L5-L6 Connective Tissue I Flashcards
What the basic functions of connective tissue? (5)
- Structural framework of the body
- Conducts and translates muscle contractions into movement
- Forms stroma of glands and organs
- Medium for metabolic exchange
- Site of fat and mineral storage
General characteristics of connective tissue
- Low cell density, extensive extracellular matrix
- Tend to be highly vascular (except cartilage)
- Most retain stem/ mitotic cells (tissue growth and regeneration)
What is connective tissue composed of? Which of the two is the MAJOR constituent?
Cells, and ECM* which is the major constituent
What is the extracellular matrix (ECM) made of? (2)
- Ground substance
2. Fibers
What are the ECM’s ground substance and fibers characteristics? (3)
- Determines physical properties
- Varies greatly with tissue type
- Synthesized and secreted by cells
What is ground substance? (3)
- Colorless, transparent, gel-like
- Highly hydrated
- Mixture of macromolecules
What are the three substances in the mixture of macromolecules in ground substance?
- Proteoglycans (PGs)
- Glycosaminoglycans (GAGs)
- Multiadhesive glycoproteins
What are the GAGs? (3)
Glycosaminoglycans:
- Repeating disaccharide units
- Negatively charged, attracts Na+
- Hydrating element of ground substance
What are the PGs?
Proteoglycans:
- GAGs (glycosaminoglycans) covalently bonded to core protein
What are the functions of PGs? (2)
- Cushion against compression (keeps puffy(
- Aids in material exchange
Features of ground substance? (2)
- Extremely large aggregates of PGs
2. Enhance role of GAGs in the tissue- “biological sponge”occupies large volume; resists fluid movement
What is specific to the adhesive glycoproteins of ground substance? Also what is bound to that?
Bind cells to ECM, which has cell (cytoskeleton) attached to it
The ECM is made of collagen & elastic too, what are some characteristics? (3)
- Determines physical properties
- Varies greatly with tissue type
- Synthesized and secreted by cells
What is exclusive about collagen?
Most common protein in the body
What are features of collagen fibers?
- Fibrous proteins present in large quan in CT
- Imparts tensile strength (flexible but not elastic)
- Often self-assemble into higher-order structures: fibrils, fibers, bundles
What is the organization of collagen?
Muscle -> Tendon -> Collagen fiber -> Fibril (one dark + one light = periodicity)
What are the collagen fibrils vs fibers?
Collagen FIBRILS- each one strand (earthworm like) whereas FIBERS is when the fibrils bundles
What is the *most common type of collage and what are some characteristics (3)?
Type I collagen:
- HIGHEST tensile strength
- Gross: white
- LM: pink (acidophilic..which means stains with Eosin) fibers and bundles with H & E
Where is Type I collagen found?
Bone, teeth, ligaments/ joint capsules, tendons, dermis of skin, fibrocartilage (all places where we find periodicity = collagen*)
What are Type II collagen?
Slender fibrils found in cartilage (bendy)
What are Type III collagen?
Reticular (hatch) fibers
What is the function of Type III Collagen?
Functions to filter fluid: appears delicate, branching, dark-staining with silver, ex) found in lymph nodes
At EM we can see the basement membrane, which is made out of? What do they each secrete?
Basal lamina (secreted by ET) + Reticular lamina (secreted by CT)
Collage is secreted by___?
Epithelial tissue