Anatomy & Physiology: Foundational Concepts and Levels of Organization

Important Terms & Concepts

This guide summarizes foundational terms and concepts in Anatomy & Physiology, focusing on the organization of the human body, chemical and cellular levels, and tissue structure. Mastery of these topics is essential for understanding more advanced physiological processes.

Chapter 1: Introduction to the Human Body

Levels of Organization

• Chemical: Atoms and molecules fundamental to life.

• Cellular: Basic unit of structure and function in living things.

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

• Organ: Structures composed of two or more tissue types.

• Organ System: Groups of organs working together for a common purpose.

Example: Muscle tissue (tissue level) forms the heart (organ), which is part of the cardiovascular system (organ system).

Metabolism and Homeostasis

• Metabolism: All chemical reactions in the body, including catabolism (breakdown) and anabolism (synthesis).

• Homeostasis: Maintenance of a stable internal environment (e.g., temperature, pH, glucose levels).

• Feedback Systems:

  • Negative feedback: Reverses a change (e.g., regulation of blood sugar).

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

Anatomical Positions and Body Regions

• Standard anatomical position: Body erect, facing forward, arms at sides, palms forward.

• Body regions:

  • Cephalic (head): cranial, facial, orbital, nasal, oral

  • Cervical (neck)

  • Trunk: thoracic, abdominal, pelvic

  • Upper extremity: brachial, antebrachial, carpal, manual

  • Lower extremity: femoral, crural, pedal

• Directional terms: superior/inferior, anterior/posterior, medial/lateral, proximal/distal, superficial/deep

• Body planes: sagittal, frontal (coronal), transverse (horizontal)

Body Cavities and Membranes

• Dorsal cavity: cranial and vertebral cavities

• Ventral cavity: thoracic (pleural, pericardial, mediastinum) and abdominopelvic (abdominal, pelvic) cavities

• Serous membranes: line body cavities and cover organs (pleura, pericardium, peritoneum)

Chapter 2: Chemical Level of Organization

Chemical Elements and Atoms

• Elements: Pure substances; 26 found in the human body (e.g., C, H, O, N, Ca, P, K, S, Na, Cl, Mg, Fe, I, etc.)

• Atoms: Smallest units of elements; composed of protons, neutrons, electrons

• Atomic number: Number of protons

• Mass number: Protons + neutrons

• Isotopes: Atoms with same number of protons but different neutrons

Atoms, Molecules, and Chemical Bonds

• Electron shells: Energy levels where electrons reside; valence shell determines reactivity

• Ions: Atoms that have gained or lost electrons (cations: +, anions: -)

• Chemical bonds:

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

  • Covalent bonds: Sharing of electrons (e.g., H2O, O2, CH4)

  • Hydrogen bonds: Weak attractions between polar molecules (important in water, DNA)

Chemical Reactions and Compounds

• Synthesis reactions: Anabolism (building up, e.g., $N + 3H \rightarrow NH_3$)

• Decomposition reactions: Catabolism (breaking down, e.g., $CH_4 \rightarrow C + 4H$)

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

Inorganic and Organic Compounds

• Inorganic: Water, salts, acids, bases

• pH scale: Measures hydrogen ion concentration; $pH = -\log[H^+]$

• Buffers: Maintain pH stability (e.g., $H_2CO_3 \leftrightarrow H^+ + HCO_3^-$)

• Organic: Contain carbon; include carbohydrates, lipids, proteins, nucleic acids

Table: Major Organic Compounds

Type	Monomer	Function
Carbohydrates	Monosaccharides (glucose)	Energy source
Lipids	Fatty acids, glycerol	Energy storage, cell membranes
Proteins	Amino acids	Structure, enzymes, signaling
Nucleic acids	Nucleotides	Genetic information (DNA, RNA)

Macromolecules

• Carbohydrates: Sugars and starches; $C_6H_{12}O_6$ (glucose)

• Lipids: Triglycerides, phospholipids, steroids

• Proteins: Polymers of amino acids; structure determined by primary, secondary, tertiary, quaternary levels

• Enzymes: Proteins that catalyze reactions

• Nucleic acids: DNA and RNA; store and transmit genetic information

Chapter 3: Cellular Level of Organization

Generalized Animal Cell Structure

• Plasma membrane: Phospholipid bilayer with proteins; controls entry/exit of substances

• Cytoplasm: Cytosol (fluid) and organelles

• Nucleus: Contains DNA, controls cell activities

Organelles and Their Functions

• Ribosomes: Protein synthesis

• Endoplasmic reticulum (ER): Rough ER (with ribosomes, protein synthesis), Smooth ER (lipid synthesis)

• Golgi complex: Modifies, sorts, packages proteins/lipids

• Lysosomes: Digestive enzymes

• Peroxisomes: Break down fatty acids, detoxification

• Mitochondria: ATP production via cellular respiration

Cytoskeleton

• Microfilaments: Actin, muscle contraction

• Microtubules: Tubulin, cell shape, transport, cilia/flagella

• Intermediate filaments: Structural support

Cell Cycle

• Interphase: G1, S (DNA synthesis), G2

• Mitosis: Prophase, metaphase, anaphase, telophase

• Cytokinesis: Division of cytoplasm

Chapter 4: Tissue Level of Organization

Types of Tissues

• Epithelial: Covers surfaces, lines cavities

• Connective: Supports, protects, binds tissues

• Muscle: Movement

• Nervous: Transmits impulses

Epithelial Tissue

• Features: Free (apical) surface, basement membrane, avascular

• Types (by cell shape): Squamous, cuboidal, columnar, transitional

• Glandular epithelium: Endocrine (hormones), exocrine (ducts, e.g., sweat, salivary glands)

Additional info: For all topics, students should be able to define terms, give examples, and relate structure to function. Understanding feedback systems, chemical reactions, and cell/tissue organization is foundational for later study of organ systems.