Homeostasis and Anatomical Organization

Homeostasis: Negative vs. Positive Feedback

Homeostasis refers to the body's ability to maintain a stable internal environment despite changes in external conditions. Feedback mechanisms are essential for this regulation.

• Negative Feedback: A process that reverses a change to keep a variable within a set range. Most homeostatic mechanisms use negative feedback (e.g., body temperature regulation).

• Positive Feedback: A process that amplifies a change, moving the system further from its starting state (e.g., blood clotting, childbirth).

• Three Components of Feedback Loop:

  1. Receptor: Detects changes in the environment.

  2. Control Center: Processes information and determines response.

  3. Effector: Carries out the response to restore balance.

Anatomical Position and Directional Terms

Understanding anatomical position and directional terms is crucial for describing locations and relationships in the body.

• Anatomical Position: Standing upright, facing forward, arms at sides, palms facing forward.

• Directional Terms: Used to describe locations (e.g., superior, inferior, anterior, posterior, medial, lateral).

• Body Planes: Imaginary lines dividing the body (sagittal, frontal/coronal, transverse).

Body Regions, Cavities, and Membranes

The body is divided into regions and cavities, each with specific membranes and contents.

• Body Cavities: Spaces within the body that house organs (e.g., thoracic, abdominal, pelvic).

• Membranes: Visceral membranes cover organs; parietal membranes line cavity walls.

• Abdominopelvic Regions and Quadrants: Used to locate organs and describe pain or injury.

Chemistry in Anatomy & Physiology

pH, Acids, Bases, and Buffers

Chemical principles are foundational for understanding physiological processes.

• pH: Measures acidity or alkalinity. Defined as .

• Acid: Substance that donates hydrogen ions ().

• Base: Substance that accepts hydrogen ions.

• Buffer: Solution that resists changes in pH by neutralizing added acids or bases.

Solutions, Colloids, and Mixtures

Understanding the differences between types of mixtures is important for physiology.

• Solution: Homogeneous mixture of solute dissolved in solvent.

• Colloid: Mixture with larger particles that do not settle (e.g., cytoplasm).

• Mixture: Combination of substances not chemically bonded.

Chemical Bonds and Electron Behavior

Atoms interact through chemical bonds, which determine molecular structure and function.

• Ionic Bond: Transfer of electrons between atoms, forming charged ions.

• Covalent Bond: Sharing of electron pairs between atoms.

• Polar Covalent Bond: Unequal sharing of electrons, creating partial charges.

• Nonpolar Covalent Bond: Equal sharing of electrons.

• Hydrogen Bond: Weak attraction between a hydrogen atom and an electronegative atom (e.g., oxygen, nitrogen).

Redox Reactions and Electrolytes

Redox reactions involve the transfer of electrons, and electrolytes are substances that conduct electricity in solution.

• Oxidation: Loss of electrons.

• Reduction: Gain of electrons.

• Electrolyte: Substance that dissociates into ions in water, conducting electricity.

Organic Compounds and Macromolecules

Organic compounds are essential for life and include carbohydrates, lipids, proteins, and nucleic acids.

• Carbohydrates: Sugars and starches; classified as monosaccharides, disaccharides, polysaccharides.

• Lipids: Fats, oils, and steroids; important for energy storage and cell membranes.

• Proteins: Made of amino acids; function as enzymes, structural components, and more.

• Nucleic Acids: DNA and RNA; store and transmit genetic information.

• Nucleotide: Building block of nucleic acids, composed of a sugar, phosphate, and nitrogenous base.

Cell Structure and Function

Types of Gradients

Gradients drive movement of substances across membranes and within cells.

• Concentration Gradient: Difference in concentration of a substance across a space.

• Electrical Gradient: Difference in charge across a membrane.

• Electrochemical Gradient: Combined effect of concentration and electrical gradients.

Cell Theory and Cell Junctions

Cell theory is a fundamental concept in biology, and cell junctions connect cells together.

• Cell Theory: All living things are composed of cells; cells are the basic unit of life; all cells come from pre-existing cells.

• Cell Junctions: Structures that connect cells (e.g., tight junctions, desmosomes, gap junctions).

Plasma Membrane Structure and Function

The plasma membrane controls entry and exit of substances and maintains cellular integrity.

• Phospholipid Bilayer: Double layer of phospholipids forming the membrane.

• Membrane Proteins: Integral and peripheral proteins with various functions (transport, signaling, structural support).

• Transmembrane Proteins: Span the membrane and facilitate transport and communication.

• Ligand-Gated Channels: Open in response to binding of a specific molecule.

• Plasma Membrane Voltage: Electrical potential across the membrane due to ion distribution.

Cell Surface Structures

Specialized structures on the cell surface aid in movement and absorption.

• Microvilli: Increase surface area for absorption.

• Cilia: Move substances across cell surfaces.

• Flagella: Enable cell movement (e.g., sperm cells).

Osmosis, Diffusion, and Filtration

These processes are essential for movement of substances in and out of cells.

• Osmosis: Movement of water across a semipermeable membrane from low to high solute concentration.

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

• Filtration: Movement of substances through a membrane due to pressure.

• Osmolarity: Measure of solute concentration; changes affect fluid movement.

Transport Mechanisms

Cells use various mechanisms to move substances across membranes.

• Active Transport: Requires energy (ATP) to move substances against their gradient.

• Passive Transport: Does not require energy; includes diffusion and osmosis.

• Endocytosis: Cell engulfs substances into vesicles.

• Exocytosis: Cell expels substances via vesicles.

• Phagocytosis: Cell engulfs large particles or cells.

Cell Organelles and Their Functions

Organelles perform specialized functions within the cell.

• Endoplasmic Reticulum (ER): Rough ER synthesizes proteins; Smooth ER synthesizes lipids and detoxifies.

• Nucleus: Contains genetic material (DNA).

• Golgi Apparatus: Modifies, sorts, and packages proteins and lipids.

• Vesicles: Transport materials within the cell.

• Mitochondria: Produce ATP through cellular respiration.

• Peroxisomes: Break down fatty acids and detoxify harmful substances.

• Lysosomes: Digest cellular waste and foreign material.

• Cytoskeleton: Provides structural support and facilitates movement.

Genetic Information: Transcription and Translation

Cells use transcription and translation to produce proteins from genetic instructions.

• Transcription: DNA is copied into messenger RNA (mRNA) in the nucleus.

• Translation: mRNA is used to assemble amino acids into proteins at ribosomes.

• Codon: Sequence of three nucleotides in mRNA that codes for an amino acid.

• Anti-codon: Sequence of three nucleotides in tRNA that pairs with the codon in mRNA.

Example Table: Types of Chemical Bonds

Additional info: Some explanations and examples have been expanded for clarity and completeness.