Epithelia Tissue Flashcards by Nina Nguyen

Features of Epithelia Tissue

arranged in continuous sheets (single or multiple layers)
held together by cell junctions
- tight, adherens, gap, desmosomes, hemidesmosomes

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Basement Membrane

found between the epithelium and connective tissue

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Components of Basement Membrane

Basal Lamina, Reticular Lamina

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Basal Lamina

secreted by epithelial cells

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Reticular Lamina

produced by the cells of the connective tissue (fibroblasts)

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Function of the Basement Membrane

supports epithelium, physical barrier, filtration of substances in kidney, provides surface for epithelial cells to migrate during growth and wound healing

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Types of Epithelial Tissue

Covering + Inner lining and Glandular

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Covering and Lining Epithelia (breakdown)

outer covering = protects skin and some internal organs
inner lining = blood vessels, interior systems (respirator, urinary, digestive and reproductive)

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Classification of Epithelia Tissue

arrangement + shapes of cells

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Simple arrangement

single layer (absorption, secretion, filtration)

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Stratified arrangement

2 or more layers (protective)

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Pseudostratified arrangement

multiple layers
- all cells in contact with the Basement Membrane

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Squamous shape

flat and thin (passage for diffusion)

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Cuboidal shape

as tall as they are wide (secretion, absorption)

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Columnar shape

more tall than wide (secretion, absorption)

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Transitional shape

cells can change shape depends on organs shape

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Glandular Epithelia (location)

found in the secretary portions of the gland

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Function of the Glandular Epithelia

produce and release secretory products

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Exocrine

produces sweat, tears, saliva, etc.
- secrete into ductal system

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Endocrine

releases hormones into the bloodstream
- controls mood, growth and development

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Simple squamous (function)

filtration in kidney, diffusion in lungs and secretion

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Location of the simple squamous epithelial tissue

in the lining of blood vessels

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Sub-types of simple squamous

Mesothelium and Endothelium

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Mesothelium (location)

surrounds organs of the chest, abdominal cavity and pelvis

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Endothelium (location)

inner lining of blood vessels and lymphatic system

Glands consist of....

single cell or a group of cells that secrete substances into ducts, onto a surface or into blood

Simple cuboidal (location)

glandular tissue and kidney tubules

simple cuboidal (function)

absorption + secretion (mainly in ducts, pipes and tubes)

Simple cuboidal has...

apical cilia and microvilli

Simple columnar (location)

mainly in the digestive tract (absorption in intestine + secretion in stomach)

Simple columnar (features)

- more cytoplasms = more organelles - more metabolically active than squamous cells

Simple columnar (function)

secret mucus that protects surrounding surface from damage

Types of simple columnar

Ciliated vs. non-ciliated

Non-ciliated simple columnar epithelium

have goblet cells and microvilli - function = secretion and lubrication of mucus goblet cells

Ciliated simple columnar epithelium

have goblet cells - function = assists motility of mucus and foreign objects or oocytes

Stratified squamous (features)

multiple layers (can sustain damage)

Stratified squamous (location)

where mechanical/chemical stress are severe - Keratin will also be present

Keratin (function)

protein that helps form hair, nails and epidermis

Stratified squamous (sub-types)

Keratinised and non-Keratinised

Keratinised stratified squamous (location)

locate in skin

non-Keratinised stratified squamous (location)

locate in mouth, throat, tongue, oesophagus, anus and vagina

Stratified squamous (function)

protection from microorganisms and protection from water loss

Psuedostratified columnar (appearance)

looks like multiple layers but only comprised of a single sheet of cells

Psuedostratified columnar (featues)

all cells in contact with Basement Membrane but not all reach the apical surface of the tissue

Psuedostratified columnar (sub-types)

ciliated vs. non-ciliated

Ciliated psuedostratified columnar (consists of...?)

have cilia on some cells and goblet cells

Ciliated psuedostratified columnar (function)

secrete mucus from goblet cells

non-ciliated psuedostratified columnar (consists of...?)

no cilia and lack of goblet cells

non-ciliated psuedostratified columnar (function)

absorption and protection

Psuedostratified columnar (overall function)

absorption and secretion of mucus, protection from foreign particles, transporting materials (hormones + enzymes)

Microvilli (function)

increase SA to absorb more substances

Cilia (function)

move virus, bacteria and other unhealthy items up and out of the airway

Cytoskeleton

network of protein filaments and microtubules in cytoplasm

Cytoskeleton (function)

helps cells maintain their shape, internal organisation and involves in cell movement

Cytoskeleton (consists of...?)

microfilaments, intermediate filaments, microtubules

Microfilaments (location)

underneath cell membrane and cytoplasm

Microfilaments (function)

alter cell shape, link cytoplasm to membrane, tie cells together and muscle contraction

Intermediate filaments (function)

anchor cells together and provides strength against tension

Tight junction (key proteins)

claudins and occludins

Tight junctions (function)

keep cell polarity by preventing migration of proteins between apical and basal surfaces

Tight junction (location)

stomach, intestines, bladder

Adherens junction (key proteins)

cadherins and catenins

Adherens junction (features)

have a plaque layer of proteins to join actin to cadherins (through actin filament network)

Cadherins

span the gap/plaque

Catenins

link the Cadherins to Actin

Adherens junction (function)

prevents cell separation from tension forces

Desmosome junction (key proteins)

Cadherins, Desmoplakin and Keratin

Desmosome junction (features)

also have a 'plaque' like adherens junction

Desmosome junction (cadherins)

spans the gap and bind to desmoplakin (linker)

Desmosome junction (keratin)

spans one desmosome to the another on the other side of the cell (anchor)

Desmosome junction (function)

provides strong adhesion between cells

Gap junctions (components)

2 hemichannels make up gap junction - 6 connexIN protein molecules form connexON/hemichannel

Gap junctions (description)

direction connection between cells

Gap junctions (function)

allows exchange of ions, second messengers and small metabolites between adjacent cells

Hemidesmosome (key proteins)

Integrin, Laminin, Keratin

Hemidesmosome (Keratin)

linker protein - binds to Laminin in the Basement Membrane and Keratin intermediate filament in the cytoplasm

Hemidesmosome (function)

connects epithelia to Basement Membrane - links Keratin to Basement Membrane