Epithelial Tissues

Epithelial Tissues Study Notes

Lab Overview

  • Course: BI 151: Lab for Anatomy & Physiology I, SUNY Erie

  • Focus: Epithelial tissues

  • Instruction: Complete the chart in the handout after the first practical.

  • FAQ:

    • Question: Will connective tissues, muscle tissues, or nervous tissues be examined in the first practical?

    • Answer: Only connective tissue (hyaline cartilage), muscle tissue (skeletal), or nervous tissue from LAB 2 may appear in the first practical.

Definitions of Epithelial Tissue

  • Refer to pages 117-119 in the textbook for detailed definitions.

General Characteristics of Epithelial Tissue

  • Cellular Arrangement:

    • Cells fit closely together to form membranes or sheets of cells.

  • Intercellular Substance:

    • Small quantities of intercellular substance located between cells.

  • Polarity:

    • One free apical surface is present.

  • Basement Membrane:

    • Consists of basal lamina and reticular lamina.

  • Avascular:

    • Blood vessels are absent; nutrients supplied by diffusion.

  • Cell Division:

    • High rate of cell division allowing for quick regeneration.

Functions of Epithelial Tissue

  • Simple Epithelium Functions:

    • Absorption of nutrients and water (e.g., gastrointestinal tract).

    • Diffusion of gases (e.g., lungs).

    • Secretion of fluids (e.g., serous fluid).

    • Filtration (e.g., filtration of blood plasma in kidneys).

  • Stratified Epithelium Function:

    • Provides protection (e.g., epidermis of skin).

Classification of Epithelial Tissue

  • Simple Epithelium:

    • A single layer of cells.

  • Stratified Epithelium:

    • Multiple layers of cells.

  • Pseudostratified Epithelium:

    • A single layer that appears stratified (literally translates to "falsely stratified").

Cell Shapes in Epithelial Tissue

  • Squamous:

    • Flat and scale-like cells.

  • Cuboidal:

    • Cube-shaped cells.

  • Columnar:

    • Cells in which height exceeds the width (column-shaped).

Epithelial Tissues Overview Chart

  • Instruction: Fill out the rows in the “Tissues” handout according to information on the provided cards. Only entries for epithelial tissues should be completed due to the focus of this lab.

Specific Types of Epithelial Tissue

A. Simple Squamous Epithelium

  • Category: Epithelial tissue

  • Location: Lines air sacs (alveoli) of lungs.

  • Characteristics/Description:

    • Composed of a single layer of flat cells.

    • Cells are closely packed with no matrix present.

    • Avascular (blood vessels absent).

  • Function(s):

    • Covers/lines surfaces.

    • Allows for passage of materials (e.g., diffusion) due to the single layer.

B. Simple Cuboidal Epithelium

  • Category: Epithelial tissue

  • Location: Lines kidney tubules.

  • Characteristics/Description:

    • Comprises a single layer of "cube-like" cells.

    • Cells are closely packed with no matrix present.

    • Avascular.

  • Function(s):

    • Covers/lines surfaces.

    • Facilitates passage of materials (e.g., secretion, filtration) due to the single layer.

C. Simple Columnar Epithelium (Non-Ciliated)

  • Category: Epithelial tissue

  • Location: Lines digestive tract (particularly small intestine).

  • Characteristics/Description:

    • Composed of a single layer of "tall" cells.

    • May include mucous-secreting Goblet cells.

    • No cilia present.

    • Cells are closely packed with no matrix.

    • Avascular.

  • Function(s):

    • Covers/lines surfaces.

    • Allows for absorption of materials due to being one layer thick.

D. Pseudostratified Epithelium (Ciliated)

  • Category: Epithelial tissue

  • Location: Lines the trachea.

  • Characteristics/Description:

    • Comprises a single layer of differing cells (both columnar ciliated cells and Goblet cells).

    • All cells contact the basement membrane but not all reach the free surface.

    • Closely packed cells without matrix; avascular.

  • Function(s):

    • Covers/lines the surfaces.

    • Production of mucous and propulsion of mucous by cilia (protecting air sacs by trapping particles).

Goblet Cells

  • Reference: See figure 4.6 on page 124 in the textbook.

  • Note: Goblet cells are illustrated as “1” in diagrams for Simple Columnar and Pseudostratified Epithelium, but they do not have a specific row in the “Tissues” chart.

E. Stratified Squamous Epithelium

  • Category: Epithelial tissue

  • Location: Epidermis of skin and lining of the oral cavity.

  • Characteristics/Description:

    • Comprises several layers of cells; surface cells are flat.

    • Cells on the basement membrane are living and undergo mitosis, while the outermost cells that are flat are dead.

    • Closely packed cells with no matrix present; avascular.

  • Function(s):

    • Covers/lines surfaces.

    • Provides protection due to the stratified layers.