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).

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

Body Cavities

Body cavities protect organs and allow for changes in size and shape.

• 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 by feedback mechanisms that regulate internal conditions.

• 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 of Feedback Loops: 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

Electron shells are energy levels where electrons reside. The arrangement of electrons determines how atoms bond.

• 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 and bonding.

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

Types of Chemical Bonds

• Ionic Bonds: Transfer of electrons from one atom to another, resulting in charged ions (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).

Major Elements in the Human Body

• Major Elements: Oxygen (O), Carbon (C), Hydrogen (H), Nitrogen (N), Calcium (Ca), Phosphorus (P).

• These elements make up over 98% of the human body by mass.

Definitions and Properties

• Atomic Number: Number of protons in the nucleus.

• Atomic Mass: Sum of protons and neutrons.

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

• Ion: Atom or molecule with a net electric charge.

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

• Molar: Relating to the concentration of a solution, measured in moles per liter (mol/L).

Chemical Reactions

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

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

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

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

• Exchange Reactions: Involve both synthesis and decomposition.

• Redox Reactions: Involve transfer of electrons between atoms.

Activation Energy and Catalysts

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

• Catalysts (Enzymes): Substances that speed up chemical reactions by lowering activation energy.

Organic Compounds in the Body

The four main classes of organic compounds are:

• Carbohydrates: Sugars and starches; provide energy.

• Lipids: Fats and oils; store energy, form cell membranes.

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

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

Polymers and Monomers

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

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

• 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 (e.g., butter).

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

Protein Structure

• Primary Structure: Sequence of amino acids.

• Secondary Structure: Local folding (alpha helices, beta sheets).

• Tertiary Structure: 3D shape of a single polypeptide.

• Quaternary Structure: 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 group, and nitrogenous base.

• ATP is a nucleotide with three phosphate groups; hydrolysis of ATP releases energy for cellular processes.

Example: The hydrolysis of ATP to ADP and inorganic phosphate releases energy: $\mathrm{ATP} + \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{ADP} + \mathrm{P}_i + \text{energy}$

Additional info: Understanding the relationship between ATP and nucleotides is essential for grasping cellular energy transfer.