Anatomy & Physiology: Introduction and Chemistry of Life Study Notes

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: Atom to Organism

The human body is organized in a hierarchical manner from the simplest to the most complex level.

• Levels of Organization:

  1. Atoms

  2. Molecules

  3. Organelles

  4. Cells

  5. Tissues

  6. Organs

  7. Organ Systems

  8. Organism

Anatomical Position and Directional Terms

Standard anatomical position is used as a reference point for describing locations and directions on the body.

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

• Directional Terms: Used to describe the location of one body part relative to another (e.g., anterior/posterior, superior/inferior, medial/lateral).

Body Planes and Cavities

Body planes are imaginary lines used to divide the body into sections, while body cavities house internal organs.

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

• Cavities: Dorsal (cranial and vertebral), ventral (thoracic and abdominopelvic).

• Abdominopelvic Regions: Nine regions used to describe locations within the abdomen and pelvis.

Homeostasis and Feedback Loops

Homeostasis is maintained through feedback mechanisms that regulate internal conditions.

• Negative Feedback: A process that reverses a change to keep a variable within a normal range (e.g., body temperature regulation).

• Positive Feedback: A process that amplifies a change (e.g., blood clotting, childbirth).

• Components of Feedback Loops: Stimulus, receptor, control center, effector.

Example: In temperature regulation, the stimulus is a change in body temperature, the receptor detects the change, the control center (hypothalamus) processes the information, and the effector (sweat glands or muscles) acts to restore normal temperature.

Chapter 2: Chemistry of Life

Atoms and Subatomic Particles

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

• Subatomic Particles: Protons (positive charge), neutrons (neutral), electrons (negative charge).

• Atomic Number: Number of protons in the nucleus.

• Mass Number: Sum of protons and neutrons.

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

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

Electron Shells and Chemical Bonding

Electrons are arranged in shells around the nucleus, and their arrangement determines how atoms bond.

• Electron Shells: First shell holds up to 2 electrons, second and third shells hold up to 8 electrons each.

• Octet Rule: Atoms tend to gain, lose, or share electrons to achieve a full outer shell (usually 8 electrons).

• Types of 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 polar molecules (e.g., between water molecules).

Major Elements in the Human Body

The human body is primarily composed of a few key elements.

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

Chemical Reactions

Chemical reactions involve the making or breaking of chemical bonds.

• Types of Reactions:

  • Endergonic: Absorb energy.

  • Exergonic: Release energy.

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

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

  • Exchange: Atoms are exchanged between molecules.

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

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

• Catalysts: Substances (often enzymes) that speed up reactions by lowering activation energy.

Organic Compounds

Organic compounds are molecules that contain carbon and are essential to life.

• Main Types:

  • Carbohydrates: Sugars and starches; provide energy.

  • Lipids: Fats and oils; store energy and make up cell membranes.

  • Proteins: Made of amino acids; perform a variety of functions including catalysis (enzymes), structure, and transport.

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

Polymers and Monomers

Many organic molecules are polymers, made by joining smaller units called monomers.

• Polymer: Large molecule made of repeating subunits (monomers).

• Monomer: Small molecule that can join with others to form a polymer.

• Example: Proteins are polymers of amino acids; starch is a polymer of glucose.

Saturated vs. Unsaturated Fatty Acids

Fatty acids can be classified based on the presence of double bonds.

• Saturated Fatty Acids: No double bonds; 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

Proteins have four levels of structure that determine their function.

• Primary Structure: Sequence of amino acids.

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

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

• Quaternary Structure: Association of multiple polypeptide chains.

ATP and Nucleotides

ATP (adenosine triphosphate) is the primary energy carrier in cells, and nucleotides are its building blocks.

• ATP: Stores and releases energy for cellular processes.

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

• Relationship: ATP is a nucleotide with three phosphate groups; nucleotides are also found in DNA and RNA.

Key Table: Types of Chemical Bonds

The following table summarizes the main types of chemical bonds found in biological molecules:

Bond Type	Description	Example
Ionic	Transfer of electrons from one atom to another	NaCl (table salt)
Covalent	Sharing of electron pairs between atoms	H2O (water)
Hydrogen	Weak attraction between polar molecules	Between water molecules

Key Equations

• Atomic Mass Calculation: $\text{Atomic Mass} = \text{Number of Protons} + \text{Number of Neutrons}$

• ATP Hydrolysis: $\text{ATP} + \text{H}_2\text{O} \rightarrow \text{ADP} + \text{P}_i + \text{Energy}$

Additional info: Some explanations and examples have been expanded for clarity and completeness based on standard Anatomy & Physiology curriculum.