Foundations of Anatomy & Physiology: Structural Organization, Chemistry, and Body Systems

Anatomy and Physiology: Introduction

Definitions and Scope

• Anatomy: The study of the structure of body parts and their relationships to one another.

• Physiology: The study of the function of the body and its parts.

• Gross (Macroscopic) Anatomy: Study of large body structures visible to the naked eye.

• Microscopic Anatomy: Study of structures too small to be seen without magnification.

  • Cytology: Study of cells.

  • Histology: Study of tissues.

Levels of Structural Organization

Hierarchy of Complexity

• Atoms: Smallest units of matter (e.g., carbon, hydrogen).

• Molecules: Combinations of atoms (e.g., water, proteins).

• Organelles: Basic components of cells (e.g., mitochondria, nucleus).

• Cells: Smallest units of living things.

• Tissues: Groups of similar cells with a common function (e.g., muscle tissue).

• Organs: Structures composed of at least two tissue types performing specific functions (e.g., heart, liver).

• Organ Systems: Groups of organs working together for a common purpose (e.g., digestive system).

• Organism: An individual living thing.

Necessary Life Functions

Basic Processes Required for Life

• Maintaining Boundaries: Separation of internal and external environments (e.g., skin, cell membrane).

• Movement: Activities promoted by the muscular system, including movement of substances within the body.

• Responsiveness (Excitability): Ability to sense and respond to stimuli (e.g., withdrawal reflex).

• Digestion: Breakdown of ingested food into absorbable molecules.

• Metabolism: All chemical reactions in the body, including catabolism (breakdown) and anabolism (synthesis).

• Excretion: Removal of wastes from the body (e.g., urine, feces, CO2).

• Reproduction: Cellular (mitosis) and organismal (offspring) reproduction.

• Growth: Increase in size of a body part or the organism as a whole.

Survival Requirements

Essential Environmental Factors

• Nutrients: Chemical substances for energy and cell building (e.g., carbohydrates, proteins, fats, vitamins, minerals).

• Oxygen: Required for oxidative reactions that release energy from food; about 20% of air is oxygen.

• Water: 50-60% of body weight; most abundant chemical in the body.

• Normal Body Temperature: Necessary for proper chemical reaction rates (approx. 37°C or 98.6°F).

• Atmospheric Pressure: Required for proper gas exchange in the lungs.

Homeostasis

Maintaining Internal Stability

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

• Components:

  • Receptor: Monitors environment and detects changes (stimuli).

  • Control Center: Determines set point and processes information.

  • Effector: Carries out the response to restore balance.

Feedback Mechanisms

• Negative Feedback: Reduces or shuts off the original stimulus (e.g., regulation of body temperature, blood glucose).

• Positive Feedback: Enhances or exaggerates the original stimulus (e.g., blood clotting, labor contractions).

Anatomical Position and Directional Terms

Standard Reference Position

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

Directional Terms

• Superior (Cranial): Toward the head/upper part of a structure.

• Inferior (Caudal): Away from the head/lower part.

• Anterior (Ventral): Toward the front.

• Posterior (Dorsal): Toward the back.

• Medial: Toward the midline.

• Lateral: Away from the midline.

• Proximal: Closer to the origin of a body part or point of attachment.

• Distal: Farther from the origin or point of attachment.

• Superficial (External): Toward or at the body surface.

• Deep (Internal): Away from the body surface; more internal.

Regional Terms

• Axial: Head, neck, trunk.

• Appendicular: Limbs (arms and legs).

Body Planes and Sections

• Sagittal Plane: Divides body into right and left parts.

• Frontal (Coronal) Plane: Divides body into anterior and posterior parts.

• Transverse (Horizontal) Plane: Divides body into superior and inferior parts.

• Oblique Section: Cuts made diagonally between horizontal and vertical planes.

Body Cavities

Major Body Cavities

• Dorsal Body Cavity:

  • Cranial Cavity: Encloses the brain.

  • Vertebral (Spinal) Cavity: Encloses the spinal cord.

• Ventral Body Cavity:

  • Thoracic Cavity: Surrounded by ribs and chest muscles.

    • Pleural Cavities: Each surrounds a lung.

    • Mediastinum: Contains pericardial cavity, surrounds thoracic organs.

    • Pericardial Cavity: Encloses the heart.

  • Abdominopelvic Cavity: Contains abdominal and pelvic organs.

Body Cavity Membranes

• Serosa (Serous Membrane): Moist membrane lining ventral body cavities.

• Parietal Serosa: Lines cavity walls.

• Visceral Serosa: Covers organs within the cavity.

• Serous Fluid: Lubricates and reduces friction between membranes.

Other Body Cavities

• Oral and Digestive Cavities: Mouth, teeth, tongue.

• Nasal Cavity: Part of respiratory system.

• Orbital Cavities: Contain the eyes.

• Middle Ear Cavities: Medial to eardrums, transmit sound vibrations.

• Synovial Cavities: Joint cavities, enclosed within fibrous capsules.

Body Regions

• Head (Cephalic): Frontal, orbital, mental, buccal, occipital, nasal.

• Neck (Cervical)

• Trunk: Sternal, thoracic, mammary, axillary, abdominal, umbilical, inguinal, pelvic, pubic, scapular, vertebral, lumbar, gluteal.

• Limbs: Brachial, antebrachial, carpal, digital, femoral, crural, tarsal, pedal, etc.

Basic Chemistry for Anatomy & Physiology

Matter and Energy

• Matter: Anything that occupies space and has mass.

• Energy: Capacity to do work; exists as kinetic (movement) or potential (stored) energy.

Forms of Energy

• Chemical Energy: Stored in bonds of chemical substances.

• Electrical Energy: Movement of charged particles.

• Mechanical Energy: Directly involved in moving matter.

• Radiant (Electromagnetic) Energy: Travels in waves (e.g., light).

Conversion of Energy

• Energy can be converted from one form to another, but some is always lost as heat.

Matter: State and Composition

• Major elements: Carbon, oxygen, hydrogen, nitrogen (96% of body weight).

• Other important elements: Sodium, potassium, calcium, iron, chlorine.

Subatomic Particles

• Protons: Positive charge, mass 1 amu, in nucleus.

• Neutrons: No charge, mass 1 amu, in nucleus.

• Electrons: Negative charge, negligible mass, orbit nucleus.

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

• Radioisotopes: Unstable isotopes that emit radiation.

Mixtures and Compounds

Types of Mixtures

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

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

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

Concentration of Solutions

• Expressed as percent, molarity (moles/liter), etc.

Chemical Bonds

• Ionic Bonds: Electron transfer between atoms (e.g., NaCl).

• Covalent Bonds: Sharing of electron pairs; can be polar or nonpolar.

• Hydrogen Bonds: Weak attraction between hydrogen and electronegative atom.

Chemical Reactions

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

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

• Exchange: Both synthesis and decomposition occur.

• Reversible Reactions: Can proceed in both directions.

• Irreversible Reactions: Proceed in one direction only.

Energy Flow in Chemical Reactions

• Exergonic: Release energy.

• Endergonic: Absorb energy.

• Catalysts: Increase rate of reaction without being consumed (e.g., enzymes).

Rate of Chemical Reaction

• Increased by higher temperature, higher concentration, and presence of catalysts.

Chemical Compounds of Living Matter

Inorganic Compounds

• Water: Most abundant, excellent solvent, high heat capacity, important for chemical reactions.

• Salts: Ionic compounds that dissociate in water to form electrolytes.

Salts Commonly Found in the Body

Salt	Formula	Function
Sodium chloride	NaCl	Major extracellular ion, nerve impulse transmission
Potassium chloride	KCl	Major intracellular ion, muscle contraction
Calcium phosphate	Ca3(PO4)2	Bone structure, teeth
Magnesium chloride	MgCl2	Enzyme cofactor
Sodium bicarbonate	NaHCO3	Buffering of blood pH
Additional info: Table inferred and expanded for clarity.

Acids and Bases

• Acids: Proton donors; release H+ in solution (e.g., HCl).

• Bases: Proton acceptors; release OH- in solution (e.g., NaOH).

• pH Scale: Measures hydrogen ion concentration; 0-14 scale, 7 is neutral.

Macromolecules: Carbohydrates, Lipids, Proteins, Nucleic Acids

Carbohydrates

• Monosaccharides: Simple sugars (e.g., glucose, fructose).

• Disaccharides: Two monosaccharides joined (e.g., sucrose, lactose).

• Polysaccharides: Many monosaccharides (e.g., glycogen, starch).

• Functions: Energy source, structural component.

Lipids

• Triglycerides: Fats and oils, energy storage.

• Phospholipids: Major component of cell membranes.

• Steroids: Cholesterol, hormones.

Proteins

• Amino Acids: Building blocks of proteins.

• Levels of Structure: Primary, secondary, tertiary, quaternary.

• Functions: Enzymes, structural, transport, signaling.

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

Enzymes

• Biological catalysts that speed up chemical reactions.

• Highly specific for substrates.

Nucleic Acids

• DNA (Deoxyribonucleic Acid): Genetic material, double helix, bases A, T, C, G.

• RNA (Ribonucleic Acid): Protein synthesis, single-stranded, bases A, U, C, G.

Adenosine Triphosphate (ATP)

• Main energy currency of the cell.

• Stores and releases energy for cellular processes.