[RAP0 21LAB] PRELIM: Lesson 3 (Epithelial Cells)

Types of Cells in Human Anatomy: Epithelial Cells

Epithelial Cells

• Function: Protection, secretion, absorption.

• Examples: Skin cells, lining of the digestive tract.

• Special Feature: Tightly packed layers form barriers.

4 Characteristics of Epithelial Cells

1. Closely Packed

2. Polarity

3. Avascular

4. Regeneration

Closely Packed

• Characteristics of Epithelial Cells

• They are tightly joined together with minimal extracellular material.

Polarity

• Characteristics of Epithelial Cells

• Epithelial cells have distinct surfaces

Apical surface and Basal surface

2 Polarity of Epithelial Cells

Apical surface

• Polarity of Epithelial Cells

• Faces the lumen or external environment.

Basal surface

• Polarity of Epithelial Cells

• Anchored to the basement membrane, which separates the epithelium from underlying connective tissue

Avascular

• Characteristics of Epithelial Cells

• They lack blood vessels and rely on diffusion from nearby capillaries in the connective tissue for nutrients.

Regeneration

• Characteristics of Epithelial Cells

• Epithelial cells have a high capacity for renewal due to frequent wear and tear.

shape and arrangement

Epithelial cells are classified based on their ___ and ___.

Squamous; Cuboidal; Columnar

3 Epithelial cells by shape

Squamous

• Classification of Epithelial Cells by shape

• Flat, thin, and scale-like.

Cuboidal

• Classification of Epithelial Cells by shape

• Cube-shaped with equal width and height.

Columnar

• Classification of Epithelial Cells by shape

• Tall and cylindrical.

4 Epithelial cells by arrangement

• Simple Epithelium

• Stratified Epithelium

• Pseudostratified Epithelium

• Transitional Epithelium

Simple Epithelium

• Classification of Epithelial Cells by arrangement

• A single layer of cells.

Stratified Epithelium

• Classification of Epithelial Cells by arrangement

• Multiple layers of cells.

Pseudostratified Epithelium

• Classification of Epithelial Cells by arrangement

• Appears layered but all cells are attached to the basement membrane.

Transitional Epithelium

• Classification of Epithelial Cells by arrangement

• Found in the urinary bladder; capable of stretching.

5 Functions of Epithelial Cells

• Protection

• Absorption

• Secretion

• Excretion

• Sensation

Protection

• Functions of Epithelial Cells

• Acts as a barrier to protect underlying tissues from physical injury, pathogens, and dehydration (e.g., skin epithelium).

Absorption

• Functions of Epithelial Cells

• ___ nutrients and other substances (e.g., intestinal lining).

Secretion

• Functions of Epithelial Cells

• Produces and releases substances like mucus, enzymes, and hormones (e.g., glandular epithelium).

Excretion

• Functions of Epithelial Cells

• Removes waste products (e.g., sweat glands).

Sensation

• Functions of Epithelial Cells

• Contains nerve endings for sensory functions (e.g., in the skin, tongue, and nasal passages).

4 Examples of Epithelial Tissue in the Body

• Skin

• Lining of the digestive tract

• Respiratory tract

• Urinary system

Skin

• Examples of Epithelial Tissue in the Body

• Stratified squamous epithelium provides a protective barrier.

Lining of the digestive tract

• Examples of Epithelial Tissue in the Body

• Simple columnar epithelium aids in absorption and secretion.

Respiratory tract

• Examples of Epithelial Tissue in the Body

• Pseudostratified columnar epithelium with cilia traps and removes debris.

Urinary system

• Examples of Epithelial Tissue in the Body

• Transitional epithelium stretches to accommodate urine volume.