Anatomy & Physiology Study Guide: Tissues, Skin, and Skeletal System

Chapter 3: Body Tissues

Types of Body Tissues

The human body is composed of four basic tissue types, each with specialized functions and structures.

• Epithelial Tissue: Covers body surfaces, lines cavities, and forms glands. Functions include protection, absorption, filtration, excretion, secretion, and sensory reception.

• Connective Tissue: Supports, protects, and binds other tissues. Includes bone, cartilage, adipose (fat), and blood.

• Muscle Tissue: Responsible for movement. Types include skeletal (voluntary movement), cardiac (heart), and smooth (walls of hollow organs).

• Nervous Tissue: Initiates and transmits electrical impulses, coordinating body activities.

Key Point: Each tissue type has unique cells and extracellular components that determine its function.

Classification and Function of Epithelial Tissue

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

• Layers: Simple (one layer), stratified (multiple layers).

• Functions: Protection (skin), absorption (intestines), filtration (kidneys), secretion (glands).

Example: Simple squamous epithelium lines the air sacs of the lungs for efficient gas exchange.

Chapter 4: Skin and Body Membranes

Functions of the Skin

The skin, or integument, is the body's largest organ and serves multiple vital functions:

• Protection: Acts as a barrier against pathogens, chemicals, and physical injury.

• Thermoregulation: Regulates body temperature through sweat and blood flow.

• Sensation: Contains sensory receptors for touch, pain, and temperature.

• Metabolic Functions: Synthesizes vitamin D when exposed to sunlight.

• Excretion: Removes waste products through sweat.

Structure of the Skin

• Epidermis: Outermost layer, composed of stratified squamous epithelium. Provides waterproofing and protection.

• Dermis: Middle layer, contains connective tissue, blood vessels, nerves, hair follicles, and glands.

• Hypodermis (Subcutaneous Layer): Made of adipose tissue; insulates and anchors skin to underlying structures.

Skin Burns

• Types: First-degree (epidermis only), second-degree (epidermis and part of dermis), third-degree (full thickness, destroys both layers).

• Layers Damaged: Severity increases with depth of tissue involvement.

• Rule of Nines: Used to estimate the percentage of body surface area affected by burns.

Skin Cancer

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

• Melanoma: Most dangerous; arises from melanocytes.

• ABCDE Rule: Asymmetry, Border irregularity, Color variation, Diameter >6mm, Evolving shape/size.

Molecular Biology in Skin

• Transcription: DNA is copied into mRNA.

• Translation: mRNA is used to synthesize proteins.

• Gene Mutation: A change in DNA sequence can lead to skin cancer if it affects cell cycle regulation.

Chapter 5: The Skeletal System

Functions of the Skeletal System

• Support: Framework for the body.

• Protection: Shields vital organs (e.g., skull protects brain).

• Movement: Provides levers for muscles.

• Mineral Storage: Reservoir for calcium and phosphorus.

• Blood Cell Formation: Hematopoiesis in red bone marrow.

Classification of Bones

• Long Bones: Longer than wide (e.g., femur).

• Short Bones: Cube-shaped (e.g., carpals).

• Flat Bones: Thin, often curved (e.g., skull, ribs).

• Irregular Bones: Complex shapes (e.g., vertebrae).

Structure of Bone

• Diaphysis: Shaft of long bone, contains compact bone.

• Epiphyses: Ends of long bone, contain spongy bone and red marrow.

• Periosteum: Membrane covering bone surface.

• Endosteum: Lines internal bone surfaces.

Bone Remodeling and Homeostasis

• Osteoblasts: Build new bone matrix.

• Osteoclasts: Break down bone matrix.

• Calcium Homeostasis: Regulated by hormones such as parathyroid hormone (PTH) and calcitonin.

Equation:

$\text{Ca}^{2+}_{\text{blood}} \xleftrightarrow{\text{PTH/calcitonin}} \text{Ca}^{2+}_{\text{bone}}$

Axial and Appendicular Skeleton

• Axial Skeleton: Skull, vertebral column, rib cage.

• Appendicular Skeleton: Limbs and girdles (pectoral and pelvic).

• Articulations: Joints where bones meet; classified by structure and function.

Short Answer Topics

• Burn scenarios: Identify damaged tissues and their roles in healing.

• Bone remodeling and calcium homeostasis/osteoporosis.

• Skin cancer: Types, detection, and causes (including molecular biology aspects).

Table: Types of Body Tissues and Their Functions

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

Additional info: These notes expand on the study guide prompts by providing definitions, examples, and context for each major topic relevant to Anatomy & Physiology chapters on tissues, skin, and the skeletal system.