Anatomy & Physiology: Introduction and Chemistry of Life – Study Guide

Chapter 1: Introduction to Anatomy & Physiology (A&P)

Characteristics of Living Things

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

• Cellular Composition: All living things are composed of one or more cells, which are the basic units of life.

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

• Growth: Increase in size and/or number of cells.

• Response to Stimuli: Ability to detect and respond to changes in the environment.

• Reproduction: Production of new organisms or new cells.

• Homeostasis: Maintenance of a stable internal environment.

Structural Organization

Biological organization in living organisms is hierarchical, from the simplest to the most complex:

• Atom → Molecule → Organelle → Cell → Tissue → Organ → Organ System → Organism

Anatomical Position and Directional Terms

Standard anatomical position is standing upright, facing forward, arms at the sides, palms facing forward.

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

• Planes of the Body: Sagittal (left/right), frontal (anterior/posterior), transverse (superior/inferior).

Body Cavities

The body contains several major cavities that house organs:

• Dorsal Cavity: Contains the cranial and vertebral cavities.

• Ventral Cavity: Contains the thoracic and abdominopelvic cavities.

• Subdivisions: Thoracic cavity (pleural and pericardial cavities), abdominopelvic cavity (abdominal and pelvic cavities).

Homeostasis and Feedback Loops

Homeostasis is maintained through feedback mechanisms:

• 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).

• Components: Stimulus, receptor, control center, effector.

Additional info: Negative feedback is the most common mechanism for maintaining homeostasis.

Chapter 2: Chemistry of Life

Atoms and Subatomic Particles

All matter is composed of atoms, which consist of subatomic particles:

• Protons: Positively charged, found in the nucleus.

• Neutrons: No charge, found in the nucleus.

• Electrons: Negatively charged, orbit the nucleus in electron shells.

Electron Shells and Chemical Bonding

Electrons occupy energy levels (shells) around the nucleus:

• First shell: Holds up to 2 electrons.

• Second and third shells: Each holds up to 8 electrons.

• Valence electrons: Electrons in the outermost shell, determine chemical reactivity.

• Octet Rule: Atoms tend to gain, lose, or share electrons to achieve 8 electrons in their valence shell.

Example: Carbon has 4 valence electrons and can form 4 covalent bonds.

Atomic Structure and Isotopes

• Atomic Number (Z): Number of protons in the nucleus.

• Mass Number (A): Number of protons plus neutrons.

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

• Ions: Atoms that have gained or lost electrons, acquiring a charge.

• pH: Measure of hydrogen ion concentration; $pH = -\log[H^+]$

• Polar vs. Nonpolar: Polar molecules have unequal sharing of electrons; nonpolar have equal sharing.

Major Elements in the Human Body

• Oxygen (O), Carbon (C), Hydrogen (H), Nitrogen (N) are the four most abundant elements.

Types of Chemical Bonds

• Ionic Bonds: Transfer of electrons from one atom to another (e.g., NaCl).

• Covalent Bonds: Sharing of electron pairs between atoms (e.g., H2O).

• Hydrogen Bonds: Weak attractions between a hydrogen atom and an electronegative atom (e.g., between water molecules).

Chemical Reactions

• Endergonic: Absorb energy (e.g., photosynthesis).

• Exergonic: Release energy (e.g., cellular respiration).

• Decomposition (Hydrolysis): Breaking down molecules into smaller units.

• Anabolic (Synthesis): Building larger molecules from smaller ones.

• Exchange: Atoms are exchanged between molecules.

• Redox Reactions: Involve transfer of electrons (oxidation and reduction).

Activation Energy and Catalysts

• Activation Energy: Minimum energy required to start a chemical reaction.

• Catalysts (Enzymes): Lower activation energy, increasing reaction rate.

Organic Compounds in the Body

Four main classes of organic molecules are essential for life:

• Carbohydrates: Sugars and starches; provide energy.

• Lipids: Fats, oils, and steroids; energy storage and membrane structure.

• Proteins: Chains of amino acids; structural and functional roles.

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

Monomers and Polymers

• Monomer: Small building block molecule (e.g., amino acid, nucleotide).

• Polymer: Large molecule made of repeating monomers (e.g., protein, DNA).

• Dehydration Synthesis: Joins monomers by removing water.

• Hydrolysis: Breaks polymers into monomers by adding water.

Saturated vs. Unsaturated Fatty Acids

• Saturated Fatty Acids: No double bonds between carbon atoms; solid at room temperature.

• Unsaturated Fatty Acids: One or more double bonds; liquid at room temperature.

Protein Structure

• Primary: Sequence of amino acids.

• Secondary: Alpha helices and beta sheets.

• Tertiary: 3D folding of a single polypeptide.

• Quaternary: Association of multiple polypeptides.

ATP and Nucleotides

• ATP (Adenosine Triphosphate): Main energy currency of the cell.

• Nucleotides: Building blocks of nucleic acids; consist of a sugar, phosphate, and nitrogenous base.

• Relationship: ATP is a nucleotide with three phosphate groups; nucleotides are used to build DNA and RNA.