Epithelium Flashcards by Jessica Cheney

a group of cells that function together to carry out specialized activities

a tissue

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Epithelial tissue

Covers body surfaces and lines hollow organs, body cavities, duct , and form glands

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Connective tissue

Protects, supports, and bind organs, stores energy as fat, provides immunity (Cartilage, bone, blood)

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Selective transport in epithelium

diffusion, absorption, secretion

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Characteristics of epithelial tissue

Surface specialization
Arrangement of cells
Cell junctions

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Basement membrane allows for interaction between _____ and ____

epithelium and connective tissue

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T/F? Epithelium contains blood vessels

False

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Types of morphological apical surface specialization?

Microvilli, cilium, stereocilium

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Microvilli are most developed in which tissues?

Absorptive: intestinal epithelium, kidney tubules

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Characteristics of microvilli

Finger like (1-2 um) extensions of plasma membrane
Increase surface area

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Cell type where cilia are found?

Columnar cells in respiratory tract and oviduct

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Characteristics of cilia?

Motile surface projections (7-10 um/ able to distinguish with light microscope) involved in one way transport of materials

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Cytoskeleton of cilium

2 central microtubules surrounded by 9 doublets, provides scaffold for proteins (molecular motor)

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Symptoms of Ciliary dyskinesia

A slow clearance of mucus
Chronic respiratory tract infection
Rhinitis
Otitis media
Infertility

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Stereocilum

enormous microvilli (10-50 um)

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Location of stereocilia

auditory sensory cells in organ or Corti
Vestibular sensory cells in vestibular organ
head of epididymis

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Changes to respiratory epithelium due to smoking

Callusing: epithelium adapting to stress/friction

Impacts ciliated cells first and mucus accumulates. Cell loss causes increased division and carcinoma

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Function of stratified squamous epithelium

Protection

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The shape of which cell layer is used to name stratified epithelium?

apical surface

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epidermal peg

epidermis thrust into connective tissue

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dermal papilla

connective tissue thrust into epidermis

Transitional epithelium

Provides distensibility
Prevents urine from diffusing back into the body
ONLY in urinary system

Lateral cell junctions

specialized structures which link each cell pair together into functional unit

Types of cell junctions

Tight junction (lateral surface)
Anchoring junction (lateral and basal surface)
Communicating junction (not physical, only signals)

Tight junctions

unique to epithelial cells, web-like strands of transmembrane proteins fuse cells together. Run all the way around cell Forms a barrier preventing diffusion of water-soluble molecules between adjacent cells and lumen Maintains cell polarity

types of anchoring junctions

1. Zonula adherens 2. Desmosome 3 Hemidesmosome (basal)

Anchoring junctions

resist separation by connecting cytoskeletons of cells/ ECM

Zona adherens

Lateral surface a. below the tight junction, surrounds cells like a belt b. Cadherin is transmembrane glycoprotein, Plaque, Actin filiaments

Desmosome

Lateral surface a. binding spots between cells, b. cadherin is transmembrane glycoprotein, plaque, intermediate filaments

Hemidesmosome

Basal surface Resemble half desmosome Anchor epithelial cells to underlying basement membrane (ECM) Integrin is transmembrane glycoprotein, plaque, intermediate filaments

Exocrine Glands

made of secretory cells derived from surface epithelium secrete product onto external or internal epithelial surfaces Generally have ducts Localized effects

Endocrine glands

Hormones in blood stream travel to target organ No ducts Far reaching effects

example of unicellular gland

goblet cells (exocrine but no ducts)

Are glands mostly unicellular or multicellular?

Multicellular

Simple vs compound duct

compound has branches | simple branched have more than one secretory unit but only one duct

Simple tubular

Intestinal gland

Simple branched tubular

gastric gland

simple coiled tubular

sweat gland

simple branched acinar

sebaceous gland

compound tubular

seminiferous tubules in testes

compound acinar

mammary glands

compound tubuloacinar

salivary glands, pancreas

Serous glands

secrete watery product with proteins/ enzymes | Exocrine pancreas, Parotid salivary, sweat gland (foot pad), lacrimal gland

How does cytoplasm stain in Serous vs mucous glands?

Serous glands have darkly staining cytoplasm because their vesicles are rich in protein and rough ER. Mucous glands stain lightly.

Mucous glands

secrete viscous substance rich in mucin (glycoproteins) Lubricant to protect/ trap foreign bodies Found in goblet cells and sublingual salivary gland

Secretion of most salivary glands (not sublingual)

seromucous

Merocrine/ eccrine glands

exocytosis | Pancreas, seat glands (foot pad)

Apocrine glands

pinch off apical cell cytoplasm with cell product | Sweat glands in haired skin

holocrine glands

whole cells | sebaceous glands

Myoepithelial cells

share basal lamina of acinar cells shares contractility of smooth muscles Bound by oxytocin