Textus epithelialis Štěpán Jelínek Epithelial tissue Textus epithelialis Štěpán Jelínek

Characteristic of epithelium cells foundation is basal lamina minimum of extra cellular matrix plenty of intercellular junctions various shapes – important for classification variability of functions

Basal lamina thin layer of extracellular matrix two layers collagen IV. type, laminin, proteoglycans two layers lamina rara, lamina densa lamina reticularis – part of connective tissue foundation for epithelial cells produced by epithelial, muscular, Schwann‘s cells and adipocytes

Basement membrane two connected basal laminae on the border of two epitheliums lung, kidney two laminae rarea, one lamina densa basal lamina and lamina reticularis visible in light microscope PAS positive

Function of basal lamina barier selection in transport - proteoglycans selection of cells – laminin regeneration wound healing, NM junction polarisation and migration of epithelial cells

Polarity apical part of cell basal (basolateral) part of cell lumen of organ, surface of organ basal (basolateral) part of cell basal lamina in contact with lamina propria

Lamina propria contains vessels and nerves mechanical support of epithelium connects epithelium to another layers usually undulated surface - papillae

Specialisations of cellular surface free surface microvilli, stereocilia, cilia lateral surface intercellular junctions, interdigitations basal surface connection with BL, basolateral labyrinth

Microvilli, stereocilia, cilia non-branching projections of cell enlargement of cell surface stereocilia branched non – motile projections cilia non-branching motile projections transport of extracellular mass

Intercellular junctions adhesive zonula adherens (belt desmosome) desmosome (macula adherens) hemidesmosome occluding zonula occludens (tight junction) communicating gap junction (nexus)

Intercellular junctions (belt) Zonula occludens cell. membranes without intercell. space five layers of membrane Zonula adherens intercell. space about 20 nm thicker membrane connected with cytoskeleton

Intercellular junction (spot) Desmosome intercell. space about 30nm sometimes dark plate connected with cytoskeleton hemidesmosome connection between cell and BL Nexus (gap junction) intercell. space about 2 nm connexons – forms pores for ion transport

Regeneration of epithelium fast and complete faster with complete BL continual regeneration of cells stem cells small intestine – 3 days skin - 27 days

Types of epithelial cells transporting cells signalising cells synthesizing and exporting cells myoepithelial cells stem cells

Transporting cells cells transporting ions (active) microvilli, basolateral labyrinth prox. a dist. tubule of kidney, striated ducts of sal. gl. cells transporting using pinocytosis transport of larger molecules pinocytic sacs endothelium

Signalising cells release signal molecules neurocrine cells (neurons) distribution across synapse paracrine cells (DNES) distribution – diffusely to ECM secretory granules in basal part of cell endocrine cells (suprarenal) distribution - transport by blood stream ultrastructure depends on type of substance

Synthesising and trasporting cells proteins synthesis, modification, storage serous cells of sal. gl., serous cells of pancreas glycoproteins of mucus mucus (lighter than cells prod. proteins) mucous cells of sal. gl., goblet cells steroids lipid droplets, sER, tubular MIT

Myoepihelial cells cytokeratins, contractile microfilaments acins and tubules of sweat, salivary, lacrimal gl.

Stem cells maternal undiferetiated regeneration of epithelium

Classification of epitheliums acording to spatial arrangement flat trabecular reticular according to function

Flat epithelium according to count of layers simple stratified pseudostratified, transitional according to shape of cells squamous cuboidal columnar keratinised and non-keratinised

Single layered squamous

Single layered cuboidal

Single layered columnar

Single layered columnar with cilia

Pseudostratified with cilia

Stratified squamous

Transitional

O2 – muscular artery

O1 - kidney

O3 – thyroid gland

O4 - colon

O5 – uterine tube

epidydimis

O6 - esophagus

O7 - skin

V10 - trachea

O8 – urinary bladder

Trabecular epithelium cells in cords cords form web between cords are capillaries, nerves liver, adrenal, pituitary

E8 - adrenal AZAN

Reticular epithelium cells are in contact only with their processes cells form web in „holes“ of web are other cells thymus, bone marrow

Classification according to function epithelium covering - skin epithelium resorbtional - intestine epithelium respiratory - lung epithelium sensory – olfactory ep. epithelium muscular – myoepithelial c. epithelium germinal – testes epithelium secretory - glands

Glandular epithelium cells producing and releasing substrate this substrate is used by organism type of secretion merocrine (pancreas) apocrine (mammary gland) holocrine (sebaceous gland)

Types of gland exocrine endocrine excretion to lumen of organ have ducts endocrine do not have ducts excretion to blood capillaries

Types of exocrine glands according to shape of secretory and excretory parts simple glands compound glands tubular alveolar (acinar) tubulo-acinar

O9 – glandula sublingualis

O10 - pancreas

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