1. Organ Systems and Homeostasis

Functions and Classification of Organ Systems

The human body is organized into organ systems, each with specific functions essential for survival and homeostasis. Understanding which organs belong to each system and their overlapping roles is fundamental in Anatomy & Physiology.

• Organ Systems: Groups of organs working together to perform complex functions (e.g., digestive, respiratory, circulatory).

• Overlapping Organs: Some organs serve multiple systems (e.g., pancreas in digestive and endocrine systems; thymus in immune and endocrine systems).

• Homeostasis: The maintenance of a stable internal environment despite external changes.

Example: The heart is part of the circulatory system, while bone marrow is involved in both the skeletal and immune systems.

Feedback Mechanisms

Feedback mechanisms regulate physiological processes to maintain homeostasis.

• Positive Feedback: Enhances or amplifies changes; moves a system away from equilibrium (e.g., blood clotting).

• Negative Feedback: Counteracts changes; maintains stability (e.g., regulation of blood glucose levels).

• Stimulus: Any change in the environment that elicits a response from the body.

Example: In temperature regulation, negative feedback reduces body temperature when it rises above normal.

Basic Chemistry for Anatomy & Physiology

Key Terms and Definitions

Understanding basic chemistry is essential for studying biological processes.

• Ion: An atom or molecule with a net electric charge due to loss or gain of electrons.

• Cation: Positively charged ion.

• Anion: Negatively charged ion.

• Electrolyte: Substance that produces ions in solution and conducts electricity.

• Salt: Compound formed from the reaction of an acid and a base.

• Atomic Number: Number of protons in an atom's nucleus.

• Atomic Weight: Average mass of atoms of an element.

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

• Polar Molecule: Molecule with unequal distribution of charges.

• Non-polar Molecule: Molecule with equal sharing of electrons and no charge separation.

Chemical Bonds

Chemical bonds hold atoms together in molecules and compounds.

• Ionic Bond: Transfer of electrons from one atom to another, forming ions.

• Covalent Bond: Sharing of electron pairs between atoms.

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

Example: Water (H2O) molecules are held together by hydrogen bonds.

Acids, Bases, and Buffers

Acids and bases are important in maintaining pH balance in the body.

• Acid: Substance that releases hydrogen ions (H+) in solution.

• Base: Substance that accepts hydrogen ions or releases hydroxide ions (OH-).

• Buffer: Solution that resists changes in pH when acids or bases are added.

• pH: Measure of hydrogen ion concentration; scale ranges from 0 (acidic) to 14 (basic).

Example: Buffer system:

Acid Strength and Examples

• Strong Acid: Completely dissociates in solution (e.g., hydrochloric acid, ).

• Weak Acid: Partially dissociates (e.g., acetic acid, ).

Reduction and Oxidation

Redox reactions involve the transfer of electrons between molecules.

• Reduction: Gain of electrons.

• Oxidation: Loss of electrons.

Molecular and Structural Formulas

• Molecular Formula: Shows the number and type of atoms (e.g., ).

• Structural Formula: Shows the arrangement of atoms within the molecule.

Example: consists of two hydrogen atoms and one oxygen atom.

Biomolecules and Chemical Reactions

Dehydration vs. Hydrolysis

• Dehydration Synthesis: Formation of larger molecules by removing water.

• Hydrolysis: Breakdown of molecules by adding water.

Monomers of Biomolecules

• Carbohydrates: Monomer is monosaccharide (e.g., glucose).

• Proteins: Monomer is amino acid.

• Lipids: Monomers are fatty acids and glycerol.

• Nucleic Acids: Monomer is nucleotide.

Saturated vs. Unsaturated Lipids

• Saturated: No double bonds between carbon atoms; solid at room temperature (e.g., butter).

• Unsaturated: One or more double bonds; liquid at room temperature (e.g., olive oil).

Enzymes and Reaction Rates

• Enzyme: Biological catalyst that speeds up chemical reactions.

• Denaturation: Loss of enzyme structure and function due to environmental changes (e.g., temperature, pH).

• Temperature Effect: High temperatures can denature enzymes; optimal temperature increases reaction rate.

Factors Increasing Reaction Rate: Higher temperature, increased enzyme concentration, substrate concentration, and optimal pH.

Protein Structure

• Primary Structure: Sequence of amino acids.

• Secondary Structure: Folding into alpha-helices and beta-sheets.

• Tertiary Structure: Three-dimensional shape of a single polypeptide.

• Quaternary Structure: Association of multiple polypeptide chains.

Cell Structure and Function

Organelles and Their Functions

• Nucleus: Contains genetic material (DNA).

• Mitochondria: Site of ATP production.

• Ribosomes: Protein synthesis.

• Endoplasmic Reticulum: Protein and lipid synthesis.

• Golgi Apparatus: Modifies and packages proteins.

Transcription and Translation

• Transcription: DNA is copied into mRNA.

• Translation: mRNA is used to synthesize proteins.

• Components: mRNA, tRNA, ribosomes, introns, exons.

Cell Division: Mitosis and Interphase

• Purpose of Mitosis: Cell division for growth and repair.

• Stages of Mitosis (PMAT):

  • Prophase

  • Metaphase

  • Anaphase

  • Telophase

• Interphase: Cell grows and DNA replicates.

Cell Membrane and Transport

• Passive Transport: Movement of substances without energy (e.g., diffusion, osmosis).

• Hypertonic Solution: Higher solute concentration outside the cell; cell shrinks.

• Hypotonic Solution: Lower solute concentration outside; cell swells.

• Isotonic Solution: Equal solute concentration; no net movement.

• Crenation: Shrinking of cells in hypertonic solution.

• Lysis: Bursting of cells in hypotonic solution.

• Endocytosis: Uptake of materials by the cell (phagocytosis, pinocytosis).

• Sodium-Potassium Pump: Active transport mechanism maintaining cell potential.

Cell Membrane Components

• Phospholipid Bilayer: Main structure of cell membrane.

• Membrane Proteins: Functions include transport, signaling, and structural support.

DNA, Genes, and Chromosomes

• DNA: Genetic material; stores instructions for protein synthesis.

• Monomer of DNA: Nucleotide (composed of sugar, phosphate, and nitrogenous base).

• Gene: Segment of DNA coding for a specific protein.

• Chromosome: Structure containing DNA and associated proteins.

Tissues and Examples

Tissue Types

• Connective Tissue: Supports and binds other tissues (e.g., tendons, ligaments).

• Epithelial Tissue: Covers body surfaces and lines cavities.

• Muscle Tissue: Responsible for movement.

• Nervous Tissue: Transmits electrical signals.

Example: Tendons and ligaments are composed of dense connective tissue.

Specialized Structures

• Microvilli: Increase surface area for absorption; found in intestines.

• Cilia: Move substances across cell surfaces; found in respiratory tract.

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