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Anatomy & Physiology: Cellular Structure and Function

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  • What is a cell?
    The basic structural and functional unit of the human body and the smallest living unit.
  • Define cytology.
    The study of the structure and function of individual cells.
  • What is cytoplasm?
    The total fluid medium inside the cell, including organelles and cytosol.
  • What is cytosol?
    The watery component of the cytoplasm excluding organelles.
  • What is extracellular fluid (ECF)?
    The watery medium surrounding the outside of a cell that mainly serves as a transport medium.
  • Compare the chemical makeup of intracellular fluid (ICF) and extracellular fluid (ECF).
    ICF has a higher protein concentration and uses Potassium (K+) as its main cation; ECF has a lower protein concentration and uses Sodium (Na+) as its main cation.
  • What are the main functions of the plasma membrane?
    Protection, structural support, controlling substance movement in/out, cell-to-cell communication, and maintaining homeostasis.
  • Describe the phospholipid bilayer structure.
    A flexible, selectively permeable layer with hydrophilic heads facing outward and hydrophobic tails facing inward.
  • Name the main membrane lipids.
    Phospholipids, cholesterol (which stabilizes the membrane), and glycolipids.
  • What roles do membrane proteins play?
    They function in transport, act as receptors, serve as enzymes, provide structural support, and enable cell recognition.
  • What is the glycocalyx and its function?
    A carbohydrate-rich outer layer on the plasma membrane that provides protection, lubrication, and cell recognition.
  • Differentiate membranous and nonmembranous organelles.
    Membranous organelles are enclosed by phospholipid membranes; nonmembranous organelles lack membranes and are in direct contact with cytosol.
  • What is the primary function of mitochondria?
    Production of ATP (energy) via cellular respiration.
  • What is the role of the nucleus?
    Stores DNA/chromosomes and controls all cell activities.
  • Functions of rough and smooth endoplasmic reticulum (RER and SER)?
    RER synthesizes and transports proteins; SER synthesizes lipids and detoxifies toxins/drugs.
  • What does the Golgi apparatus do?
    Modifies, packages, and distributes proteins and lipids.
  • Describe lysosomes.
    Membranous organelles containing digestive enzymes for intracellular digestion and cleanup.
  • What is the function of ribosomes?
    Sites of protein synthesis.
  • Explain passive transport.
    Movement of substances down their concentration gradient without using cellular energy (ATP).
  • What is diffusion?
    The net movement of a substance from an area of high concentration to low concentration.
  • Define facilitated diffusion.
    Passive movement of substances down their concentration gradient using specialized membrane carrier proteins.
  • What is osmosis?
    The diffusion of water across a selectively permeable membrane.
  • Describe active transport.
    Movement of substances against their concentration gradient using ATP-powered membrane protein pumps.
  • What is endocytosis?
    The process of bringing bulk substances into the cell using vesicles.
  • Differentiate pinocytosis and phagocytosis.
    Pinocytosis is nonspecific uptake of extracellular fluids ('cell drinking'); phagocytosis engulfs large solid particles ('cell eating').
  • What is exocytosis?
    The fusion of an internal vesicle with the plasma membrane to release substances outside the cell.
  • Define tonicity.
    How the solute concentration of an external solution affects cell volume via osmosis.
  • Effect of isotonic solution on cells?
    Equal solute concentration inside and outside; no net water movement; cell remains normal.
  • Effect of hypotonic solution on cells?
    Lower solute concentration outside; water enters cell; cell swells and may burst (hemolysis).
  • Effect of hypertonic solution on cells?
    Higher solute concentration outside; water leaves cell; cell shrinks (crenation).
  • What is apoptosis?
    Programmed, controlled cell death (cellular suicide).
  • Compare mitosis and meiosis.
    Mitosis produces two identical somatic cells with 46 chromosomes; meiosis produces gametes with 23 chromosomes.
  • What occurs during interphase?
    Cell growth, normal metabolism, and DNA replication before division.
  • Name the four phases of mitosis.
    Prophase, Metaphase, Anaphase, Telophase.
  • What happens during cytokinesis?
    Physical division of the cytoplasm, resulting in two separate daughter cells.