Lecture 7-Epithelium & Glands

Question 1

What is an occluding junctional complex (cell to cell)?

Answer 1

Zona occludens (tight junction)
1. Transmembrane proteins: claudins & occludins
2. Functions as a tight seal-allows for smaller particles to pass through between cells
3. Most APICAL

Question 2

Anchoring Junctional Complexes-Cell to cell (2)

Answer 2

1. Zonula Adherens
   Transmembrane protein: E-cadherin-Calcium dependent
   Fx: anchors cell to ECM through interaction w/ actin cytoskeleton
2. Macula Adherens-desmosome
   Transmembrane protein: Desmocollin &Desmoglein
   Intracellular plaque=Plakoglobin & Desmoplakins

Question 3

Communicating Junctional Complex-Cell to cell

Answer 3

1. GAP junctions
   Transmembrane protein: connexin-half of channel is formed by 6 connexin called connexons

Question 4

What is the reason for cell specializations on the lateral surface?

Answer 4

Increase surface area with places of infoldings called plicae
-common in cells engaged in fluid and electrolye transport (Small intestine)

Question 5

What are the two basement membrane specializations?

Transmembrane protein, clincal correlate

Answer 5

1. Focal Adhesions
   Transmembrane proteins=integrins-bind to actin
   Important role during cell migration
2. Hemidesmosomes
   Transmembrane protein=integrins
   Clinical correlate-Bollous pemphigoid-disease characterized by bliter formation d/t epithelia attachement to basement membrane. (Antibodies directed against BP230 and Type XVII collagen in basement membrane)

Question 6

What are the four components to the Basal Lamina?

Answer 6

1. Laminins
2. Type IV collagen
3. Proteoglycans
4. Glycoproteins

Question 7

Where do exocrine glands secrete to?

Answer 7

Directly onto the surface
1. Unicellular (goblet cells)
2. Multicellular-have parts that create a duct for the transport of the product

Question 8

Where do endocrine glands secrete their products?

Answer 8

Into connective tissue and then enter the bloodstream
-Paracrine: onto nearby cells
-Autocrine: onto same cell

Question 9

Exocrine Gland classification (multicellular)

Answer 9

1. Structure of the ducts: simple or compound (branched)
2. Shape-Tubular=tube, Alveolar (acinar)=flask, tubuloalveolar=tube ends in a dilation

Question 10

Modes of secretion for exocrine glands (3)

Answer 10

1. Merocrine (most common): exocytosis of membrane-bound vesicle
2. Apocrineproduct released at apical surface. Product is “pinched off”
3. Holocrinecell ruptures and releases secretory product & cell debris

Question 11

Classification of Exocrine glands based on secretion produced (3)

Answer 11

1. Serous-round nuclei-basophilic stained. Ex: Parotid salivary glands
2. Mucous-Pale staining (appear empty on H&E) nuclei within cells are flattened. Ex: palantine glands
3. Mixed-both mucous and serous. Ex: submandibular & sublingual salivary glands