cytology connective tissues Flashcards
What are the functions of the connective tissues?
- Provide a structural matrix, that supports and connects tissues and cells, forming body organs
- Interstitial fluid allows the exchange of nutrients and waste between cells and the blood supply
What is the major components of the connective tissue?
- Extracellular matrix
which insludes protein fibres, Ground substances, Water
What do the differences in the composisiton of cells, fibers and ground substances create?
They create a structural and functional variability across the connective tissue types
Where do connective tissues originate from?
- Embryonic mesenchymne
What is the structure of mesenchymal cells?
- They are undiferentiated cells with a large nuclei and spindle-shaped cytoplasmic extensions
Name types of connective tissues
- Soft connective tissues proper
-specialsied types( bone, cartilage)
What are the most common cells in connective tissue proper?
Fibroblasts
What are the roles of fibroblasts?
- Proudcing and maintaning ECM components including:
-collagen
-elastin - Ground substances
-The ECM compoents are synthesisied and secreted by fibroblasts and then further modified outside the cell to form the matrix
Name the 2 cell states of fibroblasts
- Active fibroblasts
- Quiescent fibroblasts(fibrocytes)
Explain the strutcure of fibroblats in an Active fibroblast state
- Larger with abundant cytoplasm and irregular branches
-Contain a lot of RER and well developed Golgi Apparatus - Nucleus is large,eurochromatic, with a prominent nucleolus
Explain the structure of Quiescent fibroblasts
- Smaller, spindle-shaped with fewer cytoplasmic processes
- Less RER darker heterochromatic nucleus
What are adipcoytes also known as?
Fat cells
What are adipocytes dervived from?
Mesenchymne
Where are adipocytes found?
Connective tissues of verious organs
What are the functions of Adipocytes?
- Energy storage: They store lipds for metabolic use
- Cushioning + insulation:Protect and insulate skin and internal organs
What is the functions of Macrophages
-Specialize in phagocytosis
-Secrete growth factors critical for tissue repair and regeneration
-Play a role in antigen processing and presentation for lymphocyte activation.
-Abundant at sites of inflammation and involved in tissue repair.
What are the characteristics of Macrophages: Nucleus, surface and Cellular structure
Nucleus:
- Oval or kidney shaped
Surface:
- Irregular with pleats and protrusions, aiding pinocytotic and phagocytic activity
Cellular Structure:
- Contains well developed Golgi Apparatus and
many lysosomes
Where do Macrophages orgiinate from?
Originate from monocytes circulating in the blood.
Monocytes migrate into tissues, where they differentiate into macrophages.
Where do Monocytes form?
-Monocytes form in the yolk sac during early embryonic development and become part of the mononuclear phagocyte system
What do macrophages do in response to inflammation?
- Increase in size and protein synthesis
- Recruit additional monocytes from bone marrow
What is the structure of Mast cells?
- Oval or irregularly shaped
- Contains Basophillic secretory granules which change the colour of basic dyes from blue to purple/red due to sulfated GAGs
What is the function of Mast cells?
They release bioactive substances invloved in:
-Local inflammatory responses
- Innate immunity
-Tissue repair
Name some examples of the molecules released from Mast cells?
-Histamine
-Chemotactic factors
-Cytokines
Where are Mast cells found near and where are they located
-Found near small blood vessels in skin and mesenteries
-Located in tissues lining the digestive and respiratory tracts
What is the role of Mast cells in hypersensitivity?
- They trigger immediate hypersensitivity reactions
Explain the process of Mast cells in hypersensitivity reactions
- First exposure to an antigen produces IgE antibodies
- IgE antbody binds to mast receptors
- Upon 2nd Exposure, atigen - IgE interaction, triggers rapid degranilation
- Degranulation leads to sudden allergic reactions
Where are plasma cells derived from?
lymphocytes
What is the function of plasma cells?
- Specialised in producing antibodies
What is the structure of plasma cells?
- Large, ovoid cells with basophilli cytoplasm rih in RER
- Contains a large Golgi Apparatus near the nucleus
What is the structure of the Nucleus in plasma cells?
- Spherical
shows regions of heterochromatin with lighter eurohromatin
Where are plasma cells found?
Connective tissues
What is the lifespan of plasma cells?
short lived
only 10-20 days
What are leukocytes known as?
White blood cells
What happens to leukocytes during inflammation
The number of them increase
What do leukocytes do in migration
- They exit the bloodstream by migrating between endothelial cells
What is the lifespan of leukocytes?
- few hours or days
Explain the inflammation process in leukocytes
-Triggered by the release of chemical mediators from cells, ECM, and blood plasma proteins.
Leads to:
Increased blood flow and vascular permeability.
Activation of macrophages for phagocytosis.
What are fibres made from
proteins
Name the different types of fibres?
- collagen fibres
- Reticular fibres
- Elastic fibres
What is the function of collagen fibers?
Provide strength and support
What are reticular fibres made out of?
Collagen
What are elastic fibres composed of?
- elastin
How many types of collagen fibres are there?
28
Name the three ways collagen fibres are categorised
- Fibrillar collagens
- Network or sheet forming collagens
-linking/anchoring collagesn
Name the types of collagen in fibrillar collagens
Type: 1,2,3
Name the types of collagen found in Network or sheet forming collagens
- Type IV = 4
Name the type of collagen found in anchorning/linking collagens
- VII
= 7
What colour does eosin turn collagen?
Pink
What colour does Mallory Trichrome turn collagen fibres?
- Blue
What colour does Sirius red turn collagen?
- Red
Where is type 1 collagen found and what does it form
- Tendons, dermis,bone
- Forms Large fibrils and fibers
What does type 2 collagen form
Fibrils but not fibers
What does type IV collagen form
- Sheet like networks
What is proline and lysine hydroxylated by in collagen synthesis?
hydroxylase enzymes and reuires oxygen, fe 2+ and vitamin C
What is the function of proteoglycan and collagens?
- Stabilise fibrils
What are reticular fibres composed of
Type 3 collagen
Where are reticular fibers found
Reticular lamina of basement membrane
What structures does the reticular fibers surround
Adipocytes,smooth muscles ,nerve fibers,small blood vessels
What is the structure of elastic fibers?
- Cross linked by desmosine rings
What is elastic fibers composed of ?
- Fibrillin microfibrils and telastin
Where is elastin fibres found?
- Found in tissues
- large arteries
Explain the elastic property of elastic fibres and its function
- They have a rubber like elasticity
- This allows tissues to stretch and return to their shape
What does elastic fibres stain well with?
- Orcein and aldehyde fuchsin
What are ground substances?
- Highly hydrated, ECM component that fills space between cells and fibers in connective tissues
What is the role of ground substanes?
- Facilitates diffusion
- Acts as a lubricant
- And acts as a barrier
What are the major components in ground substances
- GAGs
- proteoglycans
-Water and interstitial fluid - Multiadhesive glycoproteisn
What is the structure of GAGs and function
- Long negatively chared polysaccharides
- Provide lubrication,cushioning
What does proteoglycan conatin?
- A core protein with covalently attached GAGs
What is the role of Multi adhesive glycoproteins?
- communication and adhesion
What does water contain and what is its role?
- water and ions
- Acts as a medium for nutrient and waste exchange
What does reticular tissue contain?
- Type 3 collagen fibers
- macrophages and dedritic cells
what is the function of reticular tissue?
- Provides a specialised microenvironment for cells
- creates a netwrok that facilitates the passage of leukoytes and lymph
Where is mucoid tissue found?
- Fetal umbilical cors
What does mucoid tissue contain?
- Sparse collagen fibers and scattered fibroblasts
- and mesenchymal stem cells
What is connective tissue proper divided into ?
- loose and dense
Where are loose connective tissues found
beneath epithelial linings of organs
What does loose connective tissue contain
- Fibroblasts
- collagen elastic and reticular fibers
What is a property of loose connective tissue
- flexible
Name the 2 types of dense connetive tissue types
dense irregular
dense regular connetive tissue types
Where are deep irregular connective tissues found?
- Deep dermis and organ capsules
Where are dense regular connetive tissues found?
- Tendons
-Ligaments
-Aponeurons
How are are the collagen fibers alligned in dense iiregular connective tissue
- Arranged randomly forming a 3D network
How are the collagen fibers alligned in Dense regular connective tissue
- Parallel bundles
What is Edema
- excessive accumulation of interstitial fluid in connective tissue in the connective tissues
What is Marfan syndrome formed from
- Mutations in the fibrillin geene
What are keloids caused by
- Abnormally large amounts of collagen that form scars of the skin
