What is the significance of the basement membrane?
It provides structural support, acts as a barrier and filter, and regulates cell behavior.
Name the components of the basement membrane.
Type IV collagen, Laminin, Nidogen, Perlecan, and Type III collagen.
What are tight junctions, and where are they found?
Tight junctions form a seal between adjacent cells and are found at the apical region of epithelial cells.
What is the function of adherent or anchoring junctions?
These junctions provide strong cell adhesion, located just below tight junctions.
Describe desmosomes and their role.
Desmosomes are disc-shaped structures that act as spot-welds, providing mechanical stability.
What are gap junctions and their function?
Gap junctions are channels that allow communication between adjacent cells.
What is the role of microvilli in epithelial cells?
Microvilli increase the surface area for absorption, especially in the small intestine.
Where are stereocilia found, and what is their function?
Stereocilia are found in the male reproductive system for absorption and in the inner ear for sensory detection.
What is the function of cilia in epithelial tissues?
Cilia are motile structures that propel substances across the epithelial surface, such as mucus in the respiratory tract.
What is simple squamous epithelium, and where is it located?
Simple squamous epithelium is composed of flat cells, found in the alveoli of lungs and the lining of blood vessels.
What is the role of simple cuboidal epithelium?
Simple cuboidal epithelium is involved in secretion and absorption, found in glands and kidney tubules.
Where can you find simple columnar epithelium, and what is its function?
Simple columnar epithelium is found in the lining of the digestive tract, where it absorbs nutrients and secretes mucus.
Describe pseudostratified epithelium and its location.
Pseudostratified epithelium appears stratified but is a single layer with nuclei at different levels, usually found in the respiratory tract.
What is the function of stratified squamous epithelium?
Stratified squamous epithelium provides protection, found in the skin (keratinized) and moist surfaces like the mouth and esophagus (non-keratinized).
Where is stratified cuboidal epithelium found, and what is its role?
Stratified cuboidal epithelium is found in the ducts of sweat glands and other large glands, providing protection.
What is transitional epithelium, and where is it located?
Transitional epithelium is a specialized type of stratified epithelium that can stretch, found in the urinary bladder and ureters.
Explain the process of transcellular transport in epithelial cells.
Transcellular transport involves the movement of substances directly through epithelial cells via active or passive transport.
What is paracellular transport, and how is it regulated?
Paracellular transport involves the movement of substances between epithelial cells, regulated by tight junctions.
What role do epithelial cells play in ion transport?
Epithelial cells maintain electrolyte balance, crucial in areas like the kidneys.
What are the key functions of epithelial tissues?
Protection, absorption and secretion, filtration, and sensory reception.
How does the epithelial layer regenerate after damage?
The basement membrane acts as a scaffold for repair and regeneration.
Where are stem cells located in epithelial tissues?
Stem cells are located in the basal layer or specific niches within the epithelium.
What is the basal lamina, and why is it important?
The basal lamina is part of the basement membrane, providing structural support and anchoring epithelial cells to underlying connective tissue.
What is the significance of epithelial cell polarity?
Epithelial cells are polarized to perform their functions effectively, with distinct basal, apical, and lateral surfaces.
How do microvilli contribute to absorption in epithelial cells?
Microvilli increase the surface area of epithelial cells, enhancing their ability to absorb nutrients.
What is the function of the lamina propria in the digestive system?
The lamina propria is connective tissue that provides nutrients and oxygen to the epithelial lining of the digestive, respiratory, and urinary systems.
What are papillae in the context of epithelial tissues?
Papillae are small evaginations between the area of contact of two tissues, increasing surface area and strength of adhesion.
Describe the structure and function of the basal pole in epithelial cells.
The basal pole is the region of the epithelial cell that contacts the extracellular matrix and connective tissue, anchoring the cell in place.
What is the apical pole of an epithelial cell?
The apical pole is the part of the epithelial cell facing the tissue space, often involved in absorption and secretion.
How do actin filaments contribute to the function of epithelial cells?
Actin filaments in epithelial cells are involved in cell shape, structure, and movement, especially in areas like the terminal web of the apical pole.
What is the terminal web in epithelial cells?
The terminal web is a cytoskeletal feature at the apical pole of epithelial cells, composed of actin filaments linked to adherent junctions.
What role does Type IV collagen play in the basement membrane?
Type IV collagen forms a mesh-like network providing structural strength and support to the basement membrane.
How does laminin contribute to the basement membrane?
Laminin is a glycoprotein that binds to transmembrane proteins like integrins, playing a role in cell differentiation, adhesion, and migration.
What is the role of nidogen in the basement membrane?
Nidogen connects laminin and Type IV collagen networks, stabilizing the overall structure of the basement membrane.
What is perlecan, and how does it function in the basement membrane?
Perlecan is a proteoglycan that contributes to the filtration properties of the basement membrane and binds to other components like laminin and collagen.
What is the difference between basal lamina and reticular lamina?
The basal lamina is composed of Type IV collagen and laminin, while the reticular lamina is made up of Type III collagen, connected to the basal lamina by Type VII collagen.
How does the basement membrane support tissue integrity?
The basement membrane provides structural support, acts as a barrier, and regulates cell behavior, ensuring the integrity and function of the tissue.
What are the main differences between simple and stratified epithelia?
Simple epithelia consist of a single cell layer, while stratified epithelia have multiple cell layers, with only the deepest layer in contact with the basement membrane.
What is the function of keratinized stratified squamous epithelium?
Keratinized stratified squamous epithelium provides protection against mechanical stress and dehydration, found in the skin.
Where is non-keratinized stratified squamous epithelium found, and what is its function?
Non-keratinized stratified squamous epithelium lines moist surfaces like the mouth and esophagus, providing protection without the keratin layer.
What is the role of transitional epithelium in the urinary system?
Transitional epithelium allows for stretching and recoiling, accommodating the changing volumes in the urinary bladder and ureters.
How do epithelial cells contribute to sensory reception?
Epithelial cells in sensory organs detect changes in the environment, such as taste buds or the olfactory epithelium.
What is the significance of the extracellular matrix in epithelial tissues?
The extracellular matrix provides support, segregates tissues, and regulates intercellular communication.