CONNECTIVE TISSUE Flashcards
What are the characteristics of connective tissue?
They have large amount of ECM
cells are widely separated
Connects the cells, tissues and organs together
Provides support to the organ and body
What are the components of CT?
Fibres (collagen, reticular, elastic), ground substances which consist of glycosaminoglycans, proteoglycan, glycoprotein and cells which can be permanent or wandering.
What are the permanent cells present in CT
Fibroblasts, adipocyte, macrophages, mast cells
What are the wandering cells
Lymphocytes, plasma cells, neutrophils, eosinophils, basophils, monocytes
Where do fibroblasts and adipocytes locate from?
Mesenchymal cells
Where do macrophages and mast cell originate from?
Haemopoitic stem cells in bone marrow
State characteristic features of fibroblasts
Is the principal cell of connective tissue. Has abundant cytoplasm and is irregularly branched. Nucleus is ovoid, large and pale stained with a prominent nucleolus
What is the fxn of fibroblasts
Synthesize the fibres and ground substances and growth factors.
What is the feature of macrophages
Irregular surface with an oval nucleus.
What is the fxn of macrophage
Phagocytosis of bacteria, dead cell debris and foreign substance
Processes antigen and presents to lymphocytes
What is the feature of plasma cells
Large ovoid cells derived from B-lymphocytes with a spherical eccentric appearance due to heterochromatin clumps
What is the function of plasma cells
Synthesizes antibody in response to antigens presented by macrophages
What is the feature of mast cells
Abundant basophilic secretory granules containing chemical mediators for allergic reactions. (Histamine, heparin, proteoglycans, ECF-A, SRS-A)
What is the fxn of mast cells
Synthesis and secretion of chemical mediators in response to allergic reaction.
What is the function of adipocytes cell
Storage of lipids, large storage of energy and heat
What are the two types of adipocytes
Unilocular fat cell which is a white adipose tissue with a signet ring appearance
Multilocular fat cell which is a brown adipose tissue which is common in newborns and is a bundant in mitochondria
How are fibres formed?
Alpha polypeptide chain arranges to form a collagen molecule as triple helix, the collagen molecules polymerise to form fibrils. The fibrils bundle up to form fibres
What are the characteristics of collagen fibres
Most abundant proteins in the body
Collagen 1 fibres are the strongest and present in bones tendons, capsules of organs, dermis
Collagen 2 fibres are present in cartilage
The fibres have high tensile strength and low elasticity.
Explain appearance of collagen fibres
White in appearance, acidophilic stain.
What are the characteristics of reticular fibres
Made of collagen 3 fibres and are common in haemopoitic and lymphatic tissue
Fibrils are thin, branching and extensive network and do not bundle to form fibres
What is the appearance of reticular fibres under microscope
They are agyrophilic, stains black with silver stain.
In H&E stain is not seen.
What are the characteristics of elastic fibres and where are they found
Predominant in dermis, elastic cartilage, lung, large artery
Elastic fibres allow tissues to respond to stretch and distension
Stretch and recoil
What is the appearance of elastic fibres under microscope
Macroscopically yellowish in colour
Arranged in branching patterns
Elastic fibres poorly stained with eosin in H&E stain
Special dye, orcein, resorcin-fuschin stain elastic fibres selectively
Elastin protein molecules are in extensive cross-linked network
Explain main characteristics of ground substances
Colourless and transparent jelly like liquid that is highly hydrated and holds a lot of water that acts as both a lubricant and a barrier to the penetration of invaders like foreign bodies and bacteria
Explain glycosaminoglycans in ground substances
Glycosaminoglycans are unbranched polysaccharides
They are hydrophilic bc of abundant hydroxyl, carboxyl, sulfates in chain
Linear chains are bound to protein core forming proteoglycans except hyaluronic acid
Explain proteoglycans
GAGs are bound to a protein core forming proteoglycans
Explain glycoproteins structure and function
Are polypeptide chains attached with branched chains of monosaccharides
They have multiple adhesive sites that play the important role in the interaction between cells and adhesion of other cells to their substrates.
What are the functions of CT
Connects and bind tissues, organs, etc
Structural support of organ and body
Defense and protection
Medium for exchange of nutrients and metabolites
Energy reservoir and heat production
What are the components of loose connective tissue
Ground substance, cells are mostly fibroblasts and macrophages
What is the fxn of LCT
supports the lining epithelium that are normally under pressure or friction
Forms a layer that sheathes blood vessels
What are the characteristics of dense connective tissue
Collagen fibres dominanr and very few cells
Less flexible and more resistant to stress
Explain dense regular connective tissue structure
Collagen bundles are arranged in regular pattern
Explain function of dense regular connective tissue and give examples
Great resistance to stresses in longitudinal direction, example : tendon and ligament.
Explain structure of dense irregular connective tissue
Bundles of fibres are irregularly arranged
Explain function of dense irregular connective tissue and give an example
Offere great resistance to stresses in all direction, example : dermis.
Explain embryonic connective tissue structure (mesenchyme)
Mesenchymes found in embryo are abdundant in thick ground substance with very fine and sparse reticular collagen fibres
Explain the structure of mucous embryonic connective tissue
Gelatin like ground subtance with very fine reticular collagen fibres. They are spindle shaped.
