Unit 2 Study Guide: Tissues and Integumentary System

Key Vocabulary

Essential Terms in Anatomy & Physiology

This section covers foundational terminology for understanding tissues and the integumentary system. Mastery of these terms is crucial for success in Anatomy & Physiology.

• Endothelium: The thin layer of cells lining the interior surface of blood vessels and lymphatic vessels.

• Mesothelium: The epithelial layer lining body cavities such as the pleura, pericardium, and peritoneum.

• Exocrine gland: Glands that secrete substances onto an epithelial surface via ducts (e.g., sweat glands).

• Endocrine gland: Glands that release hormones directly into the bloodstream (e.g., thyroid gland).

• Apical surface: The surface of an epithelial cell that faces away from the basement membrane.

• Basal surface: The surface of an epithelial cell that faces the basement membrane.

• Basal lamina: A layer of extracellular matrix secreted by the epithelial cells, on which the epithelium sits.

• Basement membrane: A thin, fibrous, extracellular matrix that separates the epithelium from underlying tissue.

• Avascular: Lacking blood vessels; characteristic of epithelial tissue.

• Holocrine secretion: A type of exocrine secretion where the entire cell disintegrates to release its product (e.g., sebaceous glands).

• Merocrine/Eccrine secretion: Secretion by exocytosis without loss of cellular material (e.g., sweat glands).

• Apocrine secretion: Secretion involving loss of part of the cell's cytoplasm (e.g., mammary glands).

• Goblet cells: Unicellular glands that secrete mucus, found in respiratory and intestinal tracts.

• Lacunae: Small spaces within bone or cartilage that house cells such as osteocytes or chondrocytes.

• Canaliculi: Microscopic canals between the lacunae of ossified bone.

• Osteocytes: Mature bone cells found in lacunae.

• Keratinocytes: The primary cell type in the epidermis, responsible for producing keratin.

• Chondrocytes: Cells found in cartilage tissue.

• Fibroblasts: Cells that produce collagen and other fibers in connective tissue.

• Dendrites: Branch-like extensions of neurons that receive signals.

• Axons: Long, slender projections of neurons that transmit electrical impulses.

• Epidermis: The outermost layer of skin.

• Dermis: The layer of skin beneath the epidermis, containing connective tissue, blood vessels, and nerves.

• Subcutaneous: The layer beneath the dermis, also called the hypodermis; contains fat and connective tissue.

• Integument: The skin and its accessory structures.

• Dermal papillae: Projections of the dermis that interlock with the epidermis, increasing surface area for exchange.

• Epidermal ridges: Downward waves of epidermis between dermal papillae; contribute to fingerprints.

• Melanin: Pigment produced by melanocytes, responsible for skin color.

• Melanocytes: Cells in the basal layer of the epidermis that produce melanin.

• Melanosomes: Organelles within melanocytes where melanin is synthesized and stored.

• Carotene: A yellow-orange pigment found in the skin.

• Tension lines: Patterns of collagen fibers in the dermis; important for surgical incisions.

• Keratin: A tough, fibrous protein produced by keratinocytes.

• Sebum: Oily secretion produced by sebaceous glands.

• Eponychium: The cuticle; skin at the base of the nail.

• Hyponychium: Skin beneath the free edge of the nail.

• Granulation tissue: New connective tissue and microscopic blood vessels that form on the surfaces of a wound during healing.

• Keloid: Excessive scar tissue formation.

• Inflammation: The body's response to injury or infection, characterized by redness, heat, swelling, and pain.

• Perichondrium: Dense layer of connective tissue surrounding cartilage.

Key Concepts

• Functions and Locations of Major Tissue Types

Understanding the four main tissue types—epithelial, muscle, connective, and nervous—is fundamental in Anatomy & Physiology. Each type has unique functions and locations in the body.

• Epithelial Tissue

  • Functions: Protection, absorption, filtration, excretion, secretion, and sensory reception.

  • Locations: Covers body surfaces, lines cavities and hollow organs, forms glands.

  • Glands: Specialized epithelial cells that secrete substances; classified as exocrine (with ducts) or endocrine (ductless).

  • Examples in Skin: Sweat glands (exocrine), sebaceous glands (exocrine).

• Muscle Tissue al muscles (attached to bones), cardiac muscle (heart), smooth muscle (walls of hollow organs).

  • Unique Characteristics: Contractility, excitability, extensibility, elasticity.

• Connective Tissue

  • Functions: Support, protection, insulation, transportation of substances.

  • Locations: Found throughout the body; examples include bone, cartilage, adipose, blood.

  • Structure-Function Relationship: The composition of fibers and ground substance determines the tissue's properties (e.g., bone is rigid due to mineralization).

• Nervous Tissue

  • Functions: Transmit electrical impulses, process information.

  • Cell Types: Neurons (conduct impulses), neuroglia (support neurons).

  • Major Parts of a Neuron: Cell body (soma), dendrites, axon.

Shapes and Strata of Epithelial Tissue

Classification and Functional Relationships

Epithelial tissues are classified by cell shape and number of layers (strata). These features relate directly to their function.

• Cell Shapes: Squamous (flat), cuboidal (cube-shaped), columnar (tall).

• Strata: Simple (one layer), stratified (multiple layers), pseudo-stratified (appears layered but is not).

• Functional Example: Simple squamous epithelium in lung alveoli allows rapid gas exchange due to thinness.

Types of Intercellular Connections

Cell Junctions and Their Roles

Intercellular connections maintain tissue integrity and facilitate communication.

• Tight junctions: Prevent leakage between cells.

• Gap junctions: Allow passage of ions and small molecules for cell communication.

• Desmosomes: Provide strong adhesion between cells.

• Hemidesmosomes: Anchor cells to the basement membrane.

• Intercalated discs: Specialized connections in cardiac muscle for synchronized contraction.

Major Cell Types in Tissues

Identification and Function

• Keratinocytes: Epidermal cells producing keratin.

• Osteocytes: Mature bone cells.

• Chondrocytes: Cartilage cells.

• Fibroblasts: Connective tissue cells producing fibers.

• Adipocytes: Fat cells.

• Melanocytes: Pigment-producing cells in skin.

• Dendritic cells: Immune cells in skin and other tissues.

Connective Tissue Types and Subcategories

Classification and Fiber Types

Connective tissue is divided into three main categories, each with distinct functions and structures.

• Connective Tissue Proper: Loose (areolar, adipose, reticular) and dense (regular, irregular, elastic).

• Fluid Connective Tissue: Blood and lymph.

• Supporting Connective Tissue: Cartilage and bone.

• Fibers: Collagen (strength), elastic (flexibility), reticular (support).

Growth in Cartilage and Bone

Appositional vs Interstitial Growth

• Appositional growth: Addition of new layers on the surface.

• Interstitial growth: Expansion from within the tissue.

Tissue Membranes

Types and Functions

• Mucous membranes: Line body cavities open to the exterior; secrete mucus.

• Serous membranes: Line closed cavities; secrete serous fluid.

• Cutaneous membrane: The skin; protects the body.

• Synovial membranes: Line joint cavities; secrete synovial fluid.

Features of Epidermal Layers

Layer Identification and Function

• Stratum corneum: Outermost, dead keratinized cells.

• Stratum lucidum: Clear layer found in thick skin (palms, soles).

• Stratum granulosum: Granular cells, keratin formation begins.

• Stratum spinosum: Spiny appearance, provides strength.

• Stratum basale: Deepest layer, mitotically active cells.

Integumentary System Functions

Protection and Homeostasis

• Protection against mechanical injury, pathogens, and UV radiation.

• Regulation of body temperature.

• Sensation (touch, pain, temperature).

• Excretion of wastes.

• Synthesis of vitamin D3.

Thick vs Thin Skin

Major Differences and Locations

• Thick skin: Found on palms and soles; contains stratum lucidum, more layers of stratum corneum.

• Thin skin: Covers most of the body; lacks stratum lucidum, fewer layers.

Major Structures of Skin and Accessory Structures

Hair, Nails, Glands, and Touch Receptors

• Accessory structures: Hair follicles, nails, sweat glands, sebaceous glands, sensory receptors.

• Hypodermis/Subcutaneous layer: Provides insulation, energy storage, and cushioning.

Skin Cancer

Major Types

• Basal cell carcinoma: Most common, least dangerous.

• Squamous cell carcinoma: May metastasize.

• Melanoma: Most dangerous, arises from melanocytes.

Skin Color

Pigments and Their Roles

• Carotenoids: Yellow-orange pigments from diet.

• Melanin: Brown-black pigment produced by melanocytes.

Layers of the Dermis

Papillary vs Reticular Layer

• Papillary layer: Superficial, loose connective tissue, contains dermal papillae.

• Reticular layer: Deep, dense irregular connective tissue, provides strength and elasticity.

Touch Receptors

Types, Locations, and Sensations

Receptor Type	Location	Sensation
Meissner's corpuscles	Dermal papillae	Light touch
Pacinian corpuscles	Deep dermis/hypodermis	Pressure/vibration
Merkel cells	Stratum basale	Fine touch
Ruffini endings	Dermis	Stretch
Free nerve endings	Epidermis/dermis	Pain, temperature

Structure of Hair and Hair Follicle

Components and Growth Cycle

• Shaft: Visible part above skin.

• Root: Embedded in skin.

• Cuticle: Outermost layer of hair.

• Arrector pili: Muscle causing hair to stand up.

• Hair Growth Cycle: Anagen (growth), catagen (regression), telogen (resting).

Changes to Skin with Aging

Age-Related Alterations

• Thinner epidermis and dermis.

• Reduced collagen and elastin.

• Decreased melanocyte activity.

• Slower wound healing.

Vitamin D3 Production

Role of Skin in Synthesis

• UV radiation converts 7-dehydrocholesterol in skin to vitamin D3 (cholecalciferol).

• Vitamin D3 is essential for calcium absorption and bone health.

Repair of Integument

Steps of Skin Regeneration After Injury

• Inflammation: Increased blood flow, immune response.

• Migration: Epithelial cells migrate to cover wound.

• Proliferation: New tissue forms (granulation tissue).

• Maturation: Remodeling and strengthening of tissue.

Key Skills

Essential Abilities for Exam Success

• Recognize and differentiate epithelial tissue types.

• Distinguish between burn types (first, second, third degree).

• Sequence events of skin regeneration and tissue injury.

• Compare and contrast the four main tissue types.

• Identify and describe major microscope types and their uses.

• Label layers of the epidermis and dermis.

• Compare and contrast three muscle types (skeletal, cardiac, smooth).

Study Tips

Strategies for Effective Learning

• Complete review questions at the end of each chapter.

• Utilize online resources such as Pearson myLab for practice and interactive learning.

• Quiz yourself or have someone quiz you on key terms.

• Make and use flash cards.

• Draw and label diagrams for visual learning.

• Practice sequencing events and processes aloud or in writing.

Additional info: Some definitions and examples have been expanded for academic completeness. Table of touch receptors inferred from standard textbook content.