epithelial tissue

where does epithelial tissue originate from

3 germinal layers

what does ectoderm line

epidermis

what does mesoderm line

lining of uterus system

what does endoderm line

lining of gastrointestinal tract

function of epithelial tissue

protective barrier, selctive diffusion, absorption, sensory, glandular secretion

apical domain features

cilia stereocilia, microvilli

Microvilli features and adaptations

finger like cylindrical , with actin filament core

increase surface area

cilia features, origin and functions

• long cytoplasmic process, motile, axoneme core made of microtubules in 9+2 arrangement

• respiratory tract epithelium, female reproductive tract, flagella, brain ependyma

• flow of fluid over epithelium, movement of sperm

stereocilia feature and origin

• long, immotile, actin filaments, no axoneme

• male reproductive tract, inner ear

lateral feature - occluding and tight junctions

• seal between two membranes, protein interaction between claudin/occludin

• A separate apical domain from basolateral domain

• gated barrier

lateral feature- anchoring/adherens

• zonulae adherens- circumferal belt around apical domain, actin filaments

• fascia adherens-not around whole circumferance, ribbon like, in epithelial and cardiac tissue

• Macyla adherens-punctuate like junctions, keratin filaments

hemidesmosomes

attatches basal surface of epithelial cell to basement membrane

Lateral feature - communication/gap junction

-selective diffusion of molecules and direct cell to cell communication

• six channel protein connexins form connexon

• two connexons form gap junction

interdigitations and their adaptations

finger like structures to increase surface area for ion channel protein insertion

what is a basement membrane

layer of extracellular material beneath epithelial cell that separates connective tissue from epithelial tissue

basement membrane two types and their components

• basal lamina- beneath epithelial cell (laminin, collagen IV)

• reticular lamina (type III collagen)

fused basement membrane + function

when two neighbouring basal lamina fuse

• structural support, anchoring, tissue repair and regeneration

hemidesmosomes are present as what types

type 1 - complex (stratified and pseudo stratified)

type 2- simple

in H junction what is present inside inner cytoplasmic plate and outer membrane

ICP- keratin intermediate filaments

AOM-laminin, a6b4

simple squamous - where, feature, function

• endothelium, mesothelium, bowmans capsule

• single layer of flattened cells and nuclei

• gas exchange, lubrication, fluid transport

where are endothelium or mesothelium found

endo- lining of blood vessels and heart

meso- body cavities

single cuboidal (feature, origin, function)

• kidney tubules

• single layer of cuboid like cells, large spherical central nucleus

• secretion, absorption, protection

simple columnar (o,f, f) CILIATED OR NON CILIATED

• NON CILIA- lines digestive tract

• CILIA- lines uterus and bronchitis

• single layer of column shaped cells with oval nucleus at base

• secretion , absorption, protection, enzyme secretion

pseudostratified columnar CILIA AND NON CILIATED

• NON CILIA- ducts of male reproductive tubes

• CILIA- lines trachea

• varying nucleus heights and apical domain, goblet cells and cilia

• protection, lubrication, mucous secretion

stratified squamous KERATIN OR NOT KERATINIZED

• protects underlying cells from abrasion, acts as a barrier against pathogens

• no hair- 5 layers, hair-4 layers

• non keratinized- superficial, basal, intermediate

• nuclei are more visible at top layer

transitional epithelium (o, f)

• uterus, urinary bladder

• stretches and permits distension of urinary bladder

3 types of epithelium specialised

• sensory, pigmentary, spermatogenic

what are two types of transport through epithelia and describe

• transcellular- requires channel or carrier proteins

• paracellular- occurs through zonulae adherens, water and electrolytes

unicellular cells of glands types

goblet cells and neuroendocrine cells

describe goblet cells feature and origin

• located in simple columnar, pseudostratified epithelium

• secretes mucous

• nucleus located at basal layer

• digestive and respiratory tract

3 types of secratory products for exocrine glands

mucous, mixed, serous

3 types of exocrine secretions and features

• merocrine- vesicle +exocytosis

• apocrine- apical domain removed

• holocrine-undergo programmed cell death, discharged to lumen of gland, replaced by differential stem cells