Foundations of Anatomy & Physiology: The Human Body, Chemistry, and Cells

Chapter 1: The Human Body

Anatomy vs. Physiology

Anatomy is the study of the structure of body parts, while physiology focuses on their function. The principle of complementarity states that structure determines function.

• Anatomy: Structure

• Physiology: Function

• Principle of Complementarity: Structure determines function

Levels of Organization

The human body is organized hierarchically from the simplest to the most complex levels.

• Chemical → Cellular → Tissue → Organ → Organ System → Organism

Organ Systems

There are 11 major organ systems in the human body, each with specific functions.

• Organ systems: Integumentary, skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic, respiratory, digestive, urinary, reproductive

Necessary Life Functions

Life depends on several essential functions to maintain homeostasis and survival.

• Maintaining boundaries

• Movement

• Responsiveness

• Digestion

• Metabolism

• Excretion

• Reproduction

• Growth

Survival Needs

Organisms require certain materials and conditions to survive.

• Nutrients

• Oxygen

• Water

• Normal body temperature

• Appropriate atmospheric pressure

Homeostasis

Homeostasis is the maintenance of a stable internal environment, primarily through feedback systems.

• Negative feedback: Most common; reduces or shuts off the original stimulus (e.g., body temperature, blood glucose)

• Positive feedback: Rare; amplifies the original stimulus (e.g., childbirth, blood clotting)

Homeostatic Control Components

• Receptor: Senses change

• Control center: Sets the set point

• Effector: Carries out response

Anatomical Terms & Body Planes

Directional and regional terms help describe locations and relationships in the body.

• Directional terms: Superior, inferior, anterior, posterior, medial, lateral

• Planes: Sagittal (left/right), coronal (front/back), transverse (top/bottom), oblique (angled cuts)

Body Cavities

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

• Dorsal cavity: Cranial + vertebral (protected by meninges)

• Ventral cavity: Thoracic (pleural, mediastinum, pericardial) + abdominopelvic (abdominal + pelvic)

Chapter 2: Chemistry Comes Alive

States of Matter

Matter exists in three main states, each with distinct properties.

• Solids: Fixed shape and volume

• Liquids: Fixed volume, variable shape

• Gases: Variable shape and volume

Forms of Energy

Energy is the capacity to do work and exists in several forms.

• Chemical

• Electrical

• Mechanical

• Radiant (light, heat, X-rays)

Energy conversions lose some energy as heat.

Elements & Atoms

Elements are pure substances; atoms are their smallest units.

• 96% of body: C, O, H, N

• Atomic number: Number of protons

• Atomic mass: Protons + neutrons

Chemical Bonds

Atoms combine via chemical bonds to form molecules.

• Ionic: Transfer of electrons

• Covalent: Sharing of electrons

• Hydrogen bonds: Weak attractions

Chemical Reactions

Chemical reactions rearrange atoms to form new substances.

• Synthesis: Build molecules

• Decomposition: Break molecules

• Exchange: Bonds made and broken

• Redox: Electron transfer (oxidation = loss, reduction = gain)

Water Properties

Water is vital for life due to its unique properties.

• High heat capacity

• High heat of vaporization

• Polar solvent

• Reactivity

• Cushioning

pH Scale

The pH scale measures hydrogen ion concentration.

• Range: 0–14

• Acids release H+; bases accept H+

• Buffers resist pH changes

Formula:

$\text{pH} = -\log_{10}[\text{H}^+]$

Organic Molecules

Organic molecules are carbon-based and essential for life.

• Carbohydrates: Quick energy

• Lipids: Energy storage, insulation, membranes

• Proteins: Structure, enzymes

• Nucleic acids: Genetic material (DNA/RNA), ATP = energy currency

Trace Elements

Trace elements are required in minute amounts, often as enzyme cofactors.

• Examples: Zn, Cu, I, Se

Lipids

Lipids are hydrophobic molecules important for energy and cell membranes.

• Saturated fats: Solid (animal fat)

• Unsaturated fats: Liquid (oils)

• Trans fats: Unhealthy

• Omega-3 fatty acids: "Heart healthy"

Phospholipids

Phospholipids are amphipathic molecules forming cell membranes.

• Hydrophilic heads

• Hydrophobic tails

Enzymes

Enzymes are biological catalysts that lower activation energy, making reactions faster and more specific.

Acids & Bases

Acids are proton donors; bases are proton acceptors.

• Acids: HCl, H2CO3

• Bases: HCO3-, NH3

Carbohydrates

• Monosaccharides: Glucose

• Disaccharides: Sucrose, lactose

• Polysaccharides: Glycogen, starch

Proteins

Proteins are made of amino acids; their function depends on shape (denaturation disrupts).

Nucleic Acids

• DNA: Genetic code

• RNA: Protein synthesis

• ATP: Energy

Chapter 3: Cells

Extracellular Materials

Materials outside cells include interstitial fluid, blood plasma, cerebrospinal fluid, secretions, and extracellular matrix (acts as "cell glue").

Membrane Proteins

Proteins in the plasma membrane can be integral (span bilayer, channels/receptors) or peripheral (surface, enzymes, support).

Facilitated Diffusion

Facilitated diffusion uses carriers or channels for specific binding; can saturate or leak (gated channels).

Cell Theory

• Cells are the basic unit of life

• All living things are made of cells

• Cells come from other cells

Generalized Cell Parts

• Plasma membrane

• Cytoplasm

• Nucleus

Plasma Membrane

The plasma membrane is a phospholipid bilayer (fluid mosaic model) with proteins for transport, receptors, enzymes, recognition, joining, and anchoring.

Transport Mechanisms

• Passive: No ATP (diffusion, osmosis, facilitated diffusion)

• Active: Requires ATP (pumps, endocytosis, exocytosis)

Cell Organelles

• Mitochondria: ATP powerhouse

• Ribosomes: Protein synthesis

• Rough ER: Protein processing

• Smooth ER: Lipid metabolism, detox

• Golgi apparatus: Modifies, packages proteins

• Lysosomes: Digestion

• Peroxisomes: Detox/free radical neutralization

• Cytoskeleton: Structural support

Nucleus

• Nuclear envelope

• Nucleolus (rRNA synthesis)

• Chromatin

Cell Cycle

• Interphase (G1, S, G2)

• Mitosis (prophase, metaphase, anaphase, telophase)

• Cytokinesis

Diffusion vs. Osmosis

• Diffusion: Movement of molecules

• Osmosis: Movement of water through a selectively permeable membrane

Osmolarity vs. Osmosis

• Osmolarity: Measurement of solute concentration

• Osmosis: Water movement through a membrane

Hydrostatic vs. Osmotic Pressure

• Hydrostatic: Outward water pressure

• Osmotic: Inward pull of water

Tonicity

• Isotonic: Equal solute

• Hypertonic: Higher solute outside, cell shrinks

• Hypotonic: Lower solute outside, cell swells

Resting Membrane Potential (RMP)

RMP is maintained mainly by K+ diffusion and the sodium-potassium pump; essential for nerve/muscle excitability.

Formula:

$\text{RMP} \approx -70\ \text{mV}$

Cell Communication

• CAMs: Cell adhesion molecules anchor, attract WBCs, signal for healing

• Receptors bind ligands (hormones, neurotransmitters) and trigger intracellular signals

Introns and Exons

• Introns: Non-coding segments of DNA/RNA, spliced out during RNA processing

• Exons: Coding segments, remain after splicing, contain instructions for making proteins

Plant vs. Animal Cells

Feature	Plant Cells	Animal Cells
Cell Wall	Present (cellulose)	Absent
Chloroplasts	Present (photosynthesis)	Absent
Vacuoles	Large central vacuole	Small, temporary vacuoles
Shape	Rectangular/box-like	Rounded/irregular
Energy Storage	Starch	Glycogen

Glycocalyx

The glycocalyx is a sugar coat on the cell surface for recognition.

Endocytosis and Exocytosis

• Endocytosis: Phagocytosis, pinocytosis, receptor-mediated

• Exocytosis: Release of substances from the cell

Cell Cycle Checkpoints

Restriction point in G1 determines if a cell divides or enters G0 (resting).

Example: Blood glucose regulation is a classic example of negative feedback, where increased blood glucose triggers insulin release to lower it.