30 Questions
Which of the following is not one of the four basic tissues of the body?
Epithelium
Where are the modifications of the apical, basal, and lateral surfaces of epithelial cells located?
On the surfaces of the epithelial cells
What type of tissue is epithelium in terms of vascularity?
Avascular
How many types of basic tissues are there in the body?
Four
What is the primary function of epithelial tissue mentioned in the text?
Protective
Where do epithelial cells attach to and communicate with each other?
Via different types of cell-to-cell junctions
What is the focus of the lecture on epithelium?
Various general and specific characteristic features of epithelia
What is the role of adherens junctions?
Linking the cytoplasmic domain of cadherin to actin filaments
What is the characteristic morphology of fascia adherens?
Sheet-like structure found in cardiac muscle
What happens when calcium is removed from adherens junctions?
The junction is disrupted
Where are macula adherens (desmosomes) typically found?
In simple cuboidal or simple columnar epithelium
What is the function of gap junctions?
Allow exchange of ions, regulatory molecules, and small metabolites
What is the composition of hemidesmosomes' intracellular attachment plaque?
Plectin and BP 230 proteins
What do focal adhesions link to extracellular matrix proteins?
Integrins
Where are focal adhesions found?
Linking actin filaments to extracellular matrix proteins
Which transmembrane proteins form gap junctions?
Connexin proteins
Which type of epithelium appears stratified but is actually a simple epithelium?
Pseudostratified epithelium
What is the acellular structure that attaches epithelial cells to underlying connective tissue called?
Basal lamina
Which type of epithelium serves as a barrier and can be keratinized or non-keratinized?
Stratified squamous epithelium
What determines the distinct surface domains of epithelium: apical, lateral, and basal?
Specific membrane proteins
Which type of epithelium accommodates distension and serves as a barrier?
Transitional epithelium
Which type of epithelium is mainly comprised of packed cells with specific shape and arrangement correlating with their function?
Stratified squamous epithelium
Which type of epithelium is classified based on cell arrangement (simple or stratified) and cell shape (squamous, cuboidal, or columnar)?
Simple squamous epithelium
What are the components of the basal lamina?
Laminins, collagens, entactin/nidogen, proteoglycans
Which stain can be used to demonstrate the presence of basal lamina?
Periodic acid-Schiff stain (PAS) and silver salts
What are the two layers of the basal lamina?
Lamina densa and lamina lucida
What is the function of the basal lamina?
Structural attachment, compartmentalization, filtration
Where is the external lamina found?
On the external surface of nonepithelial cells
What is the main structural component of microvilli and what is their function?
Actin microfilaments, increase in free surface area
Which cell structure is responsible for controlling free molecular movement and preventing diffusion of membrane proteins?
Zonula occludens (tight junction)
Study Notes
Basal Lamina and Cell Surface Modifications in Epithelial Cells
- Basal lamina components are synthesized and secreted by epithelial cells
- Basal lamina can be demonstrated with Periodic acid-Schiff stain (PAS) and silver salts
- Basal lamina has two layers: lamina densa and lamina lucida
- Basal lamina functions include structural attachment, compartmentalization, and filtration
- Basal lamina is composed of laminins, collagens (mainly type IV), entactin/nidogen, and proteoglycans
- External lamina is found on the external surface of nonepithelial cells
- Surface specializations of epithelial cells include microvilli, stereocilia, cilia, and lateral and basal cell surface folds and processes
- Microvilli provide enormous increase in free surface area and contain actin microfilaments
- Stereocilia are immotile processes supported by actin filaments and found in the epididymis
- Lateral folds increase the lateral surface of cells and are prominent in cells that transport fluid rapidly
- Junctional complex in cell-to-cell adhesion includes zonula occludens, zonula adherens, macula adherens, and gap junctions
- Zonula occludens (tight junction) controls free molecular movement and prevents diffusion of membrane proteins
Test your knowledge of epithelial cell structures with this quiz on basal lamina components, surface modifications, and junctional complexes. Learn about the composition and functions of the basal lamina, as well as the various surface specializations of epithelial cells, including microvilli, stereocilia, cilia, and lateral and basal cell surface folds and processes.
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