ex: superficial fascia under the skin)
- “packing material” throught the body
- High amount of ground substance (looks like empty space under microscope)
- ex: colonic submucosa
11
Q
H&E stain
A
pink: acidic
purple: basic
12
Q
Extracellular matrix
A
- The extracellular matrix provides both structural and biochemical/nutritional support for the other tissues of the body
- Made of fibers (collagen and elastin) and ground substance (glycosaminoglycans)
- FIBERS: Collagen and elastin form the structural framework of the ECM and provide both resistability (collagen) and elasticity (elastin)
Lots of types of collagen (I-IX) but about 90% is Type I and forms the skin, bones, cartilage, ligaments, tendons, etc
- Ground Substance: Made up of glycosaminoglycans like hyaluronan and other glycoproteins that helps with structure. Also hydrates the tissue and is involved in cell migration and cell sensing/reaction to the microenvironment
13
Q
Elastic fibers
A
- made of elastin and microfibrils
- provide elasticity to tissues
- difficult to see with H&E
- random coiling of elastin molecules provides the elasticity, they can b stretched and will return to the original size and shape
- elastin is an amorphous protein secreted from fibroblasts and is crosslinked extracellularly and assembled as a scaffold of microfibrils to form elastic fibers
- fibrillin is part of microfibrils and is required for assemly of elastin into elastic fibers
- without fibrillin, elastin assembles into sheets rather than fibers
- ex: aorta
14
Q
Reticular Connective Tissue
A
- supportive tissues found as branched, interconnecting meshwork in the loose connective tissue stroma of lymphatic tissues
- except thymus
- reticular fibers: fine collagen type 3, stain positive with silver
15
Q
Collagen
A
- most common fibrous protein in the ECM, resists forces, most abundant protein in humans
- glycine and proline with sugar groups
- acidophilic: stains pink in H&E stains
- Vitamin C is required for proper formation of collagen fibers, cross linked, tensile strength
- collagen released from fibroblasts as procollagen and final processing occurs outside the cell
