Epithelium Week 2 Flashcards
What are the 4 basic tissues in the body?
Epithelium, Muscle, Nerve, Connective Tissue
What are epithelia ?
Sheets of cells that cover or line internal and external body surfaces
Form secretory glands and ducts
What are the functions of epithelia?
- Protection
- Absorption (intestinal lining)
3.Secretion (salivary gland)
Cells are ________ packed together in epithelia with one free surface that faces the __________.
Tight, lumen of the organ (internal cavity)
_____________ attaches the epidermis to the ___________ .
Connective tissue , basement membrane
What is the basement membrane and what is its function?
An acellular meshwork of carbohydrates and proteins that serve as a filter and membrane.
What is the name of the connective tissue that attaches the epithelium to the basement membrane? What additional function does it have?
Lamina propria; Since the epithelium is avascular, the lamina propria provides nutrition and O2 via vessels
Is the epithelia vascular or avascular ?
Avascular
What cells are in a single layer and are flat?
Simple Squamous
Describe the cytoplasm and nucleus of simple squamous epithelial cells
Scanty (thin) cytoplasm and flat nuclei
Simple squamous cells are specialized for ___________
Simple diffusion across cytoplasm
Where are simple squamous cells located?
Air sacs of lungs, lining of blood vessels, structures in kidney
Describe the structure of simple cuboidal cells. How do they appear in a histological section?
Equal physical dimensions. They appear as squares in histological sections in one layer.
Nuclei appear ________ in simple cuboidal cells
Round
What are the functions of simple cuboidal cells?
Protection
Absorption
Secretion of substances needed for the organs they line
Where are simple cuboidal cells found?
Collecting tubules of kidney participate in reabsorption of water and filter
What cells are taller than they are wide and in one layer?
Simple Columnar Epithelium
Nuclei appear __________ in simple columnar epithelium.
Round; nuclei are pushed to the area AWAY from the lumen to create space for cell activities such as secretion.
What are the functions of simple columnar epithelium?
- Protection
- Absorption and secretion
- Transport of materials
Where can simple columnar epithelial cell be found?
Bronchial tubes of lungs, uterine tubes, lining of stomach and intestinal tract
How are stratified epithelia classified?
By the TOP layer of cells.
Which layer of stratified epithelia can touch the basement membrane?
Only the last layer
How are nuclei arranged in stratified epithelia?
They are aligned with each other
The rarer kinds of stratified epithelia are _____________. They are found in _________.
Stratified columnar and cuboidal , large glands and the male urethra
Where are stratified cuboidal epithelium found ?
Sweat glands, cells recycle sodium and chloride ions in sweat
Where are stratified columnar epithelia found?
Male urethra to protect tissue from urine by secreting mucus
What is the most common stratified cell?
Stratified squamous
Describe what stratified squamous cells look like. What do the nuclei look like?
Piles of flat cells with many layers, lines of nuclei are hard to see.
Where are stratified squamous cells located?
Anywhere there is friction; vocal cords, esophagus, epidermis, vagina
What adaptation allows for stratified squamous cells to sustain friction. Describe it.
Keratinization, Cells synthesize keratin filaments that enhance cell toughness.
How do keratinized cells appear compared to non keratinized cells?
Keratinized cells may eject organelles including nuclei so cells close to the lumen will lack nuclei
In keratinized cells, cells _______ from the lumen will lack nuclei.
close
Epithelium has a ________ turnover rate.
high
What are pseudo stratified epithelium? Which cells touch the basement membrane?
Epithelia of different shapes and sizes that ALL touch the basement membrane?
What is urothelium?
Urothelium is transitional epithelium that is found in the bladder and the ureter.
What is the function of the urothelium?
To maintain the urinary barrier even when the bladder is full.
Describe the two distinct appearances of transitional epithelium ?
There is a compact version and a taller version when the bladder is empty. Both versions have unique rounded cells.
What are umbrella cells?
Umbrella cells are a key feature of transitional epithelium that are rounded whose dense plaques help maintain barrier function
Can umbrella cells be multinucleated?
Yes
Epithelial cells are _____. This means that there is an ________ distribution of proteins and organelles in the cytoplasm.
polar, uneven
Describe the polarity of epithelial cells.
There are 3 domains.
- Apical
- Basal
- Lateral
Describe the Apical domain of the cell
Cell surface that faces the lumen
Describe the Basal domain of the cell
Cell surface that attaches to the basement membrane in simple epithelium