BIOL 2401 A&P-1 Unit 1: Study Guide Notes

The Human Body: An Orientation

Topics of Anatomy and Physiology

Anatomy and physiology are two closely related branches of biology that study the structure and function of the human body.

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

• Physiology: The study of the function of the body’s structural machinery.

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.

• Example: Bones can support and protect body organs because they contain hard mineral deposits.

Levels of Structural Organization

The human body is organized into several levels, each building on the previous one:

• 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.

Necessary Life Functions

To maintain life, the body must perform several functions:

• Maintaining boundaries

• Movement

• Responsiveness

• Digestion

• Metabolism

• Excretion

• Reproduction

• Growth

Organ Systems and Their Functions

The body contains 11 organ systems, each with specific functions:

• Integumentary (protection, temperature regulation)

• Skeletal (support, movement, protection)

• Muscular (movement, posture, heat production)

• Nervous (control, coordination, response to stimuli)

• Endocrine (hormone production, regulation)

• Cardiovascular (transport of nutrients, gases, wastes)

• Lymphatic (immunity, fluid balance)

• Respiratory (gas exchange)

• Digestive (breakdown and absorption of nutrients)

• Urinary (waste elimination, water balance)

• Reproductive (production of offspring)

Survival Needs

Humans require several factors for survival:

• Nutrients: For energy and cell building.

• Oxygen: Essential for energy release (ATP production).

• Water: Most abundant chemical in the body; site of chemical reactions.

• Normal body temperature: Necessary for chemical reactions to occur at life-sustaining rates.

• Appropriate atmospheric pressure: Required for proper breathing and gas exchange.

Homeostasis and Feedback Loops

Homeostasis is the maintenance of a stable internal environment. It is controlled through feedback loops:

• Components: Receptor (detects change), Control center (processes information), Effector (carries out response).

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

• Positive feedback: Enhances the original stimulus (e.g., platelet plug formation in blood clotting).

Chemistry Comes Alive

Matter and Energy

Matter is anything that occupies space and has mass. Energy is the capacity to do work or put matter into motion.

• Potential energy: Stored energy (e.g., chemical bonds).

• Kinetic energy: Energy in action (e.g., movement of muscles).

• Other forms: Electrical, mechanical, radiant, chemical.

• Energy conversions are not 100% efficient; some energy is lost as heat.

Atomic Structure

• Protons: Positive charge, located in nucleus.

• Neutrons: No charge, located in nucleus.

• Electrons: Negative charge, orbit nucleus.

• Atomic number: Number of protons.

• Mass number: Protons + neutrons.

• Atomic weight: Average mass of all isotopes.

• Isotopes: Atoms with same number of protons but different neutrons (e.g., Carbon-12, Carbon-14).

• Radioisotopes: Unstable isotopes that decay, emitting radiation.

Molecules, Compounds, and Mixtures

• Molecule: Two or more atoms bonded together (e.g., O2).

• Compound: Two or more different atoms bonded (e.g., H2O).

• Mixtures: Physical combinations of substances (e.g., solutions, colloids, suspensions).

• Distinguishing mixtures and compounds: Compounds have chemical bonds; mixtures do not.

Chemical Bonding

• Octet rule: Atoms tend to gain, lose, or share electrons to achieve 8 in their valence shell.

• Chemically inert elements: Have full valence shells (e.g., noble gases).

• Reactive elements: Do not have full valence shells.

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

• Covalent bonds: Sharing of electrons (e.g., H2O, CO2).

• Hydrogen bonds: Weak attractions between polar molecules.

• Polar covalent: Unequal sharing (e.g., H2O).

• Non-polar covalent: Equal sharing (e.g., CO2).

Chemical Reactions

• Synthesis: Building larger molecules (A + B → AB).

• Decomposition: Breaking down molecules (AB → A + B).

• Exchange: Rearrangement of parts (AB + C → AC + B).

• Redox reactions: Involve electron transfer.

• Exergonic: Release energy.

• Endergonic: Absorb energy.

• Reversible reactions: Can proceed in both directions.

• Factors influencing rate: Temperature, concentration, particle size, catalysts.

Inorganic Compounds

• Water: High heat capacity, high heat of vaporization, polar solvent, reactivity, cushioning.

• Salts: Ionic compounds that dissociate in water (e.g., NaCl).

• Acids: Proton donors (release H+).

• Bases: Proton acceptors (release OH-).

pH and Acid-Base Balance

• pH scale: Measures [H+] concentration; 0-14 scale.

• Acidic: pH < 7; Basic: pH > 7; Neutral: pH = 7.

• Neutralization: Acid + base → salt + water.

• Strong acids/bases: Completely dissociate (e.g., HCl, NaOH).

• Weak acids/bases: Partially dissociate (e.g., H2CO3, HCO3-).

Organic Compounds

• Dehydration synthesis: Removes water to form bonds.

• Hydrolysis: Adds water to break bonds.

• Carbohydrates: Sugars and starches; energy source.

• Lipids: Fats, oils, steroids; energy storage, insulation.

• Proteins: Amino acid polymers; structure, enzymes, transport.

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

• Enzyme action: Enzymes lower activation energy, speeding up reactions.

• DNA structure: Double helix; genetic information storage.

• ATP: Main energy currency of the cell.

Acid-Base Chemistry

Acid-Base Balance: Acidosis vs. Alkalosis

• Acidosis: Blood pH below 7.35.

• Alkalosis: Blood pH above 7.45.

Bicarbonate Buffer System

• Buffers resist changes in pH.

• When a strong acid is added, bicarbonate (HCO3-) binds H+ to form carbonic acid (H2CO3).

• When a strong base is added, carbonic acid releases H+ to neutralize the base.

• Key equations:

  • $\mathrm{CO_2 + H_2O \leftrightarrow H_2CO_3 \leftrightarrow H^+ + HCO_3^-}$

  • $\mathrm{H_2CO_3 \leftrightarrow H^+ + HCO_3^-}$

• Alkaline reserve: The available HCO3- in the blood.

Protein Buffer System

• Proteins act as buffers by binding or releasing H+.

Respiratory Regulation of H+

• High [H+] (acidosis): Increased CO2 exhalation (hyperventilation) lowers H+.

• Low [H+] (alkalosis): Decreased CO2 exhalation (hypoventilation) raises H+.

Types of Acid-Base Imbalances

Type	Causes	Examples
Respiratory Acidosis	Impaired ventilation	Emphysema, chronic bronchitis
Respiratory Alkalosis	Excessive ventilation	Panic attack, asthma, pneumonia
Metabolic Acidosis	Increased acid or loss of base	Severe diarrhea, diabetes
Metabolic Alkalosis	Loss of acid or excess base	Vomiting, excessive antacid use

Cells: The Living Units

Generalized Cell Structure

• Plasma membrane: Outer boundary; regulates entry/exit.

• Cytoplasm: Contains organelles and cytosol.

• Nucleus: Control center; contains DNA.

Plasma Membrane Structure and Function

• Membrane lipids: Phospholipid bilayer with cholesterol for stability.

• Membrane proteins: Transport, receptors, enzymes, cell recognition, attachment.

• Glycocalyx: Carbohydrate-rich area for cell recognition and protection.

• Cell junctions: Tight junctions, desmosomes, gap junctions.

Membrane Transport

• Passive processes: No energy required.

  • Diffusion: Movement from high to low concentration.

  • Osmosis: Diffusion of water.

• Solutions:

  • Isotonic: No net water movement.

  • Hypertonic: Water leaves cell; cell shrinks.

  • Hypotonic: Water enters cell; cell swells.

• Active transport: Requires energy (ATP).

  • Primary: Na+-K+ pump.

  • Secondary: Na+-glucose co-transport.

• Endocytosis: Cell engulfs material (phagocytosis, pinocytosis, receptor-mediated).

Resting Membrane Potential (RMP)

• Generated by differences in K+ and Na+ concentrations across the membrane.

• Maintained by active transport (Na+-K+ pump).

Cytoplasmic Organelles

• Mitochondria: ATP production.

• Ribosomes: Protein synthesis.

• Rough ER: Protein modification and transport.

• Smooth ER: Lipid synthesis, detoxification.

• Golgi apparatus: Packaging and shipping of proteins/lipids.

• Peroxisomes: Breakdown of fatty acids, detoxification.

• Lysosomes: Digestive enzymes for waste removal.

Cytoskeleton and Cellular Extensions

• Microfilaments, intermediate filaments, microtubules: Structural support, movement.

• Centrosomes and centrioles: Organize microtubules during cell division.

• Cilia: Move substances across cell surface.

• Flagella: Propel the cell (e.g., sperm).

• Microvilli: Increase surface area for absorption.

Nucleus and Genetic Material

• Nucleus: Contains nuclear envelope, nucleolus, chromatin.

• Chromatin: DNA and proteins; condenses to form chromosomes during cell division.

Cell Cycle and Division

• Mitosis: Division of nucleus (prophase, metaphase, anaphase, telophase).

• Cytokinesis: Division of cytoplasm.

• DNA replication: Copying DNA before cell division.

Protein Synthesis

• Transcription: DNA → mRNA (in nucleus).

• Translation: mRNA → polypeptide (at ribosome).

• tRNA: Brings amino acids to ribosome.

• Genetic code: Triplet codons specify amino acids.

• Information transfer: DNA → RNA → Protein.