General Anatomy (connective Tissue) Flashcards
What are the characteristics features of CT?
- large amount of extracellular matrix
- cells are widely separated
- connect the cells or the tissues or the organs together
- provides support to the organ and body
What are the components of CT?
Extracellular matrix
- fibers
- ground substances
Glycosaminoglycans
Proteoglycan
Glycoprotein
Cells:permanent and wandering cells
What are the examples of permanent cells?
- fibroblasts
- Adipocyte
- macrophages
- mast cells
What are the examples of wandering cells?
- lymphocytes
- plasma cells
- neutrophils
- eosinophils
- Basophils
- monocytes
Where are fibroblasts and adipocytes found?
Fibroblasts and adipocytes are found in the mesenchymal cell and remain fixed in that tissue for rest of its life
Where are macrophages and mast cells found?
Are found in the haemopoitic stem cells in bone marrow, circulate in the blood and move to the connective tissue
Where are the wandering cells found?
- originate from hemopoietic stem cell in bone marrow
- circulate in the blood
- they migrate from blood into connective tissue in response to specific stimuli
- later come back to the circulation
What are the characteristics features of the fibroblast?
- abundant cytoplasm (basophilic) and irregularly branched
- nucleus is ovoid, large, pale stained
- prominent nucleolus
What is the functions of the fibroblast?
- synthesize the fibers and ground substance
- fibroblasts also produce growth factors
What are the characteristic features of macrophages?
- very irregular surface
- oval or kidney shaped nucleus
- from bone marrow——monocyte——circulate in blood——enter in tissue as macrophage
What is the function of the macrophages?
- defense - phagocytosis of foreign substances, bacteria, dead cellular debris
- immunological - process the antigen from phagocytes materials and present that antigen to lymphocytes
What are the characteristic features of plasma cells?
- large ovoid cells
- juxtanuclear pale area - golgi complex and centrioles
- nucleus - eccentric, clock face appearance due to heterochromatin clumps
- derived from B-lymphocytes
What is the function of the plasma cells?
- immunological - synthesize antibodies in response to antigen presented by macrophages
What are the characteristic features of mast cells?
- abundant basophilic secretory granules containing chemical mediator for allergic reactions
What is the function of mast cells?
- defense - synthesis and secretion of chemical mediators in response to allergic reactions
Where are adipose cells found?
- originate from local mesenchymal cells
- storage of lipids, large depot of energy and heat
What are the two types of adipocytes?
- unilocular fat cell (white adipose tissue), signet ring appearance
- multilocular fat cell (brown adipose tissue), common in newborns (abundant mitochondria)
What are the CT matrix components?
Fibres (protein fibers)
- collagen fibers
- reticular fibers
- elastic fibers
Ground substances
- glycosaminoglycan (GAGs) - carbohydrates (repeating disaccharides units)
- proteoglycan - protein + carbohydrates
- glycoproteins - carbohydrates + proteins
How are fibers made?
Fibroblast synthesizes protein molecules——protein polymerize to form fibrils——bundles of fibrils——fibers
What are the three types of connective tissue fibers?
- collagen fibers - polymerization of collagen 1 and collagen 2 proteins
- reticular fibers - polymerization of collagen 3 proteins
- elastic fibers - composed mainly of elastin protein
Importance - the predominant fiber is responsible for the specific functional properties of that connective tissue
What is the synthesis of fibers?
- alpha chain (polypeptide)
- collagen molecule as triple helix
- collagen molecule
- packing of collagen molecules (polymerization)
- fibril (shows bandings)
What are the characteristics of collagen fiber?
• Collagen is the most abundant protein in human body.
• Collagen fibres are the bundles of collagen fibrils.
• Collagen-I protein fibres are widely distributed & is the strongest one, present in bones, tendons, capsules of organs, dermis.
• Collagen-II protein fibres are present in cartilage.
• Collagen fibres are not branching like reticular or elastic fibres.
• White in appearance (macroscopic)
• Acidophilic stain
• In dense CT, collagen bundles appear as
wavy structure
What are the characteristics of reticular fibers?
• These are collagen-III fibrils.
• Common in haemopoitic & lymphatic tissue.
• Fibrils are thin, branching & extensive network.
• Typically, collagen-III do not bundle to form thick fibres.
• Argyrophilic: Stains black with silver salt stain.
• In H&E stain it is not visualized.
➢ Reticular cells partially cover the fibres & ground substances.
➢ The resulting cell-lined trabecular system creates a sponge-
like structure within which other cells & fluid are freely mobile.
What are the characteristics of elastic fibers?
• Elastic fibres predominate in dermis, elastic cartilage, lung, large artery.
• Major component is elastin protein. (produced by fibroblasts, endothelium, smooth muscle, and airway epithelial cells)
• Macroscopically yellowish in color.
• Thinner than collagen fibres & arranged in branching
pattern.
• Elastic fibres allow the tissues to respond to stretch &
distension.
• Elastic fibres are poorly stained with eosin in H&E stain & appear somewhat refractive.
• Special dye, orcein or resorcin-fuchsin stain elastic fibres
selectively.
How can elastin molecule stretch and recoil?
Elastin protein molecules are in extensive cross-linked network
What are ground substances?
• Fills the space between the cells & the fibres.
• Colourless & transparent
• It is highly hydrated, can imbibe a large volume of water.
• It is viscous (jelly-like) & acts as both a lubricant & a barrier to the penetration of invaders like foreign bodies, bacteria.
What are the three major components of ground substances?
• Glycosaminoglycans (GAGs): e.g., Chondroitin sulfate, Keratan sulfate, Heparan sulfate, Dermatan sulfate, Hyaluronic acid
• Proteoglycans: e.g., Aggrecan, Syndecan
• Glycoproteins: e.g., Fibronectin, Laminin
What are GAGs?
• Glycosaminoglycans (GAGs) are polysaccharides & are formed by linear chains of disaccharide units. (unbranched polysaccharide chain made of repeating disaccharides)
• Because of abundance of hydroxyl, carboxyl & sulfate groups in the chain, these are intensely hydrophilic.
• Except for hyaluronic acid, these linear chains are bound to a protein core forming the proteoglycans.
• Hyaluronic acid (Hyaluronan) is a slippery substance. They make linear aggregations of
proteoglycan monomers & increases the viscosity. Bacteria that produce hyaluronidase
enzyme have great invasive power.
What are proteoglycans?
(80-90% GAGs+10-20% Protein)
• GAGs are bound to a protein core forming proteoglycans (Test tube brush pattern).
What are glycoproteins?
• These are polypeptide chain, attached with it are the branched chains of monosaccharides.
• They have the multiple adhesive sites, that play the important role in the interaction between cells, adhesion of cells to their substrate.
What are the functions of connective tissues?
• Connects & binds cells, tissues, organs (tendon, intercellular matrix).
• Structural support of organ, & body (capsule & stromal tissue, skeleton).
• Defense & protection (phagocytosis, antibody)
• Medium for exchange of nutrition & metabolites (matrix is the medium through
which nutrition & metabolic wastes are exchanged with blood vessels).
• Energy reservoir & heat production (adipose tissue)
• Control the growth & differentiation: Fibroblast synthesize protein, it also produces
growth factors to influence the cell growth & differentiation.
What are the three basic components that are needed for classification?
cells, fibers, ground substances) are constant in all types of CT.
CT are classified depending on
– which component is predominating. – Its functional aspect.
What is the CT proper?
– Loose CT (also called as areolar tissue)
– Dense CT: (2 types) Regular & irregular dense CT
What is the specialized CT?
– Cartilage
– Bone
– Adipose tissue
– Blood
– Hemopoietic tissue – Lymphatic tissue
What is the embryonic CT?
– Mesenchyme
– Mucous CT
What is loose connective tissue?
• More ground substance
• Cells are mostly fibroblasts & macrophages
• Supports the lining epithelium that are normally under pressure & friction (submucosal & subcutaneous CT).
-Forms a layer that sheathes the blood vessels.
What is dense connective tissue?
• Predominance of collagen fibers & very few cells.
• Less flexible & more resistant to stress
What are the two types of dense CT?
•
Two types of dense CT
Dense regular: collagen bundles are arranged in
regular pattern.
– They offer great resistance to stresses in longitudinal direction.
– Example: tendon, ligament.
Dense irregular: bundles of fibers are irregularly
arranged.
– Offer great resistance to stresses in all direction.
– Example: dermis.
What is the adipose connective tissue?
• Special type in which adipose (fat) cells predominate.
• Unilocular or white adipose tissue, signet ring appearance of the cells
• Multilocular or brown adipose tissue, more in newborn
• Storage & mobilization of lipid: large depot of energy.
• Brown adipose tissue produces more heat.
What is embryonic connective tissue: mesenchyme?
• Found in the embryo
• Abundance of thick ground substance
• Reticular (collagen) fibers: Very fine & sparse.
• Mesenchymal cells: Small, spindle- shaped, uniform cells with multiple processes
What is embryonic connective tissue: mucous connective tissue?
• Present in umbilical cord as Wharton’s jelly
• Gelatin-like ground substance
• Reticular (collagen) fibers: Very
fine
• Spindle-shaped cells are widely separated & appear like fibroblasts
