Study Guide: Tissues and Membranes in Anatomy & Physiology

Chapter 4: Tissues and Membranes

Introduction to Tissues

Tissues are groups of cells with similar structure and function, working together to perform specific activities in the body. Understanding the types, functions, and characteristics of tissues is fundamental in Anatomy & Physiology.

Basic Definitions

• Tissue: A group of similar cells and their extracellular matrix that perform a specific function.

• Histology: The study of tissues at the microscopic level.

Four Basic Types of Tissues

The human body contains four primary tissue types, each with distinct functions:

Tissue Type	General Function
Epithelial	Covers body surfaces, lines cavities, forms glands; protection, absorption, secretion
Connective	Supports, binds, and protects organs; stores energy; provides immunity
Muscle	Produces movement through contraction
Nervous	Receives, transmits, and processes nerve impulses

Epithelial Tissue

Epithelial tissue forms the covering of all body surfaces, lines body cavities and hollow organs, and is the major tissue in glands.

• Epithelium: A sheet of cells that covers a body surface or lines a body cavity.

• Glands: Structures made of epithelial cells that secrete substances.

Common Characteristics of Epithelial Tissue

• Cells are closely packed with minimal extracellular material.

• Exhibit polarity (apical and basal surfaces).

• Avascular but innervated (no blood vessels, but has nerves).

• High regenerative capacity.

Functions of Epithelial Tissue

• Protection (e.g., skin protects underlying tissues)

• Absorption (e.g., intestinal lining absorbs nutrients)

• Secretion (e.g., glands secrete hormones, enzymes)

• Sensation (e.g., sensory receptors in skin)

Cell Junctions in Epithelial Tissue

• Tight Junctions: Prevent leakage of extracellular fluid.

• Desmosomes: Anchor cells together, providing mechanical strength.

• Gap Junctions: Allow communication between adjacent cells.

Specialized Structures

• Microvilli: Increase surface area for absorption (e.g., in intestines).

• Cilia: Move substances across the cell surface (e.g., respiratory tract).

Classification of Epithelia

Epithelia are classified by the number of cell layers and the shape of cells.

• Simple Epithelium: One cell layer; functions in absorption, secretion, filtration.

• Stratified Epithelium: Multiple layers; functions in protection.

Cell Shape	Brief Description
Squamous	Flat, scale-like
Cuboidal	Cube-shaped
Columnar	Tall, column-like

Types of Epithelia

• Simple squamous: Single layer of flat cells; allows diffusion and filtration.

• Simple cuboidal: Single layer of cube-shaped cells; secretion and absorption.

• Simple columnar: Single layer of tall cells; absorption and secretion.

• Stratified squamous: Multiple layers of flat cells; protection.

• Pseudostratified columnar: Appears layered but is not; secretion and movement of mucus.

• Transitional: Varies in appearance; stretches readily (e.g., urinary bladder).

Components of Connective Tissue

• Cells: Fibroblasts, adipocytes, immune cells, etc.

• Fibers: Collagen, elastic, reticular

• Ground Substance: Non-cellular material in which cells and fibers are embedded

Functions of Connective Tissue

• Support and structural framework

• Protection of organs

• Transport of fluids and dissolved materials

• Energy storage (adipose tissue)

Types of Connective Tissue

General Type	General Function	Types (Examples)
Connective Tissue Proper	Binding, support	Loose (areolar, adipose), Dense (regular, irregular)
Fluid Connective Tissue	Transport	Blood, lymph
Supporting Connective Tissue	Structural strength	Cartilage, bone

Epithelial Membranes

Epithelial Membrane	General Function	General Location
Mucous Membrane	Lines cavities open to exterior; secretes mucus	Digestive, respiratory, urinary tracts
Serous Membrane	Lines closed cavities; secretes serous fluid	Thoracic, abdominal cavities
Cutaneous Membrane	Protects body surface	Skin

Muscle Tissue

Muscle tissue is specialized for contraction, producing movement and force.

• Primary function: Movement of body and its parts

Muscle Tissue Type	Locations	Functions
Skeletal	Attached to bones	Voluntary movement
Cardiac	Heart	Pumps blood
Smooth	Walls of hollow organs	Involuntary movement

• Striated muscle types: Skeletal and cardiac

• Voluntary muscle type: Skeletal

Nervous Tissue

Nervous tissue is responsible for sensing stimuli and transmitting signals throughout the body.

• Primary function: Communication and control

• Cell types: Neurons (transmit impulses), neuroglia (support neurons)

Tissue Injury and Repair

• Phases of response: Inflammation and regeneration

• Four signs of inflammation: Redness, heat, swelling, pain

Effects of Aging on Tissues

• Decreased tissue regeneration

• Loss of elasticity and function

Additional info: Some content, such as specific examples and detailed descriptions, was inferred based on standard Anatomy & Physiology curriculum.