Foundations of Anatomy & Physiology: Organization, Chemistry, and Homeostasis

Chapter 1 – Organization of the Human Body

Defining Anatomy and Physiology

Anatomy is the study of the structure of body parts and their relationships to one another. Physiology is the study of the function of the body’s structural machinery. Both fields have several subdivisions:

• Gross (macroscopic) anatomy: Study of large body structures visible to the naked eye (e.g., heart, bones).

• Microscopic anatomy: Study of structures too small to be seen with the naked eye (e.g., cells, tissues).

• Developmental anatomy: Study of structural changes throughout the lifespan.

• Systemic physiology: Study of the function of specific organ systems.

Complementarity of Structure and Function

The principle of complementarity states that function always reflects structure; what a structure can do depends on its specific form. For example, bones can support and protect body organs because they contain hard mineral deposits.

Levels of Structural Organization

The human body is organized into hierarchical levels:

• Chemical level: Atoms combine to form molecules.

• Cellular level: Cells are made up of molecules.

• Tissue level: Tissues consist of similar types of cells.

• Organ level: Organs are made up of different types of tissues.

• Organ system level: Organ systems consist of different organs that work together closely.

• Organismal level: The human organism is made up of many organ systems.

Major Body Systems: Functions and Components

The body has 11 major organ systems, each with specific functions and components:

• Integumentary: Skin, hair, nails; protects body, regulates temperature.

• Skeletal: Bones, joints; supports and protects organs, stores minerals.

• Muscular: Skeletal muscles; movement, posture, heat production.

• Nervous: Brain, spinal cord, nerves; fast-acting control system.

• Endocrine: Glands (e.g., thyroid, pancreas); hormone secretion, regulation.

• Cardiovascular: Heart, blood vessels; transports blood, nutrients, gases.

• Lymphatic/Immune: Lymph nodes, spleen; defense, fluid balance.

• Respiratory: Lungs, trachea; gas exchange (O2/CO2).

• Digestive: Stomach, intestines; breakdown and absorption of food.

• Urinary: Kidneys, bladder; waste elimination, water balance.

• Reproductive: Ovaries/testes; production of offspring.

Functional Characteristics Necessary for Life

• Maintaining boundaries (e.g., skin separates internal from external environment)

• Movement (muscular system, movement of substances)

• Responsiveness (ability to sense and respond to stimuli)

• Digestion (breakdown of ingested food)

• Metabolism (all chemical reactions in the body)

• Excretion (removal of wastes)

• Reproduction (cellular and organismal levels)

• Growth (increase in size and number of cells)

Survival Needs of the Human Body

• Nutrients (carbohydrates, proteins, fats, vitamins, minerals)

• Oxygen (required for metabolic reactions)

• Water (most abundant chemical in the body)

• Normal body temperature (necessary for chemical reactions)

• Appropriate atmospheric pressure (for gas exchange in lungs)

Homeostasis and Its Importance

Homeostasis is the maintenance of a stable internal environment despite external changes. It is vital for normal body functioning and sustaining life.

Feedback Mechanisms

• Negative feedback: The response reduces or shuts off the original stimulus (e.g., regulation of body temperature, blood glucose levels).

• Positive feedback: The response enhances or exaggerates the original stimulus (e.g., blood clotting, labor contractions).

Anatomical Position and Terminology

• Anatomical position: Body erect, feet slightly apart, palms facing forward, thumbs pointing away from body.

• Directional terms: Superior/inferior, anterior/posterior, medial/lateral, proximal/distal, superficial/deep.

• Body planes: Sagittal, frontal (coronal), transverse (horizontal).

• Surface anatomy landmarks: Standardized regions and reference points on the body.

Body Cavities and Their Subdivisions

• Dorsal cavity: Cranial cavity (brain), vertebral cavity (spinal cord).

• Ventral cavity: Thoracic cavity (heart, lungs), abdominopelvic cavity (digestive organs, urinary bladder, reproductive organs).

Serous Membranes

• Pleura: Surrounds lungs.

• Pericardium: Surrounds heart.

• Peritoneum: Surrounds abdominal organs.

Abdominopelvic Regions and Quadrants

The abdominopelvic cavity is divided for clinical and anatomical reference:

• Four quadrants: Right upper, left upper, right lower, left lower.

• Nine regions: Right/left hypochondriac, epigastric, right/left lumbar, umbilical, right/left iliac (inguinal), hypogastric.

Each region contains specific organs (e.g., liver in right upper quadrant, bladder in hypogastric region).

Chapter 2 – Body Chemistry

Basic Chemical Concepts

• Chemical element: Substance that cannot be broken down by ordinary chemical means.

• Atom: Smallest unit of an element, composed of protons, neutrons, and electrons.

• Atomic number: Number of protons in an atom.

• Atomic mass: Sum of protons and neutrons.

• Atomic weight: Average mass of all isotopes of an element.

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

• Radioisotope: Isotope with an unstable nucleus that emits radiation.

• Anabolism: Synthesis of complex molecules from simpler ones (requires energy).

• Catabolism: Breakdown of complex molecules into simpler ones (releases energy).

Major Energy Forms

• Chemical energy: Stored in bonds of chemical substances.

• Electrical energy: Movement of charged particles.

• Mechanical energy: Directly involved in moving matter.

• Radiant energy: Energy that travels in waves (e.g., light, X-rays).

Elements Forming the Bulk of the Body

• Oxygen (O)

• Carbon (C)

• Hydrogen (H)

• Nitrogen (N)

Subatomic Particles

• Protons: Positive charge, in nucleus.

• Neutrons: No charge, in nucleus.

• Electrons: Negative charge, orbit nucleus.

Molecules, Compounds, and Mixtures

• Molecule: Two or more atoms bonded together.

• Compound: Two or more different atoms bonded together.

• Mixture: Two or more substances physically intermixed.

Types of mixtures:

• Solutions: Homogeneous mixtures (e.g., saline).

• Colloids: Heterogeneous, do not settle (e.g., cytosol).

• Suspensions: Heterogeneous, particles settle (e.g., blood).

Chemical Bonding and the Octet Rule

• Electrons in the outer shell (valence electrons) determine chemical bonding.

• Octet rule: Atoms are stable with 8 electrons in their valence shell.

Types of Chemical Bonds

• Ionic bonds: Transfer of electrons (e.g., NaCl).

• Covalent bonds: Sharing of electrons (e.g., H2O).

• Hydrogen bonds: Weak attractions between polar molecules.

Polar vs. Nonpolar Compounds

• Nonpolar: Electrons shared equally (e.g., O2).

• Polar: Electrons shared unequally, creating partial charges (e.g., H2O).

Chemical Reactions

• Synthesis (anabolic): A + B → AB

• Decomposition (catabolic): AB → A + B

• Exchange: AB + C → AC + B

Oxidation-Reduction (Redox) Reactions

• Involve transfer of electrons between atoms/molecules.

• Oxidation: Loss of electrons.

• Reduction: Gain of electrons.

Factors Affecting Reaction Rates

• Temperature (higher = faster)

• Concentration (higher = faster)

• Particle size (smaller = faster)

• Catalysts (e.g., enzymes) speed up reactions

Importance of Water and Salts

• Water: Universal solvent, high heat capacity, involved in chemical reactions.

• Salts: Ionic compounds, dissociate in water, important for nerve and muscle function.

Acids, Bases, and pH

• Acid: Releases H+ ions in solution.

• Base: Accepts H+ ions or releases OH-.

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

Dehydration Synthesis and Hydrolysis

• Dehydration synthesis: Removal of water to form bonds.

• Hydrolysis: Addition of water to break bonds.

Biological Macromolecules

• Carbohydrates: Sugars and starches; energy source; building blocks are monosaccharides.

• Lipids: Fats, oils, steroids; energy storage, insulation; building blocks are fatty acids and glycerol.

• Proteins: Structural, enzymatic, regulatory roles; building blocks are amino acids.

• Nucleic acids: DNA and RNA; genetic information; building blocks are nucleotides.

Protein Structure and Denaturation

• Primary: Sequence of amino acids.

• Secondary: Alpha helices and beta sheets.

• Tertiary: 3D folding of polypeptide.

• Quaternary: Association of multiple polypeptides.

• Denaturation: Loss of structure and function due to environmental changes.

Enzyme Function

• Enzymes are biological catalysts that speed up reactions by lowering activation energy.

• They are specific to substrates and are not consumed in the reaction.

DNA vs. RNA

• DNA: Double-stranded, deoxyribose sugar, stores genetic information.

• RNA: Single-stranded, ribose sugar, involved in protein synthesis.

ATP: Structure and Function

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

• Structure: Adenine base, ribose sugar, three phosphate groups.

• Function: Releases energy when phosphate bonds are broken: $ATP \rightarrow ADP + P_i + \text{energy}$