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: Ability to adjust to environmental changes over time.

Essential Nutrients and Conditions for Life

• Essential Nutrients: Substances required for survival, such as water, oxygen, nutrients (carbohydrates, lipids, proteins, vitamins, minerals).

• Major Fluid Compartments: The body is divided into intracellular (inside cells) and extracellular (outside cells) fluid compartments. Potassium (K+) is most abundant intracellularly, while Sodium (Na+) is most abundant extracellularly.

Homeostasis

Homeostasis is the process by which the body maintains a stable internal environment despite external changes.

• Homeostatic Feedback Loops: Mechanisms that detect changes and initiate responses to restore balance. Includes negative feedback (most common, reverses a change) and positive feedback (amplifies a change).

Example: Regulation of body temperature via sweating or shivering.

Homeostatic Control Mechanisms

• Receptor: Detects changes in the environment (stimuli).

• Control Center: Processes information and determines response (often the brain).

• Effector: Carries out the response (e.g., muscles, glands).

Positive vs. Negative Feedback: Negative feedback opposes change; positive feedback enhances it.

Chapter 2: Chemistry

Kinetic and Potential Energy

• 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. Atomic number = number of protons.

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

• Bonds:

  • Covalent Bonds: Atoms share electrons.

  • Ionic Bonds: Atoms transfer electrons, forming ions.

• Water: A polar molecule, excellent solvent, high heat capacity, involved in hydrogen bonding.

Hydrogen Bonding

• Weak attractions between the hydrogen atom of one molecule and an electronegative atom (like oxygen) of another molecule.

• Responsible for water's unique properties.

pH (Acids vs. Bases)

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

• Acids: Release H+ ions in solution.

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

Carbonic Acid-Bicarbonate Buffering Mechanism

• Maintains blood pH by reversible reaction:

$H_2CO_3 \rightleftharpoons HCO_3^- + H^+$

Organic Chemistry: General Characteristics of Organic Molecules

• Lipids: Energy storage, insulation, cell membranes.

• Proteins: Structure, enzymes, signaling.

• Carbohydrates: Energy source, structural roles.

• Nucleic Acids: DNA and RNA, genetic information storage and transfer.

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

• Passive Transport: No energy required.

  • Simple Diffusion: Movement of molecules from high to low concentration.

  • Facilitated Diffusion: Movement via transport proteins.

  • Osmosis: Diffusion of water across a semipermeable membrane.

  • Osmotic Pressure: Pressure required to stop osmosis.

  • Hydrostatic Pressure: Pressure exerted by a fluid.

  • Osmolarity: Concentration of solute particles.

  • Tonicity: Effect of solution on cell volume (hypertonic, isotonic, hypotonic).

• Active Transport: Requires energy (ATP).

  • Primary Active Transport: Direct use of ATP (e.g., sodium/potassium pump).

  • Secondary Active Transport: Uses energy from ion gradients.

  • Vesicular/Bulk Transport: Movement of large particles via endocytosis/exocytosis.

Chapter 4: Genetics and Cell Cycle

DNA, RNA, and Protein Synthesis

• Transcription: DNA is copied into mRNA.

• Translation: mRNA is used to synthesize proteins.

Cell Cycle

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

• Mitosis: Division of the nucleus and cytoplasm to form two identical daughter cells.

Cellular Death/Adaptation

• Necrosis: Unplanned cell death due to injury.

• Apoptosis: Programmed cell death, normal in development and homeostasis.

• Autophagy: Cell digests its own components for recycling.

Chapter 5: Integumentary System

Anatomy of the Skin

• Epidermis: Outermost layer, provides barrier and protection.

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

• Hypodermis: Deepest layer, mainly adipose tissue for insulation and energy storage.

Functions of the Integumentary System

• Protection: Physical barrier (keratin, lipids), immune defense (mast cells, WBCs).

• Thermoregulation: Heat loss via sweat, blood flow regulation.

• Vitamin D Synthesis: Skin initiates synthesis when exposed to UV light.

• Sensory Reception: Nerve endings detect touch, pain, temperature.

Appendages of the Skin

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

• Hair and Nails: Protection, sensation, minor roles in thermoregulation.

Wound Response and Healing

• Inflammatory Response: Mast cells release histamine, attracting WBCs.

• Superficial Wound Repair: Regeneration of epidermis.

• Deep Wound Repair: Involves dermis, may result in scar formation.

Burns

• Degrees:

  • First Degree: Epidermis only (redness, pain).

  • Second Degree: Epidermis and part of dermis (blisters).

  • Third Degree: Full thickness (epidermis, dermis, possibly deeper tissues; may be painless due to nerve damage).

• Rule of Nines: Method to estimate body surface area affected by burns.

Skin Tumors

• Basal Cell Carcinoma: Most common, least dangerous.

• Squamous Cell Carcinoma: May metastasize.

• Melanoma: Most dangerous, arises from melanocytes.

Table: Comparison of Skin Layers

Layer	Main Components	Functions
Epidermis	Keratinocytes, melanocytes	Barrier, UV protection
Dermis	Connective tissue, blood vessels, nerves	Support, sensation, thermoregulation
Hypodermis	Adipose tissue	Insulation, energy storage

Additional info: Some details, such as the full list of essential nutrients and the complete process of vitamin D synthesis, were inferred and expanded for academic completeness.