🧬 EPITHELIAL & CONNECTIVE TISSUES

Intro to Anatomy & Physiology – Detailed Study Guide

🧱 I. TISSUES: BASIC OVERVIEW

Tissue = a group of similar cells working together to perform a specific function.

Four basic tissue types:

  1. Epithelial

  2. Connective

  3. Muscle

  4. Nervous

This guide focuses on epithelial and connective tissues.

🧬 II. EPITHELIAL TISSUE

🔹 Definition

Epithelial tissue covers body surfaces, lines cavities, and forms glands.

⭐ A. General Characteristics of Epithelial Tissue

(You WILL be tested on these)

All epithelial tissues:

  • Are made of tightly packed cells

  • Have very little extracellular matrix

  • Show cellularity (many cells)

  • Are polar

    • Apical surface (free surface)

    • Basal surface (attached)

  • Are attached to a basement membrane

  • Are avascular (no blood vessels)

  • Are innervated (have nerves)

  • Have a high rate of cell division (regenerate quickly)

🔹 B. Functions of Epithelial Tissue

  • Protection

  • Absorption

  • Filtration

  • Secretion

  • Sensory reception

🔹 C. Structural Terms to Know

  • Apical surface: faces outside or a cavity

  • Basal surface: attached to basement membrane

  • Basement membrane: anchors epithelium to connective tissue

  • Lumen: hollow space inside an organ

🧬 D. Types of Epithelial Tissue

1⃣ Simple Squamous Epithelium

Structure:

  • One layer of flat cells

Function:

  • Diffusion

  • Filtration

Locations:

  • Alveoli of lungs

  • Capillaries

  • Kidney glomeruli

📌 Thin = fast diffusion

2⃣ Stratified Squamous Epithelium

Structure:

  • Many layers of flat cells

Function:

  • Protection

Locations:

  • Epidermis (keratinized)

  • Mouth, esophagus (non-keratinized)

📌 Multiple layers = protection

3⃣ Simple Cuboidal Epithelium

Structure:

  • One layer of cube-shaped cells

Function:

  • Secretion

  • Absorption

Locations:

  • Kidney tubules

  • Glands

4⃣ Simple Columnar Epithelium

Structure:

  • One layer of tall cells

  • May have microvilli or cilia

Function:

  • Absorption

  • Secretion

Locations:

  • Digestive tract

  • Gallbladder

5⃣ Pseudostratified Columnar Epithelium

Structure:

  • Appears multilayered

  • Actually a single layer

  • Often ciliated

Function:

  • Secretion

  • Moves mucus

Location:

  • Trachea

  • Upper respiratory tract

6⃣ Transitional Epithelium

Structure:

  • Cells change shape when stretched

Function:

  • Allows stretching

Location:

  • Urinary bladder

🧬 III. CONNECTIVE TISSUE

🔹 Definition

Connective tissue supports, binds, protects, and transports.

⭐ A. General Characteristics of Connective Tissue

Connective tissues consist of:

  • Cells

  • Extracellular matrix, which includes:

    • Fibers (collagen, elastic, reticular)

    • Ground substance

📌 Most connective tissues are vascular

Exceptions: cartilage, ligaments, tendons

🔹 B. Functions of Connective Tissue

  • Support

  • Protection

  • Binding

  • Transport

  • Storage

  • Immune defense

🧱 C. Types of Connective Tissue

🔹 1. CONNECTIVE TISSUE PROPER

A. Loose Connective Tissue

Areolar Tissue

  • Function: binds tissues, holds organs

  • Location: under epithelium, around organs

Adipose Tissue

  • Function: insulation, energy storage

  • Location: under skin, around organs

Reticular Tissue

  • Function: framework for organs

  • Location: lymph nodes, spleen

B. Dense Connective Tissue

Dense Regular

  • Function: strong attachment

  • Location: tendons, ligaments

Dense Irregular

  • Function: strength in many directions

  • Location: dermis of skin

Elastic Connective Tissue

  • Function: stretch and recoil

  • Location: large arteries

🔹 2. CARTILAGE (Avascular)

Type

Function

Location

Hyaline

Support & flexibility

Trachea, nose

Elastic

Maintains shape

Ear

Fibrocartilage

Shock absorption

Intervertebral discs

🔹 3. BONE (OSSEOUS TISSUE)

  • Function: support, protection, blood cell formation

  • Cells: osteocytes

  • Matrix: calcium & collagen

  • Location: skeleton

🔹 4. BLOOD

  • Function: transport

  • Components:

    • Red blood cells

    • White blood cells

    • Platelets

    • Plasma

📌 Blood is connective tissue because it has cells + matrix

🧠 IV. EXAM & LAB TIPS (Intro A&P)

  • Know structure → function

  • Identify tissues from microscope slides

  • Know locations

  • Understand vascular vs avascular

  • Be able to compare epithelial vs connective

🧪 V. PRACTICE QUESTION

Why is epithelial tissue avascular?

👉 It receives nutrients by diffusion from underlying connective tissue.