Chapter 1: Introduction to Human Anatomy and Physiology

Anatomy vs. Physiology

Anatomy and physiology are closely related disciplines that form the foundation of medical science. Anatomy focuses on the structure of body parts, while physiology studies their function.

• Anatomy: Study of structure (forms and organization of body parts). Example: Shape of mouth allows food intake.

• Physiology: Study of function (how body parts work). Example: Heart muscle pumps blood.

• Connection: Structure enables function; form and function are inseparable.

Levels of Structural Organization

The human body is organized into hierarchical levels, each with increasing complexity.

• Atoms: Smallest unit of matter (e.g., Li).

• Molecules: Water, glucose.

• Macromolecules: Proteins, DNA.

• Organelles: Mitochondria, nuclei.

• Cells: Muscle cell, nerve cell.

• Tissues: Squamous epithelium, connective tissue.

• Organs: Skin, heart, kidney.

• Organ systems: Skeletal, digestive, cardiovascular.

• Organism: Human body.

Characteristics of Life

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

• Movement: Body part or organ motion.

• Responsiveness: Reaction to change.

• Growth: Increase in size.

• Reproduction: Creation of new organisms.

• Respiration: O2 in, CO2 out, energy release.

• Digestion: Breakdown of food.

• Absorption: Movement through membranes.

• Circulation: Transport of fluids.

• Assimilation: Changing absorbed substances.

• Excretion: Removal of wastes.

• Metabolism: Sum of all chemical reactions.

Requirements of Organisms

Organisms require certain environmental factors to survive and function.

• Water: Most abundant, regulates temperature, medium for reactions, transport.

• Food: Energy and raw materials.

• Oxygen: Releases energy from nutrients.

• Heat: Regulates reaction rates.

• Pressure: Atmospheric (breathing), hydrostatic (blood pressure).

Homeostasis

Homeostasis is the maintenance of a stable internal environment, essential for survival.

• Definition: Maintaining a stable internal environment.

• Components:

  1. Receptor: Detects changes (stimuli).

  2. Control Center: Decides set point (e.g., brain).

  3. Effector: Responds to restore balance.

• Negative Feedback: Corrects deviations from set point (e.g., sweating, shivering).

Organization of the Human Body

The human body is organized into cavities, membranes, and organ systems, each with specific functions.

Body Cavities

• Axial: Head, neck, trunk.

• Cranial cavity: Brain.

• Vertebral canal: Spinal cord.

• Thoracic cavity: Lungs, heart, trachea, esophagus.

• Abdominopelvic cavity:

  • Abdominal: Stomach, liver, spleen, intestines.

  • Pelvic: Bladder, reproductive organs.

• Appendicular: Upper and lower limbs.

Serous Membranes

• Pleura: Lungs (visceral = covers lung; parietal = lines cavity).

• Pericardium: Heart.

• Peritoneum: Abdominal organs.

Organ Systems (11 total)

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

• Skeletal: Bones, ligaments; supports, protects, produces blood cells.

• Muscular: Muscles; movement, posture, heat.

• Nervous: Brain, spinal cord, nerves; rapid communication.

• Endocrine: Glands; hormones regulate metabolism.

• Cardiovascular: Heart, vessels; transport nutrients, gases, wastes.

• Lymphatic: Lymph nodes, spleen; immunity, fluid balance.

• Digestive: Stomach, intestines, liver; breakdown food, absorb nutrients.

• Respiratory: Lungs, trachea; gas exchange.

• Urinary: Kidneys, bladder; remove wastes, balance fluids.

• Reproductive: Testes/ovaries; produce offspring.

Life Span Changes

Human bodies undergo predictable changes as they age.

• 30s: Minor joint stiffness, reduced fertility, gray hair.

• 40s-60s: Wrinkles, higher blood pressure, increased blood glucose.

• 60s: Deep wrinkles, weaker immune system.

• Aging: Loss of collagen, elastin, fat; slower metabolism; possible Alzheimer's (beta-amyloid buildup).

Anatomical Terminology

Standardized terms describe positions, planes, and regions of the body.

Positions

• Superior / Inferior: Above/below.

• Anterior (ventral) / Posterior (dorsal): Front/back.

• Medial / Lateral: Midline/side.

• Ipsilateral / Contralateral: Same side/opposite side.

• Proximal / Distal: Near/far from point of attachment.

• Superficial / Deep: Surface/internal.

Planes

• Sagittal: Left/right.

• Transverse: Top/bottom.

• Coronal (frontal): Front/back.

Abdominopelvic Regions

• Right hypochondriac | Epigastric | Left hypochondriac

• Right lumbar | Umbilical | Left lumbar

• Right iliac | Hypogastric | Left iliac

Key Body Regions

• Acromial: Shoulder

• Axillary: Armpit

• Brachial: Arm

• Femoral: Thigh

• Patellar: Kneecap

• Plantar: Sole of foot

• Occipital: Back of head

• Vertebral: Spine

Chapter 2: Chemical Basis of Life

The Importance of Chemistry in Anatomy & Physiology

Chemistry underlies all biological processes. Biochemistry studies the chemistry of living organisms and is essential for understanding physiological processes.

• Chemistry: Study of matter (composition and changes).

• Biochemistry: Chemistry of living organisms.

• Why it matters:

  • Body structures are made of chemicals.

  • Physiological processes are chemical reactions.

  • Medications and nutrition depend on chemical interactions.

  • Example: ATP production is a biochemical process essential for energy.

Structure of Matter

Matter consists of elements and atoms, which combine to form molecules and compounds.

• Matter: Anything with mass and space (solid, liquid, gas).

• Elements: Simplest form of matter; represented by chemical symbols.

• Atoms: Smallest unit of an element that retains its properties.

• Trace elements: Iron (Fe), Iodine (I), Zinc (Zn), etc.; essential in small amounts.

Atomic Structure

• Subatomic particles:

  • Proton (p+): +1 charge, in nucleus, mass = 1 amu.

  • Neutron (n0): No charge, in nucleus, mass = 1 amu.

  • Electron (e-): -1 charge, orbits nucleus, negligible mass.

• Atomic number: # of protons.

• Atomic weight: Protons + neutrons.

Isotopes & Radiation

• Isotopes: Same element, same protons, different neutrons.

• Stable isotopes: Do not decay.

• Radioactive isotopes: Unstable, emit radiation. Uses: Imaging, cancer treatment (e.g., Iodine-131 for thyroid).

Chemical Bonds

Chemical bonds form between atoms to create molecules and compounds. The octet rule states that atoms seek to fill their outer electron shells.

• Ionic Bond: Transfer of electrons; attraction between cation (+) & anion (−). Example: NaCl

• Covalent Bond: Sharing of electrons between atoms.

  • Nonpolar: Equal sharing (O2, H2).

  • Polar: Unequal sharing; partial charges (H2O).

• Hydrogen Bond: Weak attraction between polar molecules; crucial for DNA structure and protein folding.

Bond Types Table

Chemical Reactions

Chemical reactions involve the transformation of reactants into products. Types include synthesis, decomposition, exchange, and reversible reactions.

• Synthesis: Build large from small; requires protein synthesis.

• Decomposition (Catabolic): Breaking down; releases energy.

• Exchange: Parts of molecules swap.

• Reversible: Products can reform reactants.

Chemical Reactions Table

Acids, Bases, Salts, and Buffers

Acids, bases, and salts are electrolytes that ionize in water and conduct electricity. Buffers stabilize pH in biological systems.

• Acid: Releases H+ in water (HCl → H+ + Cl-).

• Base: Releases OH- or binds H+ (NaOH → Na+ + OH-).

• Salt: Formed from acid + base (NaCl).

• pH Scale (0-14):

  • 7 = neutral

  • <7 = acidic

  • >7 = basic/alkaline

• Normal blood pH: 7.35–7.45.

• Buffer systems: Stabilize pH (e.g., carbonic acid–bicarbonate system).

Chemical Constituents of Cells

Cells contain inorganic and organic substances essential for life.

Inorganic Substances

• Water (H2O): 70% body composition; solvent, buffer, transport, lubrication.

• Oxygen (O2): Cellular respiration → ATP.

• Carbon dioxide (CO2): Waste product, helps regulate pH.

• Inorganic salts: Na+, K+, Ca2+, Mg2+, Cl-, HCO3-; roles in muscle contraction, nerve conduction, pH regulation, blood clotting.

Organic Substances

• Carbohydrates: C, H, O (2:1 ratio H:O); primary energy source.

  • Monosaccharides: Glucose, fructose, galactose.

  • Disaccharides: Sucrose, lactose, maltose.

  • Polysaccharides: Starch (plants), glycogen (animals), cellulose (structural).

• Fats (Triglycerides): Glycerol + 3 fatty acids; energy storage.

  • Saturated: Solid (animal fats).

  • Unsaturated: Liquid (plant oils).

• Phospholipids: Glycerol + 2 fatty acids + phosphate; cell membranes.

• Steroids: 4-ring structure (cholesterol, hormones).

• Proteins: Monomers = amino acids (20 types); linked by peptide bonds.

  • Structure:

    • Primary: Amino acid sequence.

    • Secondary: Alpha helix/beta pleated sheet.

    • Tertiary: Folded 3D shape.

    • Quaternary: Multiple polypeptides (e.g., hemoglobin).

  • Functions: Structure, enzymes, transport, defense, hormones, movement.

  • Denaturation: Loss of structure/function due to pH, temperature, or chemicals.

• Nucleic Acids:

  • Nucleotides: Sugar + phosphate + nitrogenous base.

  • DNA (deoxyribonucleic acid): Double helix, deoxyribose sugar; bases: A-T, C-G; function: genetic code.

  • RNA (ribonucleic acid): Single strand, ribose sugar; bases: A-U, C-G; function: protein synthesis.

Subatomic Particles Table

Chapter 3: Cells – The Basic Units of Life

General Cell Concepts

Cells are the basic unit of structure and function in the body. They are measured in micrometers and undergo differentiation to become specialized.

• Cell: Basic unit of structure and function in the body.

• Differentiation: Process by which cells become specialized in structure/function.

• Structure and function are always related.

Composite (Typical) Cell

A typical cell consists of three major parts: nucleus, cytoplasm, and cell membrane.

• Nucleus: Control center (DNA, genetic synthesis, cell regulation).

• Cytoplasm: Organelles, cytosol.

• Cell membrane: Boundary, regulates entry/exit.

The Cell (Plasma) Membrane

The plasma membrane is a selectively permeable barrier composed of a phospholipid bilayer with embedded proteins and carbohydrates.

• Fluid mosaic model: Phospholipid bilayer + proteins + carbohydrates.

• Phospholipids: Hydrophilic heads, hydrophobic tails.

• Cholesterol: Stabilizes and reduces permeability.

• Proteins:

  • Channels/pores

  • Carriers/transporters

  • Receptors (signal transduction)

  • Enzymes

  • Cell Adhesion Molecules (CAMs)

• Carbohydrates: Cell recognition, interaction, self markers.

• Selectively permeable: Regulates entry/exit.

Organelles

Organelles are specialized structures within cells that perform specific functions.

• Ribosomes: Protein synthesis.

• Rough ER: Protein synthesis/transport.

• Smooth ER: Lipid synthesis, detoxification, Ca2+ storage.

• Golgi apparatus: Modifies, packages, and ships proteins.

• Vesicles: Transport/storage.

• Mitochondria: "Powerhouse," ATP from glucose.

• Lysosomes: Contain digestive enzymes ("suicide sacs").

• Peroxisomes: Detoxify harmful substances (H2O2 → H2O).

Cytoskeleton

• Microfilaments: Actin; movement & contraction.

• Microtubules: Tubulin; shape, transport, spindle fibers.

• Intermediate filaments: Support, structure.

Other Structures

• Centrosome: Produces spindle fibers for mitosis.

• Cilia: Short, numerous; move substances (respiratory tract, fallopian tubes).

• Flagella: Long, locomotion (only sperm).

• Microvilli: Increase surface area (small intestine).

Nucleus

• Nuclear envelope: Double membrane with pores.

• Nucleolus: Ribosome synthesis.

• Chromatin: DNA + proteins; condenses into chromosomes during division.

Membrane Transport

Substances move across cell membranes by passive or active mechanisms.

Passive (no ATP required)

• Diffusion: Movement from high → low concentration.

• Facilitated diffusion: Carrier proteins move substances.

• Osmosis: Diffusion of water through a selectively permeable membrane.

  • Hypertonic: Cell shrinks.

  • Hypotonic: Cell swells.

• Filtration: Pressure forces substances across membranes (e.g., kidneys).

Active (ATP required)

• Active transport: Low → high concentration (Na+/K+ pump).

• Endocytosis: Brings substances in.

  • Pinocytosis: Liquids.

  • Phagocytosis: Solids.

  • Receptor-mediated: Specific.

• Exocytosis: Vesicles fuse with membrane to release substances.

• Transcytosis: Combination of endo + exo; moves substances across cell.

Cell Cycle

The cell cycle consists of interphase (growth and DNA replication) and mitosis (cell division).

• Interphase: Growth & preparation (G1, S, G2).

  • G1: Growth, organelle replication

  • S: DNA replication

  • G2: Final growth

• Mitosis: Nuclear division.

  • Prophase: Chromatin condenses, spindle forms, nuclear membrane dissolves.

  • Metaphase: Chromosomes line up at equator.

  • Anaphase: Chromatids separate via spindle.

  • Telophase: Nuclei reform, chromosomes → chromatin.

  • Cytokinesis: Division of cytoplasm by cleavage furrow.

Control of Cell Division

Cell division is regulated by internal and external signals to ensure proper growth and development.

• Regulation: Controlled by growth factors, hormones, and checkpoints.

• Loss of control: Can lead to cancer (uncontrolled cell division).

Stem & Progenitor Cells

Stem cells are undifferentiated cells capable of giving rise to various cell types. Progenitor cells are partially specialized.

• Stem cells: Can become any cell type.

• Progenitor cells: Partially specialized.

Cell Death

Cell death occurs by apoptosis (programmed cell death) or necrosis (injury-induced death).

• Apoptosis: Programmed cell death; essential for development and health.

• Necrosis: Cell death due to injury or disease.

Example: Apoptosis removes damaged cells; necrosis can result from lack of oxygen.