Anatomy & Physiology: Foundational Concepts, Chemistry, Cells, and Integumentary System

Chapter 1: Basic Concepts

Features of Living Organisms

Living organisms share several defining characteristics that distinguish them from non-living matter.

• Organization: Living things exhibit a complex but ordered structure.

• Metabolism: The sum of all chemical reactions in the body, including anabolism (building up) and catabolism (breaking down).

• Responsiveness: Ability to sense and respond to stimuli.

• Growth and Development: Increase in size and functional abilities.

• Reproduction: Production of new organisms or cells.

• Homeostasis: Maintenance of a stable internal environment.

• Adaptation: Evolutionary changes that enhance survival.

Conditions That Support Life

• Essential Nutrients: Substances required for energy, growth, and maintenance (e.g., water, oxygen, nutrients).

• Stable Environment: Temperature, pH, and pressure must be regulated.

Major Fluid Compartments

The body contains two main fluid compartments:

• Intracellular Fluid (ICF): Fluid within cells; contains high concentrations of K+ and low Na+.

• Extracellular Fluid (ECF): Fluid outside cells (includes plasma and interstitial fluid); contains high Na+ and low K+.

Homeostasis

Homeostasis is the process by which organisms maintain a stable internal environment despite external changes.

• Definition: The dynamic equilibrium of the internal environment.

• Example: Regulation of body temperature, blood glucose, and pH.

Homeostatic Feedback Loops

Feedback loops are mechanisms that maintain homeostasis by detecting and responding to changes.

• Negative Feedback: Reverses a change to keep a variable within a normal range (e.g., body temperature regulation).

• Positive Feedback: Enhances or amplifies a change (e.g., blood clotting, labor contractions).

Key Point: Know the difference between positive and negative feedback.

Chapter 2: Chemistry

Kinetic and Potential Energy

Energy is the capacity to do work. In biological systems, energy exists in two main forms:

• Kinetic Energy: Energy of motion (e.g., movement of molecules).

• Potential Energy: Stored energy (e.g., chemical bonds).

General & Inorganic Chemistry

• Atomic Structure: Atoms consist of protons, neutrons, and electrons. The nucleus contains protons and neutrons; electrons orbit the nucleus.

• Subatomic Particles: Protons (+), Neutrons (0), Electrons (-).

• Isotopes: Atoms of the same element with different numbers of neutrons.

Bonds

• Covalent Bonds: Atoms share electrons (e.g., H2O).

• Ionic Bonds: Atoms transfer electrons, forming ions (e.g., NaCl).

Water: Chemical Compound & Characteristics

• Polarity: Water is a polar molecule, allowing it to dissolve many substances.

• Hydrogen Bonding: Weak bonds between water molecules, important for properties like cohesion and high specific heat.

• Solvent Properties: Water is the universal solvent in biological systems.

pH (Acids vs Bases)

• pH Scale: Measures hydrogen ion concentration; ranges from 0 (acidic) to 14 (basic), with 7 being neutral.

• Acids: Release H+ ions in solution.

• Bases: Accept H+ ions or release OH-.

Buffering Mechanisms

• Carbonic Acid-Bicarbonate Buffer System: Maintains blood pH.

$\mathrm{H_2CO_3 \rightleftharpoons HCO_3^- + H^+}$

Organic Chemistry: General Characteristics of Organic Molecules

• Lipids: Energy storage, insulation, cell membranes.

• Proteins: Structure, enzymes, signaling.

• Carbohydrates: Energy source, structural components.

• Nucleic Acids: Genetic information (DNA, RNA).

Chapter 3: Cells and Membranes

Cellular Junctions

• Tight Junctions: Seal adjacent cells to prevent leakage.

• Gap Junctions: Allow communication between cells via channels.

• Desmosomes: Provide mechanical strength by anchoring cells together.

Membrane Specializations

• Microvilli: Increase surface area for absorption.

• Flagella: Enable cell movement.

• Cilia: Move substances across cell surfaces.

Membrane Transport

Transport mechanisms regulate the movement of substances across cell membranes.

• Passive Transport: Does not require energy.

  • Simple Diffusion: Movement from high to low concentration.

  • Facilitated Diffusion: Uses carrier proteins or channels.

  • Osmosis: Diffusion of water across a semipermeable membrane.

  • Osmotic Pressure, Hydrostatic Pressure, Osmolarity, Tonicity (hyper-, iso-, hypotonic solutions).

• Active Transport: Requires energy (ATP).

  • Primary Active Transport: e.g., Sodium-potassium pump.

  • Secondary Active Transport: Uses gradients established by primary transport.

  • Vesicular/Bulk Transport: Endocytosis, exocytosis.

Cell Cycle

• Interphase: G1 (growth), S (DNA synthesis), G2 (preparation for mitosis).

• Mitosis: Division of the nucleus and cytoplasm.

Cellular Death/Adaptation

• Necrosis: Unplanned cell death due to injury.

• Apoptosis: Programmed cell death.

• Autophagy: Self-digestion of cell components.

Chapter 5: Integumentary System

Anatomy of the Skin

• Epidermis: Outermost layer, provides barrier and protection.

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

• Hypodermis: Deepest layer, composed of fat and connective tissue.

Appendages of the Skin

• Glands: Sebaceous (oil), sudoriferous (sweat), ceruminous (earwax), apocrine (scent).

• Hair and Nails: Keratinized structures for protection and sensation.

Physiological Functions

• Vitamin D Synthesis: Skin synthesizes vitamin D when exposed to UV light, which is then activated in the liver and kidneys.

• Inflammation: Response to injury or infection.

• Physical Protection: Keratin, lipid barrier, and junctions in the epidermis; fibers in the dermis.

• Thermoregulation: Regulation of body temperature via sweat and blood flow.

Wound Response and Healing

• Inflammatory Response: Involves signs such as redness, heat, swelling, and pain; mast cells play a key role.

• Superficial Wound Repair: Involves regeneration of the epidermis.

• Deep Wound Repair: Involves repair of dermal and subdermal tissues.

Burns

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

• Degrees of Burns: First (epidermis), second (epidermis and part of dermis), third (full thickness).

Skin Tumors

• Basal Cell Carcinoma: Most common, least dangerous.

• Squamous Cell Carcinoma: Can metastasize if not treated.

• Melanoma: Most dangerous, arises from melanocytes.

Additional info: Some diagrams and images referenced in the original notes are not included here, but their content has been described and expanded upon for clarity.