KINS 1223 Exam 2: Histology (Epithelial Tissue)

2 Classifications of epithelial tissue

1. Covering and lining epithelium

2. Glandular Epithelium

Functions of Covering & Lining Epithelium (5)

1. PROTECTION

2. absorption

3. filtration

4. excretion

5. surface transport

Main function of covering & lining epithelium

protection

Special Characteristics of ET that make them different from other tissues (6)

1. Cellularity

2. Specialized Contacts

3. Polarity

4. Avascularity

5. Regeneration

6. Basment Membrane

Cellularity

(special characteristic)

-nearly all cells

-little to no extra-cellular matrix

Specialized Contacts

(special characteristic)

-all sides of the cell are touching each other except polar surface

-bound by lateral contacts

-cells fit close tg

-tight junctions

-desmosomes

What are epithelial cells bound together by?

Lateral Contacts

Desmosomes

less space

Tight Junctions

more space

What to tight junctions and desmosomes do?

hold cells together

Polarity (special characteristic)

-one free surface

-often covered in microvilli or cillia

Avascularity (special characteristic)

-no blood vessels

Regeneration (special characteristic)

-ET often damaged

-highly mitotic

-mitosis produces new cells to fill in gaps

Basement Membrane (special characteristic)

-ET cells lie on basement membrane

-2 layers: basal lamina and reticular lamina

2 Layers of basement membrane

basal lamina and reticular lamina

How are epithelial tissues classified?

1.) shape of cells

2.) number of layers

3 different cell shapes

squamous, cuboidal, columnar

3 different "layers"/"classes"

simple, pseudostratified, stratified

simple epithelium

-single layer of cells

-all touch basement membrane

-materials pass through easily

pseudostratified epithelium

-"2 fake" layers of cells

-all cells touch basement membrane even though it doesn't look like it

stratified epithelium

-multiple layers of cells

-not all touch the basement membrane

What "layers" of epithelium have all cells touch the basement membrane

-simple

-pseudostratified

What layer do materials pass through easily?

simple epithelium

Functions of simple epithelium (4)

-filtration

-secretion

-diffusion

-absorption

Types of simple epithelium (4)

1. Simple squamous

2. Simple Cuboidal

3. Simple Columnar

4. Pseudostratified Columnar

Why does pseudostratified epithelium look stratified?

-cells aren't all the same height

-nuclei are at different levels

Simple Squamous Epithelium

-single layer of flat cells

-allow diffusion of materials

-secrets serous fluid

Simple Cuboidal Epithelium

-single layer of cube shaped cells

-secretion and absorption, muscous production

-found in liver, mammary, thyroid, salivary glands

Functions of simple squamous epithelium

-helps materials diffuse

-secrets serous fluid

Functions of simple cuboidal epithelium

-secretion and absorption

-mucous production

Where are simple cuboidal cells found?

liver, mammary, thyroid, salivary gland

Simple columnar epithelium

-single layer of tall narrow cells

-secretion and absorption

-produces muscous

-found in lining of GI tract, uterine tubes, kidney, uterus

Similarity between simple cuboidal and simple columnar

both produce mucous

Functions of simple columnar epithelium

-secretion and absorption

-produce mucous

Where are simple columnar cells found?

lining of GI tract, uterine tubes, uterus, kidneys

Pseudostratified columnar epithelium

-single layer of cells differing heights (some don't reach the free surface)

-secretes and propels respiratory mucous

Function of pseudostratified columnar epithelium

secret and propel respiratory mucous

Main Function of stratified epithelium

protection

Why is protection the main function of stratified epithelium?

its thicker and stronger

4 types of stratified epithelium

stratified squamous

stratified cuboidal

stratified columnar

transitional

(T/F) Transitional epithelium is a simple epithelium

F: its stratified

Transitional Epithelium

-specialized to withstand changes in tension

-layers of cuboidal and columnar

How are stratified epithelia named?

shape of surface cells

2 Variations of Stratified Epithelium

Keratinized

Nonkeratinized

Keratinized

-has layer surface of dead cells

-palms of hands and feet

Nonkeratinized

-lacks surface layer of dead cells

-waterproof surface

most widespread epithelium in the body

stratified squamous

Nonkeratinized stratified squamous Epithelium

multiple layers of flat cells that don't have a surface layer of dead cells

-found in vagina, tongue, esophagus

Where are nonkeratinzed stratified squamous located?

vagina, tongue, esophagus

stratified cuboidal epithelium

2 or more layers of cube shaped cells

secrete sweat, sperm and hormones

Transitional Epithelium

-change from round to flat when stretched

-allow for filling of urinary tract

-found in ureter and bladder

What do stratified cuboidal epithelium produce?

-secrete sweat, sperm and hormones

glandular epithelium

produce and secrete substances

2 Classifications of Glandular Epithelial

endocrine, exocrine

Endocrine Glands

ductless

secretes hormones into extracellular fluid

Exocrine Glands

-secret products into ducts

-i.e: liver, mammary, sweat

Main difference between endocrine and exocrine glands

Endo: secrete fluid into extracellular liquid

Exo: secrete fluid into ducts

T/F: Endocrine glands do not have ducts

true

Product of glandular Epithelium

hormones

2 Structures of Exocrine glands

-unicellular

-multicellular

Unicellular Exocrine Glands

-single epithelial cell

-goblet cell

Goblet cell

unicellular exocrine gland cell

Multicellular Exocrine Glands

-have a epithelium derived duct

-secretory gland cells

2 types of multicellular exocrine glands

simple and compund

Simple Multicellular Exocrine Glands

unbranched ducts

Compound Multicellular Exocrine Glands

branched ducts

4 Body Membranes

1 Synovial

3 Epithelial

3 epithelial membranes

serous, mucous, cutaneous

Serous Membrane

-moist

-lines cavities not open to the outside

-peritoneum (lines abdominal cavity)

-2 layers: parietal and visceral

ex of serous membrane

peritoneum- lines abdominal cavity

2 layers of serous membranes

parietal and visceral

Parietal serous membrane

lines cavity

Visceral Serous Membrane

covers/reflects over the organ

Mucous Membrane

-lines cavities open to the outside

-digestive and respiratory tract

-made of simple and stratified epithelium

-made of loose ct: lamina propina

T/F: mucus membranes line body cavities open to the outside

true

lamina propina

loose ct within mucous membrane

Cutaneous membrane

skin

Primary and largest organ

skin