Primary Tissue : CT Flashcards
Function of CT
- provide a matrix to support and physically connect other cells and tissue
- facilitates exchange of metabolites through diffusion via its interstitial fluid
Components of CT ( Cells and ECM )
1 cells
- fibroblast and fibrocyte
- mast
- plasma
- leukocytes
- adipocytes
- macrophages
2 ecm
- fibers ( collagen , elastic and reticular)
- ground substance ( GAG’s ,proteoglycans and multi-adhesive glycoproteins )
Origin of CT
- mesenchymal stem cells from embryonic mesenchyme
- from mesoderm
What is mesenchyme,characteristics and mesenchyme stem cells and characteristics
- embryonic CT of mesoderm origin. Can differentiate into CT and hematopoietic tissue
- few cells and sparse collagen but abundant ground substance
- cells of mesenchyme
- make up CT only and not hematopoietic
- large nuclei , prominent nucleoli and euchromatin
- spindle shaped
How to mesenchymal SC form CT
-they migrate from mesenchyme and enclose and penetrate developing cells
Fibroblast shape , characteristics and function
- spindle shaped
- synthesize and secrete ecm
- developed Protein synthesis machinery
- rarely undergo mitotic divisions
- basophilia
Fibrocytes function, characteristics and shape
- spindle shaped
- quiescent
- smaller and heterochromatin nuclei
- maintain ecm
What do growth factors do and their target
- target is fibroblast
- they stimulate growth and differentiation
- renew cell cycle
What are myofibroblasts and characteristics
- fibroblast specialized or involved in wound repair
- have developed contractile apparatus
Adipocytes function, characteristics and structure
- specialized for cytoplasmic storage of lipids
- thermal insulation and cushioning for organs
- mesenchyme derived
What is adipose tissue
-tissue with large populations of adipocytes
Macrophages function, structure and characteristics
- specialized for phagocytosis
- removal of dead cells and ecm debri
- antigen processing and presentation
- secrete growth factors and cytokines
- developed protein synthesis machinery
- irregular surface with cleats and protrusions for phagocytosis and pinocytosis
Macrophages derivation and how they get to CT
- bone marrow hematopoietic cells derivation
- monocytes precursor derivation which circulates in blood moves through Venule into CT
Mast cells function, structure and characteristics
- synthesize and secrete biologically active macromolecules
- developed protein synthesis machinery
- basophilic cytoplasm
- display metachromasia
Why do mast cells display metachromasia
Due to acidic radicals of their sulfated gags
Macromolecules secreted by mast cells
- heparin : anticoagulant
- histamine : increases Venule permeability , produces allergic reactions
- cytokines : proteins which regulate and direct activities of leukocytes
Location of macrophages and significance
- near blood vessels and in respiratory and digestive tract
- they act as sentinels in pathogen invasion
What is immediate hypersensitivity reaction and how does it occurs
-allergic reaction which happens minutes after individual is exposed to antigen they are sensitive to it binds to mast cells and promotes release of chemical which cause the reaction
Plasm cells function, characteristics and structure
- produce antibodies
- basophilic
- spherical nuclei
- lymphocyte derived
Leukocytes function, characteristics and structure
- comprises wandering cell population in CT
- lymphoid bone marrow derived
- accumulate at site if inflammation to mediate immune responses
What is inflammation and how does it occur and characteristics
- vascular and cellular response to injury or invasion by pathogens
- ecm cells and plasma proteins release chemical mediators which release chemical mediators that increase vascular permeability
- there is increased blood flow to site of inflammation
Fibers structure and types in CT
-elongated structures formed form polymerization of proteins formed form fibroblasts
- collagen
- elastic
- reticular
Collagen fiber property and use and type of structures formed
-can form numerous networks , sheets and fibers
- resistant to normal tear and shear forces
- most Abundant in body 30% dry mass
Fibril forming collagens, where found and functions
Type 1 : skin, tendon, bone / resistance to tension
Type 2 : cartilage / resistance to pressure
Type 3 : skin, muscle, blood / stroma to organs
Type 5 : skin, bone / Same as type 1
Type 11 : cartilage / same as type 2
Network forming collagen, where found and function
Type 4 : basement membrane / filtration , support epithelium
Type 10 : during endochondral bone formation / increase density of matrix
Anchoring collagen types, where found and function
Type 7 : epithelium basement / connects BL to RL
Type 9 : cartilage / binds proteoglycans and type 2
Type 12 : skin, tendon / interacts with type 1
Type 14 ( XIV ) : binds type 1 to 5 and 12
Reticular fibers structure and function
- dispersed network of collagen 3 forming an extensive network of thin fibers
- stroma of organs
Elastic fibers structure and function
- sparse network of bundles of collagen ( 1 ) surrounded by elsatin proteins
- allowing organs to be stretched and retain original shape
How are elastic fibers formed
-fibrillin proteins polymerize and form microfibrils which are surrounded by deposits of elastin proteins.
What makes elasticity of elastic fibers and how does it come about
-cross link between elastin fibers
- elastin molecules have lysin rich regions with interspersed hydrophobic domains of lysine and proline
- as elastin deposits on microfibrils Lysyl oxidase converts lysine amino groups to aldehydes and 4 oxidized lysines on adjacent elastin’s condense covalently to form desmosine ring which is the cross link
What is ground substance and components that makes it up
-highly hydrated transparent, anionic and hydrophilic complex mixture of
1 GAG’s
2 proteoglycans
3 multi adhesive glycoproteins
Functions of Groud substances
1 facilitate exchange of metabolites between CT and capillaries
2 fills spaces between cells and fibers in CT
3 lubricant
4 protective barrier
GAG structure
-long polymers of repeating dissacharride units
Hyaluronan structure and function
- longest GAG forming peri cellular network
- binds large amounts of water
Types of sulfates gag’s and function
1 chondroitin
2 keratan
3 dermatan
4 heparan
-covalently bind to a core protein and form proteoglycans
Where are proteoglycans found
-bound covalently at hyaluronan via core protein and gag’s bind to collagen covalently
Aggrecan structure
-has core protein covalently bonded to keratan and chondroitin sulfated GAG’s
Embryonic mesenchyme structure and function
-rich in hyaluronan and water providing wide spaces for cell migration
Multi adhesive glycoproteins structure and function
- large protein complexes with branching ogliosaccharides
- have multiple binding sites for cell integrins and ecm components to bind them together
Fibronectin structure and function
- has binding sites for collagen and gag’s forms insoluble fibrillar network in CT
- important for cell migration
What is the interstitial fluid in ground substance and properties
- water
- same ionic content as blood plasma
What is an Edema
-swelling of tissue due to interstitial fluid from blood during increased Venule permeability is trapped in it during inflammation
Two forces acting on water in blood to enter and leave CT
- hydrostatic : due to pumping of heart
- colloid osmotic : due to plasma proteins such as albumin
What happens to excess water in tissue
-it drains into lymphatic system and eventually returns into the blood
Types of CT and their sub-types
1 CT Proper
- dense regular
- dense irregular
- loose / areolar
2 embryonic CT
- mucoid
- mesenchyme
3 reticular
4 Special CT
- cartilage
- blood
- bone
- muscle
Criteria for naming CT and what produces the differences
1 major component
2 structural characteristic
-diff in composition and density of cells, fibers and ground substance
Loose areolar characteristics and functions and where found
- much ground substance
- many cells
- spare collagen
- supports microvasculature
- lamina propia beneath digestive tract
- delicate consistency and not very resistance to stress
Dense irregular CT structure, characteristics and function and where found
- abundance of collagen 1 interwoven in a random order
- resists stress from all directions
- few cells and little ground substance
- dermis of skin , capsules of organs
Dense regular CT function, characteristics and structure and where found
- little ground substance
- few cells parallel to CT
- abundance of collagen 1 aligned in a parallel manner
- resists stress pronlonged in one direction
- tendons
What are tendinocytes
-regions in CT In which fibroblasts extend their cytoplasmic extensions
Mesenchyme characteristics, structure and function and where found
- sparse undifferentiated cells
- sparse collagen and much ground substance
- has cells which differentiate into CT cells
- provides space conducive for cell migration
- embryonic CT
Mucoid CT function, structure and characteristics and where found
- mucous or Whartson’s jelly
- abundant ground substance and sparse collagen and cells
- viscous matrix
- cushions and supports blood vessels in fetal umbilical cord
Reticular CT characteristics structure function and where found
-abundance of collagen 3 forming a delicate extensive network of stroma to organs
Reticular cells
-modified fibroblasts which produce proteins for reticular fibers
