Introduction to Anatomy and Physiology

Characteristics of Living Organisms

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

• Metabolism: The sum of all chemical reactions in the body, including anabolic (building up) and catabolic (breaking down) processes.

• Growth: Increase in size and/or number of cells.

• Responsiveness: Ability to sense and react to changes in the environment.

• Movement: Includes movement of the organism and movement of substances within the organism.

• Reproduction: Production of new cells or organisms.

• Homeostasis: Maintenance of a stable internal environment.

Body Systems Overview

The human body is organized into 11 major organ systems, each with specific functions.

• Integumentary (skin, hair, nails): Protection, temperature regulation.

• Skeletal (bones, joints): Support, movement, protection, blood cell production.

• Muscular (muscles): Movement, posture, heat production.

• Nervous (brain, spinal cord, nerves): Rapid communication, control, sensation.

• Endocrine (glands): Hormone production, regulation of metabolism and growth.

• Cardiovascular (heart, blood vessels): Transport of nutrients, gases, wastes.

• Lymphatic/Immune (lymph nodes, spleen): Defense, fluid balance.

• Respiratory (lungs, airways): Gas exchange.

• Digestive (stomach, intestines): Breakdown and absorption of nutrients.

• Urinary (kidneys, bladder): Waste elimination, water balance.

• Reproductive (ovaries, testes): Production of offspring.

Directional Terms

Directional terms describe the locations of structures relative to other structures or locations in the body.

• Superior/Inferior: Above/below

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

• Medial/Lateral: Toward the midline/away from the midline

• Proximal/Distal: Closer to/farther from the point of attachment

• Superficial/Deep: Toward/away from the body surface

Serous Membranes and Cavities

Serous membranes line body cavities and cover organs, producing serous fluid to reduce friction.

• Visceral layer: Covers the organ

• Parietal layer: Lines the cavity wall

• Pleural membrane: Surrounds the lungs

• Pericardial membrane: Surrounds the heart

• Serous fluid: Lubricates and reduces friction

Homeostasis and Feedback Loops

Homeostasis is maintained by feedback loops that regulate physiological processes.

• Negative feedback: Reverses a change to maintain balance (e.g., body temperature regulation).

• Positive feedback: Amplifies a change (e.g., blood clotting, childbirth).

• Stimulus: Change detected by the body

• Effector/Response: Organ or cell that acts to restore balance

The Chemistry of Life

Basic Atomic Structure

Atoms are the basic units of matter, composed of subatomic particles.

• Protons: Positively charged, found in the nucleus

• Neutrons: No charge, found in the nucleus

• Electrons: Negatively charged, orbit the nucleus

Atomic number = number of protons Mass number = protons + neutrons

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

• Radioisotopes: Unstable isotopes that emit radiation; used in medical imaging and cancer treatment

Electron Shells and Chemical Bonds

• 1st shell: holds up to 2 electrons

• 2nd shell: holds up to 8 electrons

• 3rd shell: holds up to 18 electrons

Valence electrons are electrons in the outermost shell and determine chemical reactivity.

• Chemical bonds: Forces that hold atoms together in molecules and compounds

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

• Covalent bonds: Sharing of electrons (can be polar or nonpolar)

• Hydrogen bonds: Weak attractions between polar molecules (e.g., water); responsible for surface tension

Polar covalent bond: Unequal sharing of electrons Nonpolar covalent bond: Equal sharing of electrons

Major Elements in the Human Body

• Oxygen (O)

• Carbon (C)

• Hydrogen (H)

• Nitrogen (N)

Types of Chemical Reactions

• Anabolic reactions: Build larger molecules from smaller ones (require energy)

• Catabolic reactions: Break down molecules (release energy)

• Endergonic: Absorb energy

• Exergonic: Release energy

• Oxidation-reduction (redox) reactions: Transfer of electrons; oxidation = loss of electrons, reduction = gain of electrons

Enzymes and Activation Energy

• Enzyme: Biological catalyst that speeds up reactions by lowering activation energy

• Activation energy: Minimum energy required to start a reaction

• Factors affecting enzyme activity: Temperature, pH, substrate concentration, inhibitors

• Enzymes are proteins and can be denatured by heat, pH changes, or chemicals

Acids, Bases, and Buffers

• Acid: Releases H+ ions in solution

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

• Buffer: Resists changes in pH

• Electrolytes: Substances that dissociate into ions in water and conduct electricity

pH scale: 0 (acidic) to 14 (basic), 7 is neutral

Macromolecules

There are four major classes of biological macromolecules, each with unique structures and functions.

• Fatty acid: Long hydrocarbon chain; saturated (no double bonds, solid at room temp) vs. unsaturated (one or more double bonds, liquid at room temp)

• Triglyceride: Glycerol + 3 fatty acids; main form of stored fat

• Phospholipid: Glycerol + 2 fatty acids + phosphate group; major component of cell membranes

• Sterols (steroids): Lipids with four fused rings (e.g., cholesterol)

• Good fats: Unsaturated (e.g., omega-3 fatty acids); Bad fats: Saturated and trans fats (increase cardiovascular risk)

• Peptide bonds: Link amino acids in proteins

• Protein structure: Primary (sequence), secondary (alpha helix/beta sheet), tertiary (3D folding), quaternary (multiple polypeptides)

• Denaturation: Loss of protein structure due to heat, pH, or chemicals

• Enzymes: Proteins that catalyze reactions

• DNA/RNA base pairing: DNA: A-T (2 bonds), G-C (3 bonds); RNA: A-U, G-C

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

• Phosphodiester bonds: Link nucleotides in DNA/RNA

The Cell

Basic Cell Structure

Most animal cells share three basic components:

• Plasma membrane: Outer boundary, selectively permeable

• Cytoplasm: Fluid and organelles inside the cell

• Nucleus: Contains genetic material

Cell Organelles and Their Functions

Plasma Membrane Structure

• Phospholipid bilayer: Hydrophilic heads, hydrophobic tails

• Proteins: Channels, carriers, receptors

• Cholesterol: Stabilizes membrane fluidity

• Carbohydrates: Cell recognition

Fluid mosaic model: Describes the dynamic arrangement of membrane components

Transport Across the Membrane

• Passive transport: No energy required (diffusion, osmosis, facilitated diffusion)

• Active transport: Requires energy (e.g., Na+/K+ pump)

• Simple diffusion: Movement of small, nonpolar molecules (e.g., O2, CO2)

• Facilitated diffusion: Movement via protein channels/carriers (e.g., glucose)

• Osmosis: Diffusion of water across a membrane

• Isotonic: Equal solute concentration

• Hypotonic: Lower solute concentration outside; water enters cell

• Hypertonic: Higher solute concentration outside; water leaves cell

• Exocytosis: Vesicles fuse with membrane to release contents

• Endocytosis: Cell engulfs material (includes pinocytosis and phagocytosis)

• Na+/K+ pump: Moves 3 Na+ out, 2 K+ in per ATP

Cytoskeleton and Cell Extensions

• Microfilaments: Actin, cell movement

• Intermediate filaments: Structural support

• Microtubules: Tubulin, cell shape, transport

• Cell extensions: Cilia (movement), flagella (movement), microvilli (increase surface area)

Genetics and Protein Synthesis

• Gene: Segment of DNA coding for a protein

• Exons: Coding regions

• Mutations: Changes in DNA sequence

• Mutagens: Agents causing mutations

• Promoter: DNA region where transcription starts

• Apoptosis: Programmed cell death

Central dogma: DNA --(transcription)--> mRNA --(translation)--> protein

• DNA replication: DNA to DNA

• Transcription: DNA to mRNA

• Translation: mRNA to protein (via tRNA and ribosomes)

• RNA processing: Introns removed, exons spliced; mature mRNA leaves nucleus

• Base pairing: DNA: A-T, G-C; RNA: A-U, G-C

Protein Pathway in the Cell

Proteins are synthesized and processed through a specific pathway:

• Nucleus (gene transcription)

• Rough ER (translation and folding)

• Transport vesicle

• Golgi apparatus (modification and packaging)

• Secretory vesicle

• Cell membrane (exocytosis)

Example: Insulin is synthesized in the pancreas, processed through the ER and Golgi, and secreted into the bloodstream.

Additional info: Some details, such as the specific slide numbers or images referenced, were not available in the text and have been supplemented with standard academic context for completeness.