Hole's Human Anatomy & Physiology - Chapter 03: Cells

Vocabulary practice flashcards covering cell structure, membrane transport, organelle function, the cell cycle, cancer mechanisms, and cellular life span from Hole's Human Anatomy & Physiology, Chapter 3.

Differentiated cell

A cell that has developed specialized structural and functional characteristics.

Composite cell

An illustrative cell model that displays the organelles and structural components commonly found across most human cell types.

Cytosol

The fluid portion of the cytoplasm in which organelles, the cytoskeleton, and biochemicals are suspended.

Cell (plasma) membrane

The flexible, selectively permeable outer boundary of a cell that maintains cell integrity and regulates the entry and exit of substances.

Signal transduction

The membrane-mediated process that permits a cell to receive and respond to incoming extracellular signals or messages.

Phospholipid bilayer

The framework of the cell membrane, consisting of outer surfaces formed by water-soluble (hydrophilic) heads and an interior formed by water-insoluble (hydrophobic) tails.

Cellular adhesion molecules (CAMs)

Membrane proteins that enable cells to stick to one another and guide migrating cells, such as white blood cells traveling toward infection sites.

Selectins

Cellular adhesion molecules that coat white blood cells to provide friction and anchor them to capillary walls.

Integrins

Cellular adhesion molecules that contact adhesion receptor proteins to direct white blood cells through capillary walls toward infection sites.

Ribosomes

Nonmembranous cytoplasmic structures composed of protein and RNA that provide enzymatic activity and structural support to assemble amino acids during protein synthesis.

Rough endoplasmic reticulum (RER)

A tubular organelle system composed of membrane-bound flattened sacs studded with ribosomes that conducts protein synthesis.

Smooth endoplasmic reticulum (SER)

A tubular network of membranous canals devoid of ribosomes that conducts lipid synthesis and sugar synthesis.

Golgi apparatus

An organelle composed of stacks of flattened membranous sacs that refines, packages, and delivers proteins synthesized on the rough endoplasmic reticulum.

Vesicles

Membranous sacs that store or transport substances into, out of, or through the cytoplasm.

Mitochondria

Membrane-bound, fluid-filled organelles that house the reactions of cellular respiration to extract energy from nutrients and generate $ATP$.

Cristae

Transverse shelf-like folds of the inner mitochondrial membrane that accommodate chemical reactions involved in cellular respiration.

Lysosomes

Membranous sacs functioning as the cellular garbage disposals, containing digestive enzymes that degrade proteins, carbohydrates, nucleic acids, bacteria, and debris.

Peroxisomes

Membranous sacs housing enzymes that break down lipids, decompose hydrogen peroxide, and detoxify alcohol.

Microfilaments

Tiny rods composed of the protein actin that have the smallest diameter among cytoskeletal elements and provide cellular movements such as muscle contraction.

Microtubules

Large hollow tubes made of the protein tubulin that form the largest diameter cytoskeletal fibers, maintaining cell shape and building cilia, flagella, and centrioles.

Intermediate filaments

Cytoskeletal structures composed of several proteins with diameters between microfilaments and microtubules that provide structural support to the nuclear envelope.

Centrosome

A nonmembranous structure near the nucleus consisting of two centrioles composed of microtubules that distribute chromosomes during cell division.

Cilia

Short, numerous, motile cellular extensions composed of microtubules that beat in coordinated strokes to move fluids such as mucus across cell surfaces.

Flagellum

A long, motile, microtubule-based projection from the cell membrane that propels an entire cell, found in humans exclusively as the tail of a sperm cell.

Microvilli

Tiny, nonmotile projections of the cell membrane composed of actin that increase the surface area available for absorption.

Inclusions

Cellular chemical deposits not necessary for cell survival, such as stored nutrients like fat or pigment granules like melanin.

Nuclear envelope

A double-layered lipid bilayer membrane surrounding the nucleus that isolates nucleoplasm from cytoplasm.

Nuclear pores

Openings in the nuclear envelope that permit specific molecules to pass between the nucleus and the cytoplasm.

Nucleolus

A dense body composed of RNA and protein within the nucleus that serves as the site of ribosome assembly.

Chromatin

Loosely coiled fibers within the nucleus composed of DNA wound around proteins that store instructions for synthesizing proteins.

Diffusion

The passive net movement of atoms, molecules, or ions from a region of higher concentration to a region of lower concentration driven by continuous thermal motion.

Facilitated diffusion

A passive transport process in which water-soluble molecules move down their concentration gradient through membrane channels or carrier proteins without using $ATP$.

Osmosis

The passive movement of water molecules across a selectively permeable membrane toward a region containing a higher concentration of impermeant solutes.

Aquaporins

Water-specific channel proteins positioned between membrane phospholipids that facilitate the passage of water during osmosis.

Osmotic pressure

The pressure generated by osmosis that is capable of lifting a volume of water, increasing as the concentration of impermeant solutes rises.

Isotonic solution

A solution that has the exact same osmotic pressure as the intracellular fluid, resulting in zero net water movement and preserved cell morphology.

Hypertonic solution

A solution containing a higher solute concentration and higher osmotic pressure than the intracellular fluid, causing cells to lose water and undergo crenation.

Hypotonic solution

A solution containing a lower solute concentration and lower osmotic pressure than intracellular fluid, causing water to enter the cell and lead to lysis.

Filtration

A passive transport process in which hydrostatic pressure forces water and small solutes through a membrane while retaining large molecules and cells.

Active transport

An energy-requiring transport mechanism that employs membrane pumps and $ATP$ hydrolysis to move particles against their concentration gradient.

Secondary active transport

A transport process in which a symport carrier protein uses the established concentration gradient of one particle to co-transport another without directly hydrolyzing $ATP$.

Endocytosis

An active mechanism that brings large particles or fluids into the cell by engulfing them within an invaginated section of membrane that pinches off as a vesicle.

Pinocytosis

A form of endocytosis in which a cell membrane indents and engulfs tiny droplets of liquid from the surrounding extracellular fluid.

Phagocytosis

A type of endocytosis during which a cell membrane engulfs solid particles, forming an internal vesicle termed a phagosome.

Receptor-mediated endocytosis

A selective endocytic process where specific extracellular ligands bind to cell-surface receptor proteins prior to vesicle formation and internal uptake.

Exocytosis

An active process in which membrane-bound secretory vesicles migrate to, fuse with, and release their contents through the cell membrane.

Transcytosis

A cellular transport route combining receptor-mediated endocytosis and exocytosis to ferry materials rapidly across a cell barrier.

Cell cycle

The orderly series of growth, replication, and division stages that a cell undergoes from the time it forms until the moment it divides.

Interphase

The active segment of the cell cycle during which a cell grows, performs normal functions, replicates its DNA, and synthesizes organelles for division.

S phase

The synthesis stage of interphase during which the cell replicates its genetic material (DNA).

Mitosis

The division of the cell nucleus (karyokinesis) that segregates duplicated chromosomes equally between two future cells.

Prophase

The initial stage of mitosis characterized by chromatin condensing into visible chromosomes, centrioles migrating to opposite poles, and the nuclear envelope dispersing.

Metaphase

The mitotic phase wherein spindle fibers attach to the centromeres of sister chromatids and align the chromosomes along the cell equator.

Anaphase

The stage of mitosis where centromeres divide and shortening spindle fibers pull newly separated individual chromosomes toward opposite centrioles.

Telophase

The final stage of mitosis during which chromosomes uncoil into chromatin, nuclear envelopes reassemble, nucleoli appear, and spindle fibers break down.

Cytokinesis

The physical division of the cytoplasm that starts during anaphase and continues through telophase to yield two daughter cells.

Cleavage furrow

The indentation formed by a contractile ring of actin microfilaments that pinches the cytoplasm in two during cytokinesis.

Telomeres

Protective noncoding DNA sequences located at the ends of chromosomes that shorten with every round of mitosis, functioning as a mitotic clock.

Contact inhibition

A regulatory mechanism ensuring that normal, healthy cells cease mitotic division when they become physically crowded.

Benign tumor

A noncancerous cellular mass that remains localized at its tissue origin and does not invade surrounding structures.

Malignant tumor

An invasive, cancerous growth capable of infiltrating neighboring tissues and spreading to remote sites in the body.

Oncogenes

Abnormal, overexpressed forms of genes that stimulate uncontrolled cell division and promote cancer formation.

Tumor suppressor genes

Normal regulatory genes that limit cell division; their inactivation or deletion lifts controls on mitosis, facilitating carcinogenesis.

Angiogenesis

The biological process of forming and extending local blood vessels, which cancer cells induce to supply themselves with nutrients.

Metastasis

The dissemination of malignant cancer cells from their primary site through blood or lymph vessels to distant anatomical areas.

Dedifferentiation

A characteristic of cancer cells marked by the loss of their specialized structural and functional attributes.

Stem cell

An undifferentiated cell that undergoes self-renewal to produce additional stem cells or divides to produce progenitor cells.

Progenitor cell

A partially differentiated, committed daughter cell originating from a stem cell that divides to yield a restricted set of specialized cell types.

Totipotent

The developmental ability of a cell, such as a fertilized egg or early blastomere, to specialize into every cell type in an organism.

Pluripotent

The developmental state of later stem cells and progenitor cells that can differentiate into a limited range of specialized cell lineages.

Apoptosis

A programmed, stepwise, genetically controlled sequence of cell death that dismantles worn-out or damaged cells without harming surrounding tissues.

Caspases

Internal cellular enzymes activated during apoptosis that systematically cleave cellular proteins and structural components.

Necrosis

Disordered, passive cell death triggered by acute injury, toxic exposure, or trauma that is distinct from programmed apoptosis.