Tissues and Integumentary System: Study Guide for Anatomy & Physiology

Tissues and Integumentary System

Histology

Histology is the study of tissues, which are groups of cells with similar structure and function. Understanding tissue types is fundamental in anatomy and physiology.

• Four Major Types of Tissue:

  • Epithelial: Covers surfaces, lines cavities, forms glands.

  • Connective: Supports, binds, and protects organs.

  • Muscle: Enables movement.

  • Nervous: Facilitates communication via electrical impulses.

• General Functions:

  • Epithelial: Provides protection.

  • Connective: Connects and supports.

  • Muscle: Produces movement.

  • Nervous: Communicates signals.

• Importance: Tissues matter because they perform essential functions for the body’s survival and health.

• Organ Composition: Most organs contain a mix of these tissue types.

Epithelial Tissue

Epithelial tissue lines body surfaces and cavities, and forms glands. It is classified by cell shape and number of layers.

• Five Specific Types:

  • Simple Squamous: Diffusion; found in alveoli, capillaries.

  • Stratified Squamous: Protection; found in skin, mouth, esophagus, vagina.

  • Simple Cuboidal: Secretion; found in glands, kidney tubules.

  • Simple Columnar: Absorption; found in intestines, stomach.

  • Pseudostratified Columnar: Secretion, movement; found in respiratory tract.

• Apical vs. Basal Surface: Apical faces exterior or cavity; basal attaches to connective tissue.

• Glandular Epithelium:

  • Exocrine glands: Secrete onto surfaces or into ducts.

  • Endocrine glands: Secrete hormones into bloodstream.

Connective Tissue

Connective tissue supports, binds, and protects other tissues and organs. It is the most diverse tissue type.

• Seven Specific Types:

  • Aerolar: Provides nutrients, found under epithelia.

  • Dense Irregular: Resists tension in many directions; found in skin.

  • Dense Regular: Resists tension in one direction; found in tendons, ligaments.

  • Adipose: Cushions, stores energy; found deep in skin.

  • Reticular: Supports lymphatic organs.

  • Blood: Transports nutrients, gases; found in vessels.

  • Bone: Supports, protects; found in skeleton.

  • Hyaline Cartilage: Supports, reduces friction; found in joints.

• Structural Elements: Specialized cells, ground substance, fibers.

Muscle Tissue

Muscle tissue is specialized for contraction and movement.

• Three Types:

  • Skeletal: Voluntary movement; attached to bones.

  • Cardiac: Involuntary; found in heart.

  • Smooth: Involuntary; found in organs, blood vessels.

Nervous Tissue

Nervous tissue is responsible for transmitting electrical impulses and processing information.

• Two Main Cell Types:

  • Neurons: Conduct impulses.

  • Neuroglia: Support and assist neurons.

Tissue Repair

Tissue repair involves restoring structure and function after injury.

• Types of Tissue Repair: Cartilage, skeletal, cardiac muscle.

• Regeneration vs. Fibrosis: Some tissues (e.g., neurons, cardiac muscle) have limited ability to regenerate; others repair by forming scar tissue (fibrosis).

• Key Factors: Inflammation, regeneration, presence of fibroblasts.

Integumentary System

Functions of the Integumentary System

The integumentary system protects the body, regulates temperature, and synthesizes vitamin D.

• Protection: Against pathogens, dehydration, and injury.

• Regulation: Temperature, excretion, sensory input.

• Storage: Lipids.

• Synthesis: Vitamin D.

Main Layers of the Integument

The skin consists of three main layers, each with distinct functions.

• Epidermis: Stratified squamous epithelium; avascular.

• Dermis: Areolar and dense irregular connective tissue; vascular.

• Hypodermis: Areolar tissue, adipose tissue; attaches skin to underlying muscle and bone.

Epidermis

The epidermis is the outermost layer of skin, providing a barrier and protection.

• Main Cell Types: Keratinocytes (produce keratin), melanocytes (produce melanin).

• Layers (from superficial to deep):

  • Stratum corneum

  • Stratum lucidum (only in thick skin)

  • Stratum granulosum

  • Stratum spinosum

  • Stratum basale

• Stratum Basale: Site of cell division; contains melanocytes.

• Stratum Corneum: Dead cells; provides protection.

Dermis

The dermis provides strength and elasticity to the skin and contains blood vessels, nerves, and glands.

• Main Layers:

  • Papillary layer: Areolar connective tissue; forms dermal papillae.

  • Reticular layer: Dense irregular connective tissue; provides strength.

• Dermal Papillae: Increase surface area for exchange between dermis and epidermis.

• Collagen and Tension Lines: Collagen fibers form tension lines; gaps between fibers allow skin movement.

Hypodermis

The hypodermis anchors the skin to underlying structures and provides insulation and energy storage.

• Main Tissue Types: Areolar and adipose tissue.

• Function: Attaches skin to muscle and bone.

Accessory Structures of the Skin

Accessory structures include hair, nails, and glands, each with specific functions.

• Hair: Protects, insulates, and aids in sensation.

• Nails: Protect fingertips; indicate health.

• Glands: Sebaceous (oil), sweat (eccrine/apocrine).

Skin Color

Skin color is determined by genetics, exposure, and pigment production.

• Main Pigments: Melanin, carotene, hemoglobin.

• Cyanosis: Low oxygen levels cause bluish skin.

• Jaundice: High bilirubin causes yellow skin.

• Other Factors: Blood vessels, sun exposure, melanocyte activity.

Tattoos and Burns

Tattoos are permanent because ink is deposited in the dermis. Burns are classified by depth and severity.

• Burn Degrees:

  • 1st Degree: Epidermis only.

  • 2nd Degree: Epidermis and part of dermis.

  • 3rd Degree: All layers; may affect underlying tissues.

• Burn Severity: Higher degree burns affect homeostasis and healing.

Skin Cancer

Skin cancer arises from uncontrolled cell growth in the skin.

• Main Types:

  • Basal Cell Carcinoma

  • Squamous Cell Carcinoma

  • Malignant Melanoma

• Malignant Melanoma: Most deadly; metastasizes quickly.

• ABCDE Rule: Asymmetry, Border, Color, Diameter, Evolving.

• Prevention: Sunscreen, avoiding sun exposure.

Lines and Aging

Skin lines (cleavage lines) are important for surgery; aging affects collagen and skin elasticity.

• Collagen: Provides strength; decreases with age.

• Vitamin D Production: Declines with age; skin, liver, and kidneys involved.

Summary Table: Major Tissue Types and Functions

Tissue Type	Main Function	Location Example
Epithelial	Protection, secretion, absorption	Skin, lining of GI tract, glands
Connective	Support, binding, transport	Tendons, blood, bone
Muscle	Movement	Skeletal muscles, heart, walls of organs
Nervous	Communication	Brain, spinal cord, nerves

Key Equations and Terms

• Homeostasis: The maintenance of a stable internal environment.

• Vitamin D Synthesis: $\text{UV light} + 7\text{-dehydrocholesterol} \rightarrow \text{Vitamin D}_3$

• ABCDE Rule for Melanoma: Asymmetry, Border, Color, Diameter, Evolving.

Additional info: Academic context and definitions have been expanded for clarity and completeness. All major points from the original notes have been included and organized for exam preparation.