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Epithelia - Coggle Diagram

- - - - predominantly ground substances
      - multiple cell types
      - collagen fibres are thin and sparse
    - - oxygen and nutrients from small vessels
      - carbon dioxide and metabolic waste to small vessel
    - - contains immune cells, sometimes permanently found there
      - more cells in areas exposed to pathogens (gut and respiratory)
      - can swell
- - - - width>height
      - central nucleus
      - plate like
      - example- endothelia line blood vessels
    - - height=width
      - central nucleus
      - isodiametric (roughly spherical)
    - - height>width
      - basal nucleus
  - - - one layer, so all in contact with BM
      - involved in diffusion, absorption and secretion
    - - multiple layers
      - form protective surface
      - may contain more than one cell type
    - - appear multilayer, but only one cell thick
      - all cells touch BM but not all touch lumen
  - - - cilia
      - microvilli
    - - keratinised (cells on top surface have no nucleus)
      - non-keratinized
  - - - simple squamous
    - - selective exchange of nongaseous material, in digestion and kidney
    - - non-transporting but move fluid across tissue fluid
      - found in respiratory and female reproductive tract
    - - stratified
      - found in skin, mouth lining, pharynx, oesophagus, urethra and vagina
- - - - large nucleus
      - abundant RER
      - electron dense vesicle
    - - flatten nucleus
      - developed Golgi
      - secretory vesicles at cell apex
    - - developed SER
      - abundant mitochondria
      - lipid in vacuole
- - - - collagen, elastin, ground substance components synthesis when stretched
    - - synthesises fibres and ECM
      - involved in wound healing
      - have gap junctions but no basal lamina
    - - secrete cartilage ECM
    - - secrete bone ECM
    - - lipid storage, hormone and growth factor synthesis
    - - phagocytic cells
    - - involved in immune response
      - found in connective tissue and mucous membranes
      - involved in secondary response and release granules with substances that promote inflammation
    - - give rise to differentiated cells
      - help in growth and repair for neo-vasularization
  - - - found in lamina propia of respiratory and GI tract
      - immune response
    - - produce antibodies
    - - phagocytosis
    - - allergic reaction
    - - develop into macrophages
    - - similar to mast cells (immune response)
- - - - they have a plasma membrane
      - bundles of microtubules
      - has 2 central microtubules surrounded by microtubule doubles
    - - can penetrate
      - move substances over their surface
    - - inner and outer hair cells
      - the outer hair cells have 3 rows
      - contains acin
      - sound causes bending which causes epithelia to react and change shape, this sends signals to inner hair cells then to brain
  - - - they do not move
      - although the cytoplasm does
      - the F-actin runs entire length adn has capping proteins
      - actin attached to plasma membrane by lateral arms
      - F-actin filament binding proteins bundle teh microfilaments and link them to plasma membrane
- - - - Found near apical surface
      - selectively maintain a seal between epithelial cells
      - form a collar around each cell to block passage of contents between cells
    - - adheres to actin filaments
      - attach cells by cytoskeleton so provides strength
    - - attaches by cytoskeleton so provides strength
      - adheres to intermediate filaments like keratin
    - - allows communication via small substances
      - gap junction proteins are called connexions
  - - - linked to intermediate filaments
    - - actin-linked
    - - provide strength
- - - - in contact with external environment
      - has down growth (for epidermal appendages-hair) and a series of rete ridges (protects from shearing stress)
      - has 4 cell types
        
        Keratinocytes
        
        contain keratin intermediate filaments
        
        place melanin granules above melanocytes' nuclei to protect from damage
        
        Melanocytes
        
        contain melanin
        
        when they move into the dermis it causes melanoma
        
        Langerhans cells
        
        immune system (communicate with T cells via leaving epidermis)
        
        Merkel cells
        
        attached to sensory nerve endings
      - has 4 cells layers
        
        basal
        
        cuboidal or low columnar, mitosis
        
        spinous
        
        cells move up tightly bound
        
        granular
        
        loose nucleus, secrete lipids and change membrane composition
        
        cornified
        
        tightly packed, flattened, dead cells
        
        cornified envelope (crosslinked protein layer under membrane) and lipids form epidermal layer
    - - Papillary dermis
        
        less collagen and elastic fibrils arranged vertically
        
        more glycosaminoglycans and small capillaries
      - Reticular dermis
        
        dense collagen and thick elastics fibres arranged horizontally
        
        major blood vessels and lymphatic vessels
    - - deepest layer of skin
      - mainly composedd of adipose tissue and collagen fibres
      - contains some epidermal appendages and major blood supply and nerves