Histo Lecture 2 Epithelial Tissue

Front 1

What are four types of tissue?

Back 1

epithelial
muscle
nervous
connective

Front 2

How does epithelial tissue get its nutrients?

Back 2

via diffusion from blood vessels in nearby connective tissue. blood vessels do not penetrate epithelium.

Front 3

What germ layer is epithelial tissue derived from?

Back 3

All three germ layers:
ectoderm: epidermis
endoderm: lining of GI, respiratory tract
mesoderm: endothelium, mesothelium

Front 4

Where is endothelium found?

Back 4

lines blood vessels

Front 5

Where is mesothelium found?

Back 5

lines cavities (pericardial, peritoneal cavity), serous tissues

Front 6

Types of epithelial tissue

Back 6

1) Membraneous epithelia - sheet-like tissues that cover or line surfaces, cavities, etc..

2) Glandular epithelia - perform secretory function

Front 7

Functions of epithelial tissue

Back 7

1) Protection and containment (skin)
2) Absorption (Intestine)
3) Secretion (Glands)
4) Sensation (Neuroepithelium)
5) Contractility (Myoepithelium)

Front 8

Characteristics of Epithelial Tissue

Back 8

1) Cells closely bound to one another by membrane specializations (cell junctions); form continuous sheets
2) Supported by basement membrane (separates them from underlying supporting tissue)
3) Not penetrated by blood vessels
4) Epithelial cells are polar

Front 9

What kind of collagen is in the basement membrane?

Back 9

Type IV Collagen -- unique to the basement membrane!

Front 10

How are epithelial tissue classified?

Back 10

1) Number of cell layers
One layer thick
More than one layer
2) Morphology
Flat (squamous)
Columnar
Cuboidal
3) Specializations
Cilia
Stereocilia
Microvilli
Keratin

Front 11

Simple epithelia

Back 11

Single layer of cells(squamous, cuboidal or columnar) located on a surface or facing a lumen in places where diffusion, adsorption of secretion occur; contain cilia or microvilli, do not have keratin

Front 12

Simple squamous epithelium

Back 12

Shape - Flat cells, scales
Function - diffusion of fluids or gases
Location - lungs, blood, lymphatic vessels and more

Front 13

Simple cuboidal epithelium

Back 13

Shape - cells as tall as they are wide, round central nucleus
Function - excretion, secretion, absorption
Location - ducts of kidney, thyroid, salivary glands

Front 14

Simple columnar epithelium

Back 14

Shape - Cells taller than cuboidal cells, elliptical nucleus located basally
Function - Absorption
Location - Intestines

Front 15

Simple columnar ciliated epithelium

Back 15

Shape - columnar cells with cilia at apical surface
Function - propel ovum over cells surface toward uterus
Location - female reproductive tract

Front 16

Pseudostratified columnar ciliated epithelium

Back 16

Shape - ciliated columnar cells with nuclei at different positions
Function - propel mucus and entrapped particles
Location - trachea

Front 17

Stratified epithelium

Back 17

Two or more layers of cells
Protective function
Classification: based on shape and function of the surface cells

Front 18

Stratified squamous epithelium

Back 18

Shape - many layers, surface layers, squamous
Function - withstand chronic abrasion
Location - oral cavity, esophagus, cervix, vagina

Basal layer has more cuboidal shapes, can be undergoing mitosis
As cells differentiate/move towards surface, they becomes more squamous/flat in shape

Front 19

Why is the basement membrane of the esophagus irregular instead of flat?

Back 19

Gives it structure, strength (called epidermal pegs); also contains blood vessels than supply the epithelium

Front 20

Stratified squamous keratinized epithelium

Back 20

Shape - many layers, squamous, surface layer of keratin
Function - withstand chronic abrasion
Location - epithelial surface of skin

Front 21

Stratified cuboidal epithelium

Back 21

Shape: 1-2 layers of cuboidal cells
Function - provide thicker lining
Location - larger excretory ducts of exocrine glands, e.g. salivary glands

Front 22

Transitional epithelium

Back 22

Shape - many layers of cells, surface layer large, round pillow shape - can be binucleated at lumenal site; cells frequently bulge into lumen.
Function - withstand toxicity of urine, accommodate stretch (i.e. after drinking a lot of water)
Location - urinary tract (bladder etc.)

Front 23

Glandular epithelia

Back 23

Invagination of epithelial surfaces
Formed during embryonic development
Proliferation of epithelia into underlying tissue

Front 24

Types of Exocrine Glands

Back 24

Simple tubular
Simple coiled tubular
Simple branched tubular
Simple acinar
SImple branched acinar
Compound branched tubular
Compound acinar
Compound tubulo-acinar

Front 25

Modes of exocrine secretion

Back 25

1) Merocrine - most common, no loss of plasma membrane (globlet cell aka unicellular gland)
2) Apocrine - vesicles (some membrane cells)
3) Holocrine - whole cell broken to release its secretory products

Front 26

Serous vs Mucous Glands

Back 26

Serous: Nuclei rounder, displaced somewhat towards basal surface, secreted product retained within apical cytoplasm, sometimes recognized as mucigen granules or secretory droplets, cytoplasm acidophilic

Mucous: Foamy appearance of cytoplasm (since secretion is washed out by EtOH-- cyto puffier) with Nuclei flattened against basement membrane by secreted product

Front 27

how do you know if a squamous cell is alive/non-cornified?

Back 27

presence of the nucleus. In stratified squamous epithelium, the presence of a nucleus in the outermost layer indicates a living cell, and not a cell undergoing cornification (keratinizing)

Front 28

how to differentiate between cells with cilia versus cells with microvilli?

Back 28

presence of basal bodies (dark spots) at apical surface of ciliated cells

Front 29

where is pseudostratified columnar epithelia with stereocilia found?

Back 29

exclusively in male reproductive tract

Front 30

stratified columnar epithelium

Back 30

unusual type, lines ducts of salivary gland

Front 31

terminal bar

Back 31

dark dot-like structure immediately below the apical cell surface.

Front 32

spinous layer

Back 32

The stratum spinosum (or spinous layer) is a layer of the epidermis found between the stratum granulosum and stratum basale. This layer is also referred to as the "spinous" or "prickle-cell" layer. This apearence is due to desmosomal connections of adjacent cells. The cells in the stratum spinosum produce and secrete bipolar lipids which prevent evaporation, helping to "water-proof" the skin. Keratinization begins in the stratum spinosum.