Introduction to Anatomy & Physiology

Definitions and Relationships

• 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—how the body parts work and carry out their life-sustaining activities.

• Relationship: Anatomy and physiology are closely related; structure determines function, and function reflects structure.

Characteristics of Living Things

• Organization: Living things are highly organized, from the molecular to the organismal level.

• Metabolism: All chemical reactions occurring in the body.

• Responsiveness: Ability to sense and respond to stimuli.

• Growth, development, reproduction, and homeostasis are also key characteristics.

Levels of Organization in the Human Body

• Chemical level: Atoms and molecules.

• Cellular level: Cells and their organelles.

• Tissue level: Groups of similar cells.

• Organ level: Contains two or more types of tissues.

• Organ system level: Organs that work closely together.

• Organismal level: All organ systems combined to make the whole organism.

• Most complex: Organismal level; Least complex: Chemical level.

Cell Theory

• All living things are composed of cells.

• The cell is the basic unit of life.

• All cells arise from pre-existing cells.

• Cell theory is fundamental to understanding human structure and function.

Tissues and Organs

• Tissues: Groups of similar cells performing a common function.

• Four types: Epithelial, connective, muscle, and nervous tissue.

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

• Organ systems: Groups of organs that work together (e.g., digestive, respiratory, circulatory systems).

Homeostasis

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

• Regulated by feedback mechanisms (negative and positive feedback).

• Disruption can lead to disease or dysfunction.

Feedback Mechanisms

• Negative feedback: Reduces the effect of the original stimulus (e.g., body temperature regulation).

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

Basic Chemistry for Anatomy & Physiology

Atoms and Elements

• Atom: The smallest unit of matter retaining the properties of an element.

• Subatomic particles: Protons (+), neutrons (0), electrons (−).

• Atoms have a nucleus (protons and neutrons) and electron shells.

• Element: A substance that cannot be broken down into simpler substances by chemical means (e.g., carbon, oxygen).

• Common elements in the body: Oxygen, carbon, hydrogen, nitrogen.

Atomic Number, Mass Number, and Isotopes

• Atomic number: Number of protons in the nucleus.

• Mass number: Number of protons plus neutrons.

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

Ions and Chemical Bonds

• Ion: An atom or molecule with a net electric charge due to the loss or gain of electrons.

• Cation: Positively charged ion (lost electrons).

• Anion: Negatively charged ion (gained electrons).

• Ionic bonds: Formed by the transfer of electrons.

• Covalent bonds: Formed by the sharing of electrons (can be polar or non-polar).

• Hydrogen bonds: Weak attractions between polar molecules.

Water and Solutions

• Water is vital for life due to its solvent properties, high heat capacity, and role in chemical reactions.

• Electrolyte: A substance that dissociates into ions in solution and conducts electricity (e.g., NaCl in water).

Acids, Bases, and pH

• pH: A measure of hydrogen ion concentration; scale from 0 (acidic) to 14 (basic), with 7 as neutral.

• Blood pH is tightly regulated (about 7.35–7.45).

• Buffer: A substance that minimizes changes in pH.

Chemical Reactions

• Synthesis reactions: Build larger molecules from smaller ones ().

• Decomposition reactions: Break down molecules ().

• Exchange reactions: Involve both synthesis and decomposition ().

• Enzymes: Biological catalysts that speed up reactions by lowering activation energy.

Biological Molecules

Carbohydrates

• Composed of carbon, hydrogen, and oxygen.

• Function: Provide energy (e.g., glucose), structural support (e.g., cellulose in plants).

• Types: Monosaccharides, disaccharides, polysaccharides.

Lipids

• Composed mainly of carbon and hydrogen.

• Function: Energy storage, insulation, cell membrane structure.

• Types: Triglycerides, phospholipids, steroids.

• Saturated vs. unsaturated fats: Saturated have no double bonds; unsaturated have one or more double bonds.

Proteins

• Composed of amino acids (20 types).

• Structure: Four levels (primary, secondary, tertiary, quaternary).

• Function: Enzymes, structural support, transport, signaling.

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

Nucleic Acids

• DNA and RNA are polymers of nucleotides.

• Function: Store and transmit genetic information.

• DNA: Double helix, base pairs (A-T, C-G).

• RNA: Single-stranded, types include mRNA, tRNA, rRNA.

High-Energy Compounds

• ATP (adenosine triphosphate) is the primary energy carrier in cells.

• Energy is stored in the phosphate bonds.

Cell Structure and Function

Cell Organization and Organelles

• Cells contain specialized structures called organelles, each with specific functions.

Cytoskeleton Components

• Microfilaments: Actin filaments, provide cell shape and movement.

• Intermediate filaments: Provide mechanical support.

• Microtubules: Tubulin polymers, involved in cell division and transport.

Centrioles and Cilia

• Centrioles: Organize microtubules during cell division.

• Cilia: Hair-like projections for movement of substances across cell surfaces.

Plasma Membrane

• Composed of a phospholipid bilayer with embedded proteins.

• Functions: Selective permeability, protection, communication.

Membrane Transport

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

• Active transport: Requires energy (ATP) to move substances against concentration gradients.

• Vesicular transport: Endocytosis (phagocytosis, pinocytosis), exocytosis.

Tonicity

• Isotonic: No net water movement; cell remains the same size.

• Hypotonic: Water enters cell; cell swells.

• Hypertonic: Water leaves cell; cell shrinks.

Nucleus and Genetic Material

Nucleus Structure and Function

• Contains DNA, controls cell activities.

• Nuclear envelope: Double membrane with pores for transport.

• Nucleolus: Site of ribosome synthesis.

DNA Organization and Protein Synthesis

• DNA is organized into chromosomes; humans have 46 (23 pairs).

• Genes encode information for protein synthesis.

• Protein synthesis involves transcription (DNA to mRNA) and translation (mRNA to protein).

Cell Cycle and Division

• Interphase: G0 (rest), G1 (growth), S (DNA synthesis), G2 (preparation for mitosis).

• Mitosis: Prophase, metaphase, anaphase, telophase.

• Cytokinesis: Division of cytoplasm, producing two daughter cells.

Additional info:

• Some explanations and examples have been expanded for clarity and completeness.