Tissues and Integumentary System: Study Guide

Tissues and Integumentary System

Overview

This study guide covers the major topics related to tissues and the integumentary system, focusing on terminology, classification, structure, and function. It is designed for college-level Anatomy & Physiology students.

Histology: The Study of Tissues

Main Tissue Types

There are four major types of tissues in the human body. Each type has distinct characteristics, functions, and locations.

• Epithelial Tissue: Covers body surfaces, lines cavities, and forms glands.

• Connective Tissue: Supports, binds, and protects organs.

• Muscle Tissue: Responsible for movement.

• Nervous Tissue: Conducts electrical impulses and processes information.

Any organ may contain a mix of these tissue types.

Epithelial Tissue

• Specific Types: There are 5 specific types of epithelial tissue, classified by cell shape and number of layers.

• Functions: Protection, absorption, secretion, and sensation.

• Locations: Found lining surfaces and cavities throughout the body.

• Polarity: Has an apical (top) and basal (bottom) surface; the basement membrane anchors the tissue.

• Glandular Epithelium: Forms glands; secretion can be merocrine, apocrine, or holocrine.

Example: Simple squamous epithelium lines blood vessels and allows for rapid diffusion.

Connective Tissue

• Specific Types: There are 7 specific types, including loose, dense, cartilage, bone, blood, adipose, and reticular.

• Functions: Support, protection, transport, insulation, and storage.

• Structural Elements: Cells, fibers (collagen, elastic, reticular), and ground substance.

Example: Adipose tissue stores energy and insulates the body.

Muscle Tissue

• Specific Types: There are 3 types—skeletal, cardiac, and smooth muscle.

• Functions: Movement, posture, and heat production.

• Locations: Skeletal muscles attach to bones; cardiac muscle forms the heart; smooth muscle lines organs.

Example: Cardiac muscle contracts to pump blood throughout the body.

Nervous Tissue

• Specific Types: There are 2 types of cells—neurons and neuroglia.

• Functions: Neurons transmit electrical signals; neuroglia support and protect neurons.

Example: Neurons in the brain process sensory information.

Tissue Repair and Health

• Repair Factors: Nutrition, blood supply, and cell type affect tissue repair.

• Function Loss: Damage to specific tissue types can impair organ function.

Integumentary System

Functions of the Integumentary System

• Protection against physical, chemical, and biological harm

• Regulation of body temperature

• Sensation (touch, pain, temperature)

• Excretion of wastes

• Synthesis of vitamin D

Main Regions/Layers of the Integument

• Epidermis: Outermost layer; avascular; main tissue is epithelial.

• Dermis: Middle layer; contains connective tissue, blood vessels, nerves.

• Hypodermis: Deepest layer; mainly adipose tissue; anchors skin to underlying structures.

Epidermis: Structure and Function

• Cell Types: Keratinocytes (produce keratin), melanocytes (produce melanin), dendritic cells (immune function), Merkel cells (sensory function).

• Layers: Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum (only in thick skin), stratum corneum.

• Function: Provides barrier, prevents water loss, and protects against pathogens.

Dermis: Structure and Function

• Layers: Papillary (loose connective tissue, dermal papillae), reticular (dense irregular connective tissue).

• Functions: Provides strength, elasticity, and houses blood vessels, nerves, and accessory structures.

Hypodermis

• Main Tissue: Adipose tissue.

• Function: Insulation, energy storage, and cushioning.

Accessory Structures of the Skin

• Hair: Protects, insulates, and senses.

• Nails: Protects fingertips, aids in grasping.

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

Skin Color

• Melanocytes: Produce melanin, which determines skin color.

• Variation: Skin color varies due to genetic differences in melanin production and distribution.

Tattoos and Burns

• Tattoo: Ink is placed in the dermis, which is stable and not shed like the epidermis.

• Burns: Classified by depth (first, second, third degree); deeper burns affect homeostasis and healing.

Skin Cancer

• Main Types: Basal cell carcinoma, squamous cell carcinoma, melanoma.

• ABCDE Rule: Asymmetry, Border, Color, Diameter, Evolving—used to identify melanoma.

Cleavage Lines

• Natural orientation of collagen fibers in the dermis; important for surgical incisions.

Age and Skin

• Collagen: Decreases with age, leading to wrinkles.

• Prevention: Sun protection, hydration, and nutrition help maintain skin health.

Vitamin D Synthesis

• Skin synthesizes vitamin D when exposed to UV light.

• Vitamin D is important for calcium absorption and bone health.

• Other organs involved: Liver and kidneys (convert vitamin D to active form).

Summary Table: Major Tissue Types

Tissue Type	Main Function	Location	Key Cell Types
Epithelial	Protection, secretion, absorption	Body surfaces, cavities, glands	Keratinocytes, melanocytes, glandular cells
Connective	Support, binding, transport	Bones, blood, cartilage, fat	Fibroblasts, adipocytes, chondrocytes
Muscle	Movement	Skeletal muscles, heart, organs	Muscle fibers (skeletal, cardiac, smooth)
Nervous	Communication, control	Brain, spinal cord, nerves	Neurons, neuroglia

Key Equations

• Vitamin D Synthesis:

$\text{7-dehydrocholesterol} + \text{UV light} \rightarrow \text{cholecalciferol (vitamin D}_3\text{)}$

Additional info: Some details, such as the specific names of cell types and layers, were inferred from standard Anatomy & Physiology curriculum.