H/E Lecture 11 Flashcards
What stain is specifically used for basement membranes?
Periodic Acid Schiff.
What two layers make up the basement membrane?
Basal Lamina
Reticular Lamina
Components in the basal lamina are synthesized by ___?
Epithelial cell
What are the major functions of the basal lamina?
Attachment of epithelium to CT
Regulation/filtration
Scaffolding for regeneration
Reticular lamina components are synthesized and secreted by___?
Fibroblast cells (CT cells)
What fibers are in the reticular lamina?
type III collagen
What is the purpose of the reticular lamina?
anchor basal lamina to the CT
What anchors the basal lamina to the reticular lamina?
anchoring fibrils and plaques
What are the general functions of epithelium?
Protection (covers and lines)
Secretion
Absorption (intestines)
Transport along a surface (lungs)
What are the three types of epithelium in regard to proliferation?
Permanent: no mitosis
Stable: normally no mitosis but can if needed
Labile: steadily renewable, stem cells present, very regulated
What is neoplasia?
Uncontrolled proliferation of cells.
What are the differences between benign and malignant tumors?
Benign: slow, no metastasis, called adenoma or papilloma
Malignant: fast, metastasis, carcinoma or adenocarcinoma
Describe adherens junctions.
belt like or “zonula”
CAMs are E-cadherin
Linked to actin filaments inside the cell
Towards the apical side of the cells
Resists mechanical separation of the cells
Describe desmosomes.
spot welds or “macula” adherens
CAMs are desmosomal cadherins, overlap to form cadherin zipper between cells
Keratin filaments (intermediate filaments) attach to the attachment plaque
All below the adherens junction belt
Very strong, resist tearing and shearing forces
Describe hemidesmosomes.
bind epithelial cells to the basal lamina
CAMs are integrins which are linked to BL components
integrins attached to attachment plaques inside the cell
attachment plaque linked to keratin filaments
meant to be a strong attachment for the cells to the BL
Describe focal adhesions.
CAMs are integrins which are attached to actin filaments
Function: adhesion and mechanosensitivity
junction between epithelial cells and the basal lamina
What are the three domains of an epithelial cell?
apical domain
lateral domain
basal domain
Describe tight junctions, where they are located, and what they do.
In the lateral domain above the adherens junction. Also called the zonula occludens. No CAMs are used, transmembrane proteins from each cell reach out to each other.
These establish polarity or functional domains in the cell. May prevent membrane proteins from migrating.
What are gap junctions?
Transmembrane proteins that allow cells to communicate. Connection proteins are called connexons and they create central pores. Very regulated communication. Also called communication junctions or nexus. Located in lateral domain but under the adherens junction.
