epithelial tissue

What is the purpose of epithelial tissue.

Covers and forms boundaries

What are the 2 main types of epithelial tissue ( by location)

Covering and lining epithelial

Glandular epithelial

What are the characteristics of epithelial tissue

Polarity

Specialized contacts

Supported by connective tissue

Avascular but innervated

Can regenerate

What are the functions of epithelial tissue

Protection

Absorption

Filtration

Excretion

Secretion

Sensory reception

Do epithelial cells have polarity

Yes

Describe the apical surface

Upper free, exposed to exterior

Smooth/slick

Most have microvilli to increase surface area

Some have cilia

Describe the basal surface

Lower and attached

Non cellular basal lamina

Glycoprotein and collagen fibers adjacent

Adhesive sheet

Selective filter

Scaffolding for cell migration in wound repair

What are specialized contacts of epithelial tissue

They bind adjacent cells together and form continuous sheets

Tight junctions aka impermeable junctions

Desmosomes aka anchoring junctions

what is epithelial tissue supported by

Connective tissue

where is the reticular lamina and what fibers does it have

Deep to basal lamina

Has network of collagen fibers

What is the basement membrane composed of

Basal lamina + reticular lamina

What does the basement membrane do

reinforces epithelial sheet

Defines epithelial boundary

Resists stretching and tearing

Does epithelial tissue have blood vessels

No! Avascular

How is epithelial tissue nourished

By diffusion from underlying connective tissue

Is epithelial tissue supplied by nerve fibers

Yes

What type of regeneration capacity does epithelial tissue have

High regeneration capacity

What is regeneration simulated by in epithelial tissue

The loss of apical-basal polarity and lateral contacts

Ex: friction or hostile substances

How do you replace lost cells in epithelial tissue

By cell division

What is glandular epithelial classified by

Exocrine or endocrine

Number of cells forming the gland ( unicellular/ multicellular )

Do endocrine glands have ducts?

No they are ductless

What do endocrine glands do?

Secrete hormones through lymph or blood to specific target organs

Do exocrine glands have ducts?

Yes

Name examples of exocrine glands

Mucus

Sweat

Oil

Salivary

Examples of unicellular exocrine glands

Mucus or goblet cells

Where are unicellular exocrine glands found

In epithelial linings

Intestinal & respiratory tract

Do all unicellular exocrine glands produce mucin

Yes

How to classify multicellular exocrine glands

By structure ( unbranched / branched)

And type of secretion ( merocrine, holocrine, apocrine )

What type of multicellular exocrine glands produce is this

Simple tubular

What type of multicellular exocrine glands produce is this

Simple branched tubular

What type of multicellular exocrine glands produce is this

Compound tubular

What type of multicellular exocrine glands produce is this

Simple alveolar

What type of multicellular exocrine glands produce is this

Simple branched alveolar

What type of multicellular exocrine glands produce is this

Compound alveolar

What is the most common type of secretion in multicellular exocrine glands

Merocrine glands

Where are Merocrine glands located

Sweat/Salivary glands, pancreas

What is the function of merocrine glands

Secrete produce by exocytosis

Where are Holocrine glands located

Sebaceous (oil) glands

What is the function of holocrine glands

Secretions accumulate and cell ruptures releasing secretions and dead cell fragments