Epithelium Flashcards
What are the four basic types of tissues in the human body?
Epithelial, connective, nervous, and muscle tissues.
What is epithelial tissue, and where is it found?
Epithelial tissue consists of closely packed cells forming layers that cover body surfaces, line cavities, and form glands.
How is epithelial tissue classified by the number of cell layers?
Simple epithelium (one layer), stratified epithelium (multiple layers), and pseudostratified epithelium (appears layered but is single).
What are the shapes of epithelial cells, and where might you find each type?
Squamous: flat, found in lungs.
Cuboidal: cube-shaped, found in kidney tubules.
Columnar: tall, found in the intestines.
Describe the function and location of simple squamous epithelium.
It allows diffusion and filtration, found in alveoli and blood vessels.
What is the main function of simple cuboidal epithelium, and where is it located?
Its main functions are secretion and absorption, located in glands and kidney tubules.
How does simple columnar epithelium appear under a microscope, and what are its functions?
Appears as a single layer of tall cells with nuclei near the base, functions in absorption and secretion, found in the intestines.
What are pseudostratified epithelia, and where are they commonly found?
They appear multi-layered but are single-layered; found in the respiratory tract.
Differentiate between keratinized and non-keratinized stratified squamous epithelium.
Keratinized: found in the skin, provides protection and water resistance.
Non-keratinized: found in moist areas like the mouth and esophagus, protects against abrasion.
Where is stratified cuboidal epithelium typically found, and what is its main function?
Found in ducts of sweat glands and salivary glands, its main function is protection and some excretion.
What is the function of transitional epithelium, and where is it located?
Allows for stretching, found in the urinary bladder.
Name and describe three surface specializations found in epithelial cells.
Microvilli: increase surface area for absorption, found in intestines.
Cilia: move substances across cell surfaces, found in respiratory tract.
Stereocilia: longer, for absorption, found in epididymis.
What are tight junctions, and what role do they play in epithelial cells?
They seal adjacent cells to prevent leakage, found near the apical surface of cells.
What are gap junctions, and why are they important?
They allow the transfer of ions and small molecules between cells, enabling communication.
How do desmosomes support epithelial tissue?
They provide strong adhesion between cells, helping the tissue withstand mechanical stress.
Explain the function of hemidesmosomes in epithelial cells.
Hemidesmosomes anchor epithelial cells to the basement membrane, providing stability.
What is the basement membrane, and why is it essential?
A thin layer supporting epithelial cells, anchoring them and regulating molecule movement.
Describe the structure and function of ciliated columnar epithelium.
Single layer of columnar cells with cilia, found in the uterine tube, moves mucus or particles.
Which epithelial tissue types are most protective, and where are they found?
Stratified squamous (skin, esophagus) and transitional epithelium (urinary tract) are most protective.
What are some diseases associated with epithelial cell junctions?
Diseases include psoriasis (skin inflammation) and Darier disease (impaired desmosomes).
What are the main types of epithelial tissue?
The main types are simple (single cell layer) and stratified (multiple cell layers) epithelium, each further classified by cell shape as squamous, cuboidal, or columnar.
How is epithelial tissue classified by function?
Epithelial tissue is classified as surface epithelium (covering/lining surfaces and cavities) and glandular epithelium (specialized for secretion, found in glands like the thyroid and sebaceous glands).
How does the type of epithelium relate to its function?
Simple squamous: diffusion/filtration (e.g., alveoli).
Simple cuboidal: secretion/absorption (e.g., kidney tubules).
Simple columnar: absorption/secretion (e.g., intestines).
Stratified squamous: protection (e.g., skin).
Transitional: allows stretching (e.g., bladder).
What are the main epithelial surface specializations, and their functions?
Cilia: movement of substances across the surface (e.g., respiratory tract).
Microvilli: increase surface area for absorption (e.g., intestines).
Stereocilia: long, immotile, for absorption (e.g., epididymis).
Flagella: movement, seen in sperm cells.
