Untitled Flashcard Set
1. How do the epithelial cell nuclei vary based on cell shape?
Columnar cells → elongated nuclei
Squamous cells → flattened nuclei
Cuboidal/pyramidal cells → spherical nuclei
2. Where is the basement membrane located? How do nutrients reach the epithelial cells?
Location: At the interface between epithelial cells and connective tissue.
Nutrients: Diffuse across the basement membrane from blood vessels in the lamina propria.
3. What structures can enter/not enter the basement membrane?
Nerve fibers: can penetrate.
Blood capillaries: do not enter epithelia.
4. What is a Lamina propria and what does it contain?
A layer of connective tissue under most epithelia.
Contains blood vessels that provide nutrients and oxygen to epithelial cells.
5. What is polarity of an epithelial cell? What are the two poles of an epithelial cell and their location?
Polarity = uneven distribution of organelles and membrane proteins.
Basal pole: contacts ECM and connective tissue.
Apical pole: opposite end, faces a space (lumen or external surface).
6. What is the role of a lateral surface in an epithelial cell?
Lateral surfaces adjoin neighboring cells, providing adhesion and communication.
7. Give the broad classification of epithelia.
Covering (lining) epithelia.
Secretory (glandular) epithelia.
8. What is the role of covering epithelia?
Cover surfaces or line cavities/organs.
Protect, absorb, or act as barriers.
9. How does simple epithelia differ from stratified epithelia?
Simple: 1 cell layer.
Stratified: 2 or more cell layers.
10. How is simple epithelia classified based on cell shape? Give their characteristics.
Squamous → thin, flat.
Cuboidal → height ≈ width, organelle-rich for active transport.
Columnar → taller than wide, often with cilia/microvilli, specialized for absorption.
11. What are the key features of simple squamous epithelium? Where are they commonly present?
Single thin cell layer, nuclei most visible.
Specialized for lining vessels and cavities, exchange of substances.
Present in renal loops of Henle, outer intestine wall, cornea, blood vessels (endothelium), body cavities (mesothelium), lung alveoli.
12. Give any two locations in the body and eye where simple squamous epithelium is present.
Body: kidney glomerulus, blood vessels.
Eye: corneal endothelium, trabecular endothelium.
13. Differentiate between an endothelium and mesothelium. Give the role of mesothelium.
Endothelium: lines blood vessels.
Mesothelium: lines large body cavities.
Role: secretes serous fluid (lubricant).
14. Key features, location & function:
Simple Cuboidal: Cells as tall as wide; transport functions.
Location: renal tubules, gland ducts, ciliary body epithelium.
Function: secretion, absorption, active transport.
Simple Columnar: Taller than wide, nuclei basal, often with cilia/microvilli.
Location: renal collecting duct, intestine.
Function: absorption, secretion.
Stratified Squamous: Multiple layers, protective.
Location: skin, oral cavity.
Nonkeratinized Stratified Squamous: Retains nuclei, protective.
Location: esophagus, cornea.
Stratified Cuboidal: 2 layers, extra protection.
Location: sweat gland ducts.
Transitional (Urothelium): Surface umbrella cells, distensible.
Location: urinary tract, bladder.
Function: protection from urine.
Pseudostratified: Appears layered but all touch basement membrane.
Location: respiratory tract.
Function: mucus movement with cilia.
15. What are the key features of keratinized cells?
Lost nuclei/organelles.
Flattened squames.
Impede water loss, form protective layer.
16. What is the role of umbrella cells?
Dome-like surface cells in transitional epithelium.
Protect underlying tissue from toxic urine; allow bladder distension.
17. What are the 5 components of junctional complex?
Tight junctions – seal, prevent leakage.
Adherens junctions – stabilize, hold cells.
Desmosomes – strong adhesion.
Gap junctions – intercellular communication.
Hemidesmosomes – attach cells to basal lamina.
18. What exchange happens at the gap junctions? Differentiate connexons and connexins.
Exchange: nutrients, ions, signal molecules.
Connexon: channel structure.
Connexins: protein subunits (6 per connexon).
19. What are microvilli? Give their location and role.
Small projections on apical surface.
Increase absorption surface area.
Location: intestinal epithelium.
20. What are cilia and where are they commonly found?
Motile apical structures with 9+2 microtubules.
Move mucus or sperm.
Found in respiratory tract, fallopian tubes.
21. What is a primary cilium? Give its contents and function.
Non-motile apical projection with 9+0 microtubules.
Enriched with receptors/signaling complexes.
Function: sensory detection (light, odor, motion, fluid flow).
22. How does motile cilia differ from non-motile cilia?
Motile: 9+2 structure, movement function.
Non-motile (primary cilium): 9+0, sensory role.
23. What are glands comprised of? What are the different products secreted?
Glands = secretory epithelia.
Products: proteins, lipids, glycoproteins, water/electrolytes.
24. What are unicellular glands? Example and product.
Single secretory cell.
Example: goblet cell.
Product: mucus.
25. What do the cytoplasm of goblet cells contain? How is mucus formed?
Contains: basal nucleus, RER, large Golgi, apical secretory granules.
Mucus = hydrated mucin after exocytosis.
26. Differentiate between endocrine and exocrine glands.
Endocrine: ductless, secrete hormones to blood.
Exocrine: ducts, secrete to organ surface/lumen.
27. How are exocrine glands classified? Locations?
By duct branching: simple (colon, uterus, skin glands), compound (salivary, pancreas, Brunner’s glands).
By shape: tubular, acinar, tubuloacinar.
28. Feature of compound tubular gland? Types & locations.
Several elongated coiled units with ducts converging.
Examples: Brunner’s glands (duodenum).
29. Three types of secretion by exocrine glands + examples:
Merocrine: exocytosis (most glands, salivary, pancreas).
Holocrine: cell disintegration (sebaceous glands).
Apocrine: loss of apical cytoplasm (mammary glands).
30. Differentiate Holocrine vs Apocrine secretion.
Holocrine: whole cell disintegrates.
Apocrine: only apical cytoplasm pinched off.
31. Features, location, product, role of special cells:
Serous cells: Pyramidal, apical secretory granules, basal RER. → Secrete proteins/enzymes. → Exocrine pancreas.
Mucous cells: Larger, flattened nuclei, mucinogen granules. → Secrete mucus. → Salivary glands.
Myoepithelial cells: Contractile, at basal ends of secretory units. → Propel secretions. → Sweat, salivary, mammary glands.
Melanocytes: In basal epithelium. → Transfer melanin pigment to keratinocytes. → Skin, conjunctiva.
Langerhans cells: Antigen-presenting cells. → Found in skin, conjunctiva, peripheral cornea.