epithelium Flashcards
What is the definition of epithelium?
A tissue that lines the surfaces and cavities of the body.
What are the main functions of epithelium?
Protection, absorption, secretion, and sensation.
What are the two main types of epithelium?
Covering (lining) epithelium and glandular epithelium.
What is simple epithelium?
Epithelium with a single layer of cells.
What is stratified epithelium?
Epithelium with multiple layers of cells.
What are the subtypes of simple epithelium?
Simple squamous, cuboidal, columnar, and pseudostratified.
What is the function of simple squamous epithelium?
Facilitates diffusion and filtration; found in alveoli and blood vessels.
Where is simple cuboidal epithelium found?
In kidney tubules, small ducts, and glands.
What is the function of simple columnar epithelium?
reabsorption and secretion
What is pseudostratified epithelium?
A single layer of cells appearing stratified, found in the respiratory tract.
What is keratinized stratified squamous epithelium?
Epithelium with a dead layer of keratinized cells, found in skin.
Where is non-keratinized stratified squamous epithelium found?
In the esophagus, mouth, and vagina.
what and where is transitional epithelium?
Epithelium that stretches, found in the bladder and urinary tract.
What is the basement membrane?
A thin layer supporting epithelium, separating it from connective tissue.
What is the role of tight junctions in epithelium?
Prevent leakage of substances between cells.
What are cilia and where are they found?
Hair-like structures aiding movement, found in the respiratory tract.
What is microvilli’s function?
Increase surface area for absorption; found in the intestines.
What is the difference between cilia and microvilli?
Cilia are motile; microvilli are non-motile and increase surface area.
What is epithelium composed of?
Closely packed cells with little or no extracellular matrix.
What are the characteristics of epithelial tissues?
Avascular (lack blood supply)
Supported by basement membrane
Polarized (apical and basal surfaces)
High regenerative capacity
What is the basement membrane and its layers?
It is a thin supporting layer between epithelium and connective tissue. Layers include:
Basal lamina (produced by epithelium)
Reticular lamina (produced by connective tissue)
What is the function of the basement membrane?
Provides structural support, acts as a barrier, and regulates exchange between epithelium and connective tissue.
Where is simple squamous epithelium located?
alveoli of lungs, lining of blood vessels (endothelium), and lining of body cavities (mesothelium)
What are the characteristics of simple cuboidal epithelium?
Single layer of cube-shaped cells with centrally located nuclei.
What is the main function of simple cuboidal epithelium?
Secretion and absorption.
What are the features of simple columnar epithelium?
Single layer of tall, column-like cells with nuclei near the base.
What is the function of simple columnar epithelium?
Absorption and secretion of mucus or enzymes.
Where is pseudostratified columnar epithelium found?
Upper respiratory tract (trachea and bronchi).
What is the function of pseudostratified columnar epithelium?
Secretion and movement of mucus via cilia.
What is stratified squamous epithelium?
Multiple layers of flat cells at the surface with basal cuboidal or columnar cells.
What are the two types of stratified squamous epithelium?
Keratinized: Found in skin (dead layer of keratin).
Non-keratinized: Found in mouth, esophagus, and vagina.
Where is transitional epithelium found?
Where is transitional epithelium found?
What are microvilli, and where are they located?
Finger-like projections that increase the surface area for absorption. Found in the small intestine.
What are cilia, and what is their function?
Motile hair-like structures that move particles across the surface of cells, e.g., in the respiratory tract.
What is simple squamous epithelium?
It is a single layer of flat, thin cells with a centrally located, flattened nucleus.
What is the function of simple squamous epithelium?
provides a thin and smooth surface
Where is simple squamous epithelium found?
Alveoli of the lungs (gas exchange).
Glomeruli - bowman’s capsule of kidneys (filtration).
vessels lining (endothelium)
Body cavities lining (mesothelium).
what or where is serous sacs of simple squamous epithelium
pluera , pericardium , peritonium ( mesothelium)
Why is simple squamous epithelium suited for diffusion?
Because the cells are thin and flat, allowing molecules to pass through easily.
What is mesothelium?
It is the simple squamous epithelium that lines body cavities such as the pleura (lungs), pericardium (heart), and peritoneum (abdomen).
What is simple cuboidal epithelium?
A single layer of cube-shaped cells with a centrally located, round nucleus.
What is the function of simple cuboidal epithelium?
Secretion and reabsorption.
Where is simple cuboidal epithelium found?
Kidney tubules (reabsorption).
Small ducts of glands (salivary, pancreas).
Thyroid follicles.
Ovaries (germinal epithelium
What does simple cuboidal epithelium look like under a microscope?
Appears as a layer of cube-like cells with round, centrally located nuclei.
What is simple columnar epithelium?
A single layer of tall, column-shaped cells with oval nuclei near the base.
What is the difference between ciliated and non-ciliated simple columnar epithelium?
Ciliated: Has cilia for movement ( fallopian tube , uterus , lung bronchioles )
non-ciliated: Specialized for absorption (e.g., in the intestines and stomach )
What is pseudostratified columnar epithelium?
It is a single layer of cells that appears stratified because the nuclei are located at different levels.
Why does pseudostratified columnar epithelium appear stratified?
Because the nuclei of the cells are located at varying heights, giving a false appearance of multiple layers.
What are the two types of pseudostratified columnar epithelium?
non-ciliated , ciliated with non-motile cilia - ciliated with motile cilia and goblet cell
Where is ciliated pseudostratified columnar epithelium found?
In the respiratory tract, such as the trachea and bronchi.
Where is non-ciliated pseudostratified columnar epithelium found?
In parts of the male reproductive tract such as the epididymis.
What is the role of goblet cells in pseudostratified columnar epithelium?
Goblet cells secrete mucus that traps dust, bacteria, and other particles.
What type of epithelium lines the epididymis?
Non-ciliated pseudostratified columnar epithelium.
where we can find non-ciliated pseudostratified epithelium
vas defferens
What is stratified squamous epithelium?
It consists of multiple layers of cells, with flat squamous cells at the surface and cuboidal or columnar cells at the basal layer.
What are the two types of stratified squamous epithelium?
Keratinized and Non-keratinized.
Where is keratinized stratified squamous epithelium found?
On the skin surface (epidermis).
What is the function of keratinized stratified squamous epithelium?
Provides protection against mechanical stress, water loss, and pathogens due to the presence of keratin.
Where is non-keratinized stratified squamous epithelium found?
Mouth (oral cavity )
Esophagus
vagina
cornea
What is the basal layer of stratified squamous epithelium composed of?
Cuboidal or columnar cells actively dividing to replace surface cells.
what is the inter-mediated layer composed of ?
multiple layers of polyhedral cells
What is transitional epithelium?
A specialized epithelium with multiple layers of cells that can change shape.
( non-clear and non-wavy basement membrane )
Where is transitional epithelium found?
Urinary bladder
what is superficial layer of transitional epithelium
dome-shaped
What is the function of transitional epithelium?
llows organs like the bladder to stretch and recoil while maintaining a protective lining
*protection and distensibility
what is stratified cubical epithelium
2-3 layers of cubical cells
where is stratified cubical epithelium?
ducts of sweat gland
what is stratified columnar epithelium?
the super facial layer is formed of columnar cells
where is stratified columnar epithelium?
non-ciliated = in large ducts of glands
ciliated = in fetal esophagus
