Histology: Epithelium, Muscle, and Nervous Tissue

Histology I: Epithelium, Muscle, and Nervous Tissue

Introduction

• Histology: The study of tissues.

• Cytology: The study of cells.

• Tissue: A group of cells that work together to perform specific functions.

Preparation

• Print off Building Grid #1.

• Gather materials:

  • Playdough or clay

  • Colored pencils/markers

  • Lab 2 instructions.

Tissue Categories

• Epithelium:

  • Body surfaces, lines cavities, and glands.

• Connective Tissue:

  • Connects and supports body parts; fills in spaces.

• Muscle:

  • Contains excitable and contractible elements.

• Nervous:

  • Composed of excitable communication cells.

Process Overview

• Examine the general characteristics of each tissue type:

  • Epithelium

  • Muscle

  • Nervous

• For each tissue example, complete the following:

  • Use e-texts & handouts to fill in a provided table.

  • Draw a picture of the tissue.

  • Build a model in clay.

  • Virtually examine the tissue in "A&P Revealed".

Characteristics of Epithelium

• Small cells, closely packed together.

• Contains an apical or luminal surface.

• Avascular: No blood supply.

• Supported by a basement membrane.

Naming Epithelium

• Based on:

  • Number of Layers:

  • Simple: Single cell layer.

  • Stratified: Multiple cell layers.

  • Shape of the Cells:

  • Squamous: Flat.

  • Cuboidal: Square, cube-shaped.

  • Columnar: Taller than wide.

Epithelium Types

Simple Squamous Epithelium

• Structure Focus Points:

  • Cell membrane

  • Nucleus

  • Cytoplasm

• Function:

  • Very thin cells allowing easy movement of molecules.

  • Lines blood vessels (endothelium) and lymph vessels.

  • Found in alveoli of lungs.

Simple Cuboidal Epithelium

• Structure Focus Points:

  • Basement membrane

  • Apical/luminal surface

  • Nucleus

• Function:

  • Found in ducts and glands.

  • Absorbs fluids across the apical surface.

  • Secretes molecules.

  • Locations include the ovary, kidney, and endocrine glands.

Simple Columnar Epithelium

• Structure Focus Points:

  • Basement membrane

  • Apical/luminal surface

  • Goblet cells

  • Nucleus

• Function:

  • Two types: Ciliated and non-ciliated.

  • Ideal for secretion and absorption.

  • Non-ciliated lines the digestive tract (from stomach to colon).

  • Ciliated lines bronchioles and uterine tubes.

Stratified Squamous Epithelium

• Structure Focus Points:

  • Stratum Corneum

  • Stratum Basale

  • Layered stratified cells

• Function:

  • Composed of multiple layers.

  • Protects against abrasion and friction.

  • Can be keratinized (skin) or non-keratinized (vagina).

  • Apical cells are squamous in shape; basal cells are cuboidal.

  • Continually replace dead cells.

Muscle Tissue

General Characteristics

• Characteristics:

  • Contractible elements (can shorten and contract).

  • Excitable (can produce electric impulses).

• Three Types of Muscle:

  • Skeletal Muscle

  • Cardiac Muscle

  • Smooth Muscle

Skeletal Muscle

• Structure Focus Points:

  • Striations (alternating light and dark bands)

  • Nuclei located peripherally and multinucleate.

• Functions:

  • Striated muscle composed of long, cylindrical fibers in bundles.

  • Under voluntary control.

Cardiac Muscle

• Structure Focus Points:

  • Y-shaped cells

  • Intercalated disks (specialized gap junctions)

  • Weak striations

• Function:

  • Forms the middle layer of heart walls.

  • Short fibers that often branch (Y-shaped).

  • Involuntary control.

Smooth Muscle

• Structure Focus Points:

  • Large, football-shaped nuclei.

  • No striations present.

• Function:

  • Composed of long, smooth fibers.

  • Facilitates involuntary movements of substances through the stomach, intestines, and uterus.

Nervous Tissue

Overview

• Cell Types:

  • Axons: Long processes responsible for transmitting signals.

  • Dendrites: Short processes that receive signals.

• Characteristics:

  • Excitable: Capable of carrying electric potentials.

Activities

• For each tissue type:

  • Draw the respective tissue in the provided chart in lab instructions.

  • Build a model using clay and add it to your Building Grid.

  • Utilize "A&P Revealed" for virtual examination and study of each tissue type.