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Anatomy: Study of body structure.
- Microscopic Anatomy: Structures observed with a microscope.
- Macroscopic Anatomy (Gross): Structures visible to the naked eye.
Physiology: Study of body functions and how body parts work together.
- Key concept: Homeostasis.
- Animal Physiology: Study in animals.
- Comparative Physiology: Study across species.
Systemic Approach: Study of structures and functions within an organ system (e.g., nervous system).
Principle of Complementarity: Function reflects structure; form determines function.

Standardized frame of reference for anatomical descriptions: subject faces observer, palms forward.
Key terms:
- Prone: face down.
- Supine: face up.
Body Planes: described as:
1. Sagittal Plane: divides into right and left sections.
2. Frontal (Coronal) Plane: divides into anterior and posterior sections.
3. Transverse Plane: divides into upper and lower sections.

Homeostasis: The intricate processes responsible for maintaining a stable internal environment, regardless of external fluctuations.
Stress: Refers to any condition or factor that poses a challenge to homeostasis, invoking physiological responses.
Components involved in homeostatic regulation:
- Receptors: Detect changes in the environment and send signals to control centers.
- Control Centers: Analyze information and determine the necessary response to maintain homeostasis.
- Effectors: Execute the responses through muscle contractions or glandular secretion to restore balance.

Negative Feedback: Reverses deviation from set point; common for maintaining homeostasis (e.g., temperature regulation).
Positive Feedback: Amplifies change, leads to rapid alterations in body state (e.g., childbirth).

Matter: Composed of elements, has mass and volume.
Atom: Smallest part of an element; nucleus contains protons and neutrons; electrons orbit nucleus.
Atomic properties: Atomic number (protons), Mass number (protons + neutrons).
Ions: Charged atoms; cations (positive), anions (negative).
Isotopes: Variants of elements with different neutron counts.

Types: Ionic, Covalent, Hydrogen Bonds.
Ionic Bonds: Formed by attraction of opposite charges.
Covalent Bonds: Electrons shared between atoms; can be single, double, or triple.
Hydrogen Bonds: Weak attractions between polar molecules (important in water).

Water (H₂O): Constitutes approximately 70% of cellular composition, is essential for life, serving crucial functions such as:
- Acting as a solvent for biochemical reactions.
- Regulating temperature through high heat capacity.
- Facilitating chemical reactivity in metabolic processes.
- Providing lubrication in joint and body cavity functions.
Acids/Bases: Substances that can donate protons (acids) or accept protons (bases), significantly influencing the characteristics and behavior of solutions.
pH Scale: A logarithmic scale ranging from 0 to 14 that quantifies the acidity or alkalinity of solutions, critical for maintaining proper biological functions.

Macromolecules: Large organic compounds made of repeating subunits (monomers).
- Carbohydrates: Monosaccharides (simple sugars), disaccharides (two sugars), polysaccharides (many sugars).
- Proteins: Composed of amino acids, exhibit various functions (structural, communication, protection).
- Levels of Protein Structure: Comprises four levels: Primary (sequence of amino acids), Secondary (alpha helices and beta sheets), Tertiary (three-dimensional structure), and Quaternary (multiple polypeptide chains).
- Enzymes: Catalysts for metabolic reactions.
- Lipids: Energy storage, structural (phospholipids, steroids).
- Nucleic Acids: DNA and RNA, store genetic information.

Cell: Basic unit of life containing a plasma membrane and cytoplasm with organelles.
Membranes: Selectively permeable, composed of phospholipids and proteins forming the fluid mosaic model.

Chromatin/Chromosome: DNA forms chromatin within the nucleus and condenses into chromosomes during cell division.
Cell Cycle Phases: Interphase (growth, DNA replication) and Mitosis (cell division).

Passive Transport: No energy required (e.g., diffusion, facilitated diffusion, osmosis).
Active Transport: Energy required for movement against the concentration gradient (e.g., sodium-potassium pump).
Tonicity: Effects of solutions on cell volume; isotonic, hypotonic, hypertonic.

Tissues: Groups of similar cells performing functions; classified as epithelial, connective, muscle, and nervous.

Epithelial Tissue: Covers body surfaces and lines cavities; essential for protection, absorption, and secretion.
Connective Tissue: Provides support and structure to the body, characterized by a variety of cell types and an extracellular matrix.
Muscle Tissue: Responsible for movement through contraction; encompasses three types: skeletal, cardiac, and smooth muscle.
Nervous Tissue: Composed of neurons and glial cells, critical for transmitting signals throughout the body.
Intercellular Junctions:
Tight junctions, desmosomes, gap junctions for cell interaction.

Glands: Synthesizing and secreting substances; classified as endocrine (ductless) and exocrine (with ducts).

Endocrine Glands: Ductless glands releasing hormones directly into the bloodstream, regulating various bodily functions.
Exocrine Glands: Glands with ducts that secrete substances onto epithelial surfaces or into body cavities, facilitating functions like digestion and secretion of sweat.
Methods of Secretion:
Merocrine: Release products through exocytosis without loss of cellular material.
Apocrine: Involve the loss of part of the cell's cytoplasm along with the secretory product.
Holocrine: Entire cells rupture to release their contents, as seen in sebaceous glands.

Epithelial tissues are classified based on layers and cell shape:
- By layers: Simple (one layer) vs. Stratified (multiple layers).
- By shape: Squamous (flat), Cuboidal (cube-shaped), Columnar (tall and column-like).
Microscopic Anatomy: Different types of epithelium serve various functions in protection, absorption, secretion.