Chapter 3A

Histology

study of tissues

tight junctions

Form tight seals to prevent passage of substances between cells

Where can you find tight junctions?

stomach, intestines, urinary bladder

adherens junctions

Fasten cells to each other to resist separation

Where can you see adherens junctions

Epithelial surfaces of the GI tract

Desmosomes

Anchoring junctions that prevent cells from being pulled apart

Where is having desmosomes important to have?

Cardiac muscles. It prevents the muscle from pulling apart

Hemidesmosomes

attach epithelial cells to the basement membrane

gap junctions

Formed by tiny fluid filled tunnels that permit passage of chemical/electrical signals between cells

Where are gap junctions found?

Nervous system, heart muscle, GI tract

T/F: epithelial cells are vascular

false, they are avascular (no blood supply)

T/F: connective tissues is vascular

True

innervate

Has a nerve supply

What are the general functions of epithelial tissue

protection, absorption, filtration, secretion, excretion and diffusion

How are surface epithelium classified?

By arrangement, cell shape

How many layers does a simple surface epithelium have?

Single layer

Stratified

more than one layer

Pseudostratified

Single layers that appear stratified

What function are squamous cell shapes good for?

Diffusion and filtration

What function does a cuboidal cell preform?

Absorption and secretion

What function does a columnar cell have?

Absorption and secretion

Transitional cells

Undergo changes to accommodate distensión.

Think bladder or stomach

When do you look for keratinization

If it is stratified squamous

When do you look for cilia

If the cell shape is columnar

intersitial

between cells

glandular epithelium

specialized epithelial cells organized to form glands that secrete substances into ducts, onto a surface, or into the blood

Endocrine

ductless gland that secrete hormones via interstitial fluid

exocrine glands

Glands that secrete substances outward through a duct

How are exocrine glands classified?

Based on how their secretion is released

merocrine glands

Secrete product by way of secretory vesicles

What is an ex of merocrine gland?

Salivary, sudoriferous

apocrine glands

Secretes by pinching off the top portion of the cell which becomes the product

What is an ex of an apocrine gland?

Mammary, sudoriferous

holicrine glands

Mature cell ruptures and dies to become secretory product

Ex of Holicrine gland

Sebaceous