Lecture 2: Epithelium, Connective Tissue and Cell Junctions

Q: What is epithelium?

A: Tissue that covers body surfaces, lines cavities, and forms glands.

Q: What are the 6 functions of epithelium?

A: Protection, Absorption, Secretion, Filtration, Excretion, Sensory perception.

Q: Why is epithelium described as avascular?

A: It contains no blood vessels.

Q: Which structure attaches epithelium to underlying connective tissue?

A: Basal lamina.

Q: Why does epithelial tissue heal quickly?

A: High regenerative capacity.

Q: What is a simple epithelium?

A: One cell layer thick.

Q: What is a stratified epithelium?

A: Two or more cell layers thick.

Q: What is a pseudostratified epithelium?

A: Appears multilayered but is actually one layer.

Q: What does squamous mean?

A: Flat, thin cells.

Q: What does cuboidal mean?

A: Cube-shaped cells.

Q: What does columnar mean?

A: Cells taller than they are wide.

Q: What is transitional epithelium specialised for?

A: Stretching and changing shape.

Q: Function of microvilli?

A: Increase surface area for absorption.

Q: Function of cilia?

A: Move mucus or debris across the cell surface.

Q: Function of keratin?

A: Protection against physical, chemical and microbial damage.

Q: What are the three major cell junctions?

A: Tight junctions, desmosomes, gap junctions.

Q: Function of tight junctions?

A: Form a seal and prevent substances passing between cells.

Q: Function of desmosomes?

A: Provide mechanical strength and prevent cells pulling apart.

Q: Function of gap junctions?

A: Allow communication between neighbouring cells.

Q: Match the junction to its function.

Tight junction → Seal

Desmosome → Strength

Gap junction → Communication

Q: What are the 4 major tissue types in the body?

Epithelial

Connective

Muscle

Nervous

Q: What are the 3 components of connective tissue?

Cells

Fibres

Ground substance

Q: What is extracellular matrix (ECM)?

A: Fibres + ground substance outside cells.

Q: What are the 3 connective tissue fibre types?

• Collagen

• Elastic

• Reticular

Q: Function of collagen fibres?

Strength

Q: Function of elastic fibres?

A: Stretch and recoil.

Q: Function of reticular fibres?

A: Supportive framework.

Q: Explain the relationship between epithelial tissue, cell junctions and connective tissue.

Epithelium covers surfaces and lines cavities.

Cells are tightly packed and joined by junctions.

Tight junctions = seal.

Desmosomes = strength.

Gap junctions = communication.

Epithelium sits on a basal lamina.

Underneath lies connective tissue.

Connective tissue supplies nutrients because epithelium is avascular.

Connective tissue consists of cells, fibres and ground substance.

Main fibres: collagen (strength), elastic (recoil), reticular (support).

Q: Which connective tissue cell produces fibres and ground substance?

Fibroblast