Cellular Physiology & Pathophysiology – Critical/Emergency Care Nurse Course

Vocabulary flashcards summarizing essential cellular physiology, structure, communication, metabolism, adaptation, and injury concepts for exam review.

Prokaryote

Simple single-celled organism lacking a true nucleus, histones, and membrane-bound organelles; DNA resides in a nucleoid.

Eukaryote

Single- or multi-celled organism with a well-defined nucleus, histones, and membrane-bound organelles.

Cell (Plasma) Membrane

Outer boundary of the cell; thicker than internal membranes, provides protection, activation, transport, and cell-to-cell interaction.

Cytoplasm

Aqueous solution between nucleus and plasma membrane containing water, electrolytes, proteins, fats, glycogen, and all cellular organelles.

Nucleus

Central organelle that controls genetic information, DNA replication/repair, transcription, cell division, and ribosome synthesis.

Ribosome

Nucleoprotein particle (free or bound to ER) that serves as the site of protein synthesis.

Endoplasmic Reticulum (ER)

Network of tubular channels; rough ER bears ribosomes, smooth ER lacks them; specializes in synthesis and transport of proteins and lipids.

Golgi Complex

Flattened membrane stack that processes, refines, and packages proteins/lipids into secretory vesicles for intracellular or extracellular use.

Lysosome

Golgi-derived sac containing digestive enzymes that break down nutrients, debris, and harmful substances; mediates autophagy at end of cell life.

Peroxisome

Membrane-bound organelle rich in oxidative enzymes; uses oxygen to remove hydrogen, producing hydrogen peroxide during detoxification.

Mitochondrion

Double-membrane organelle responsible for cellular respiration and ATP production via oxidative phosphorylation; the cell’s “power plant.”

Cytoskeleton

Network of microtubules, microfilaments, and intermediate filaments that maintains cell shape and internal organization.

Microtubule

Rigid cytoskeletal protein that supports and moves organelles, aids nerve impulse transport, cell motility, and participates in immune/hormone responses.

Microfilament

Thin cytoskeletal fibril involved in cellular locomotion, maintenance of cell/tissue shape, and regulation of cell growth.

Protease

Enzyme that breaks down proteins; dysregulation contributes to cancer, autoimmunity, neurodegeneration; acts in several proteolytic cascades.

Proteolytic Cascade

Tightly regulated sequence of protease activations, e.g., apoptosis, blood coagulation, matrix metalloproteinase, and complement cascades.

Cellular Receptor

Protein located on membrane, in cytoplasm, or nucleus that binds specific ligands to initiate a cellular response.

Ligand

Small molecule such as a hormone, neurotransmitter, or drug that specifically binds to a cellular receptor.

Contact-Dependent Signaling

Form of cell communication requiring direct membrane-to-membrane contact between cells.

Hormonal Signaling

Endocrine cells release hormones into bloodstream to act on distant target cells.

Paracrine Signaling

Cells secrete local chemical mediators that act mainly on nearby cells.

Autocrine Signaling

Cell releases a chemical that binds to receptors on its own surface to influence its own activity.

Synaptic Signaling

Neurons release neurotransmitters across synapses to stimulate adjacent nerve or muscle cells.

Neurohormonal Signaling

Neurosecretory neurons release hormones into blood to act on distant targets.

Adenosine Triphosphate (ATP)

Primary energy currency of the cell, generated mainly in mitochondria and used to power cellular functions.

Anaerobic Respiration

Cytoplasmic metabolism (glycolysis) that produces 2 ATP without oxygen.

Aerobic Respiration

Oxygen-dependent metabolism involving citric acid cycle and oxidative phosphorylation, yielding ~32 ATP.

Passive Transport

Movement of substances down a concentration gradient across membranes without energy expenditure (e.g., diffusion, osmosis).

Active Transport

Energy-requiring movement of substances against a concentration gradient across membranes.

Mediated Transport

Membrane transport that requires a specific carrier or channel; can be passive or active.

Sodium-Potassium Pump

Active transporter that moves 3 Na⁺ out of and 2 K⁺ into the cell using ATP, maintaining membrane potential.

Depolarization

Opening of sodium channels that makes membrane potential less negative, initiating action potentials.

Repolarization

Restoration of negative resting membrane potential via sodium channel closure and potassium efflux.

Hyperpolarization

Temporary membrane potential increase beyond resting level, making cell less excitable; corresponds to refractory periods.

Growth Factor (Cytokine)

Peptide signal that regulates cell growth, proliferation, and development (e.g., PDGF).

Platelet-Derived Growth Factor (PDGF)

Growth factor that stimulates proliferation of connective tissue cells and neuroglia.

Atrophy

Decrease in cell size leading to reduced tissue or organ size.

Hypertrophy

Increase in individual cell size resulting in enlarged organ; often a pathologic adaptation.

Hyperplasia

Increase in cell number due to elevated rate of cellular division.

Metaplasia

Reversible replacement of one mature cell type by another, often less differentiated, cell type.

Dysplasia

Abnormal change in size, shape, and organization of mature cells; may be precancerous.

Hypoxic Injury

Cellular damage from oxygen deprivation causing ATP depletion, ion pump failure, and eventual cell swelling or death.

Free Radical Injury

Damage initiated by unstable molecules with unpaired electrons, leading to difficult-to-control chain reactions.

Apoptosis

Programmed, orderly cell death characterized by cell shrinkage and non-inflammatory phagocytosis of cell remnants.

Necrosis

Uncontrolled cell death with membrane rupture, organelle swelling, and inflammation.

Cellular Senescence

State in which cells permanently stop dividing, contributing to aging and tissue dysfunction.

Telomere Attrition

Progressive shortening of chromosomal end caps during replication, associated with aging.

Osmosis

Movement of water across a selectively permeable membrane from an area of higher water concentration (lower solute) to an area of lower water concentration (higher solute).

Endocytosis

Process by which cells ingest external material by engulfing it with their cell membrane, forming a vesicle.

Exocytosis

Process by which cells release substances from inside the cell to the outside by fusing a vesicle with the cell membrane.

Chromatin

Complex of DNA and proteins (histones) packed into a highly condensed structure within the cell nucleus.

Extracellular Matrix (ECM)

Network of secreted macromolecules (proteins and polysaccharides) that provides structural and biochemical support to surrounding cells.