Lecture 6 Flashcards
Connective tissue Function
- Connecting framework of the body
a. Continuous with other basic tissue types
b. Stroma – connective framework of body organs and glands
c. Medium for diffusion of metabolites - Supportive framework of the body
a. Cartilage, bones, ligaments and tendons - Protection and defense
a. Immune and inflammatory responses
b. Tissue repair after injury - Fat storage
Connective tissue components
• Extracellular matrix (ECM) and cells
• ECM contains:
– Ground substance
– Fibers
– It generally contains blood
and lymphatic vessels
What is depicted by the Green and blue arrows
- Ground substance (Blue)
- Fibers (collagen and elastic) (Green)
Ground Substance
- Glycosaminoglycans (GAGs)
- Proteoglycans:
- Glycoproteins
What are the arrows pointing to
- Collagens: tensile strength
- Elastic fibers:ability to return to original shape
What type of fiber is shown in the image
Collagen I fibers
Light microscopy of type I collagen fibers stained pink. F: fibroblasts.
What type of fiber is shown in the image
Collagen I fibers
Electron microscopy of type I collagen fibers:
Fibrils show periodicity at 68 nm (arrow)
What type of fiber is shown in the image
Organization of type I collagen fibers
Collagen I fibers
- Flexible with high tensile strength
- The main structural collagen and is found in fibrous supporting tissue, skin (dermis), tendons, ligaments and bone.
- When examined with the TEM, collagen fibers appear as bundles of fine, thread- like subunits, the collagen fibrils
Reticular Fibers (type III collagen)
- Formstroma(delicate supporting network) around functional cells (parenchyma) of many organs such as endocrine glands, lymph nodes, bone marrow and liver.
- StainpoorlywithH&Ebut stain with silver salts
What type of fiber is shown in the image
Reticular fibers (arrows, silver stain)
What is depicted in the image and what is the arow pointing to
Liver cirrhosis
arrow pointing to collagen build up
Example of fibrosis
Fibrosis
Fibrosis is defined by the overgrowth, hardening, and/or scarring of various tissues and is attributed to excess deposition of extracellular matrix components including collagen.
What does fibrosis result from
• Results from chronic inflammatory reactions induced by a variety of stimuli including persistent infections, autoimmune reactions, allergic responses, chemical insults, radiation, and tissue injury.
What is depicted in each image shown
Elastin fibers (arrows) are seen in the mesentery (a), dermis (b) and in the wall of aorta (c)
Elastic Fibers
- They have rubber-like properties that allow tissues to stretch or bend and recoil
- Present in large amounts in tissues such as lung, skin, urinary bladder and the wall of blood vessels
- They are composite of fibrillin which forms a network of microfibrils, embedded in a larger mass of cross-linked elastin
What is shown in the image
Electron micrographs of Elastin fibers (E). Arrows show the fibrillin microfillaments
What is shown in the image
Fibroblasts (arrows)
What is shown in the image
Myofibroblasts (arrows)
Fibroblasts
- Synthesize collagen, elastic and reticular fibers and the complex carbohydrates of the ground substance in the ECM.
- During wound healing fibroblasts differentiate into myofibroblasts to repair the damaged organ
Permanent supporting (resident cells). They develop and remain in connective tissues
– Fibroblasts
– Adipocytes
Transient defense cells develop elsewhere, migrate into connective tissues for surveillance and in response to specific stimuli
– Macrophages
– Mast cells
– Plasma cells
– Leukocytes