Cell & Tissue Characteristics CH. 2

Vocabulary flashcards covering key terms and concepts from Chapter 2 (Cell & Tissue Characteristics) including cell organelles, membrane transport, chemical signaling, cellular metabolism, membrane potentials, and primary tissue types.

Pathology

The study of structural alterations in cells, tissues, and organs that help identify the cause of disease.

Pathogenesis

The pattern of tissue changes associated with the development of disease.

Etiology

The study of the causes of disease or injury.

Idiopathic

Describing a disease or condition that has no identifiable cause.

Iatrogenic

Describing a disease or injury that occurs as a direct result of medical intervention.

Clinical Manifestations

The objective signs and subjective symptoms associated with a disease or injury.

Eukaryotic Cells

Complex cells that contain membrane-bound organelles, a well-defined nucleus, and several chromosomes (e.g., animals, plants, single-celled fungi, protozoa, most algae).

Prokaryotic Cells

Simple cells that lack membrane-bound organelles, a nuclear membrane, and a distinct nucleus, possessing a single chromosome (e.g., bacteria, rickettsiae).

Metabolic Absorption

The cellular function in which cells take in and utilize nutrients and other substances from their surroundings.

Nucleus

A double-membrane organelle that controls cell division, stores genetic information, and manages DNA replication, repair, and transcription.

Nucleolus

A dense structure within the nucleus composed of RNA, DNA, and histones where ribosomal RNA synthesis occurs.

Histones

DNA-binding proteins in the nucleus that assist in DNA folding and genome structure.

Cytosol

The aqueous solution portion of the cytoplasm in which cellular organelles are suspended.

Endoplasmic Reticulum

A membrane network responsible for synthesizing and transporting protein and lipid components, consisting of smooth and rough (ribosome-bound) regions.

Ribosomes

RNA-protein complexes that serve as the primary sites of cellular protein synthesis.

Golgi Complex

An organelle that processes, packages, and directs the transport of proteins within the cell.

Lysosomes

Sac-like organelles originating from the Golgi complex that contain over $40$ digestive enzymes (hydrolases) to break down proteins, lipids, nucleic acids, and carbohydrates.

Peroxisomes

Sac-like organelles containing oxidative enzymes (such as catalase and urate oxidase) that utilize $O_2$ to produce $H_2O_2$, break down fatty acids, and synthesize phospholipids for myelin.

Mitochondria

Double-membrane organelles containing cristae that are responsible for cellular respiration, oxidative phosphorylation, and energy (ATP) production.

Vaults

Octagonal cytoplasmic organelles that encapsulate proteins and may transport messenger RNA from the nucleus to ribosomes.

Cytoskeleton

A structural network composed of microfilaments, intermediate filaments, and microtubules that maintains cell shape and internal organization.

Centrioles

Cytoskeletal structures consisting of $9$ bundles of $3$ microtubules each that participate in chromosome division during cell reproduction.

Caveolae

Dimpled invaginations of the plasma membrane involved in vesicular transport and cellular signaling.

Amphipathic

Describing a molecule that contains both hydrophilic (water-loving, polar) and hydrophobic (water-hating, nonpolar) regions, such as cell membrane phospholipids.

Extracellular Matrix (ECM)

A meshwork of fibrous proteins embedded in a gel-like carbohydrate substance that regulates cell growth, movement, and differentiation.

Collagen

A fibrous macromolecule in the extracellular matrix that provides structural strength to tissues.

Elastin

A rubber-like protein macromolecule in the extracellular matrix that enables tissues to stretch and recoil.

Fibronectin

An adhesive glycoprotein in the extracellular matrix that functions to hold cells in place.

Basement Membrane

A thin, flexible layer of extracellular matrix lying beneath epithelial cells and surrounding muscle, fat, and Schwann cells.

Desmosomes

Cell junctions that mechanically hold adjacent cells together as adhering junctions.

Tight Junctions

Impermeable cell junctions that seal cells together to prevent molecules from leaking between them.

Gap Junctions

Clusters of communicating tunnels called connexons that allow small ions and molecules to pass directly between adjacent cells.

Cell Adhesion Molecules (CAMs)

Cell surface proteins (integrins, cadherins, selectins, and Ig superfamily) that bind a cell to adjacent cells or the extracellular matrix.

Paracrine Signaling

A form of cellular communication where cells secrete local chemical mediators that influence neighboring target cells.

Autocrine Signaling

A form of cellular communication where a cell secretes a messenger that binds to receptors on its own plasma membrane.

Hormonal Signaling

A mode of communication where specialized endocrine cells secrete hormones into the blood to act on distant target cells.

Neurohormonal Signaling

Chemical communication where neurosecretory neurons secrete neurohormones directly into the bloodstream.

Signal Transduction

The pathway through which an extracellular messenger (first messenger) binds a plasma membrane receptor to activate intracellular cascades (second messengers like cAMP or $Ca^{2+}$).

Anabolism

The energy-using metabolic process of synthesizing larger molecules from smaller subunits.

Catabolism

The energy-releasing metabolic process of breaking down larger molecules into smaller ones.

Adenosine Triphosphate (ATP)

The primary energy store and transfer molecule of the cell, utilized for organic synthesis, active transport, and muscle contraction.

Glycolysis

An anaerobic metabolic process in the cytoplasm that breaks down glucose into pyruvate, yielding ATP and NADH.

Citric Acid Cycle

A mitochondrial pathway that oxidizes acetyl CoA to produce NADH, ATP, and waste products ($CO_2$, $H_2O$).

Oxidative Phosphorylation

The mitochondrial mechanism by which energy produced from catabolism is transferred to ATP via electron transport.

Passive Transport

The movement of water and uncharged molecules across a plasma membrane down a concentration gradient without requiring cellular energy.

Active Transport

The movement of solute molecules against or up a concentration gradient requiring cellular energy (ATP).

Hydrostatic Pressure

The mechanical pushing force exerted by water against a cellular membrane or vessel wall.

Oncotic Pressure

The colloid osmotic pulling pressure exerted by plasma proteins that tends to draw water into the circulatory system.

Osmosis

The movement of water across a semipermeable membrane from an area of higher water concentration to lower water concentration.

Osmolality

A measure of solute concentration expressed as milliosmoles per kilogram of solvent ($mOsm/kg$), normally $280\text{--}294 formulation mOsm/kg$ in body fluids.

Osmolarity

A measure of solute concentration defined as the number of milliosmoles per liter of solution ($mOsm/L$).

Uniport

A mediated transport mechanism that moves a single solute molecule across the membrane in one direction.

Symport

A mediated transport mechanism that simultaneously moves two different solute molecules across the membrane in the same direction.

Antiport

A mediated transport mechanism that simultaneously moves two different solute molecules across the membrane in opposite directions.

Endocytosis

A vesicular transport process where the plasma membrane invaginates to enclose external macromolecules into vesicles.

Phagocytosis

A type of endocytosis involving the cellular ingestion of large solid particles such as bacteria or debris.

Pinocytosis

A type of endocytosis involving the ingestion of fluids and small solute particles.

Exocytosis

The release of cellular substances from intracellular vesicles into the extracellular space.

Tonicity

The effective osmolality of a solution relative to intracellular fluid.

Isotonic Solution

A solution that has the same osmolality or concentration of particles ($285 formulation mOsm/kg$) as intracellular or extracellular fluid.

Hypotonic Solution

A solution with a lower solute concentration than cellular fluid, causing water to move into cells and swell.

Hypertonic Solution

A solution with a higher solute concentration ($>285\text{--}294 formulation mOsm/kg$) than cellular fluid, causing water to leave cells and shrink.

Resting Membrane Potential

The steady electrical voltage across the membrane of an unstimulated cell, where the interior is negatively charged relative to the exterior.

Action Potential

A rapid change in resting membrane potential that occurs when a nerve or muscle cell receives a stimulus exceeding threshold.

Depolarization

The decrease in membrane potential toward zero or positive charge caused by the influx of $Na^+$ ions into the cell.

Threshold Potential

The critical membrane voltage required for a cell to continue depolarizing and generate an action potential without further stimulation.

Repolarization

The restoration of negative resting membrane potential primarily driven by outward $K^+$ diffusion.

Absolute Refractory Period

The period during an action potential when the plasma membrane cannot respond to any additional stimulus regardless of strength.

Relative Refractory Period

The phase late in an action potential when permeability to $K^+$ increases and only a stronger-than-normal stimulus can trigger a new action potential.

Mitosis

The process of cell division in somatic cells that produces two genetically identical daughter cells.

Cytokinesis

The division of the cytoplasm that follows nuclear division during cell reproduction.

Growth Factors

Peptide signaling molecules (cytokines) that transmit signals between cells to regulate growth and cellular proliferation.

Stem Cells

Undifferentiated cells capable of self-renewal and multipotency that give rise to specialized cell types.

Epithelial Tissue

A primary tissue type covering internal and external body surfaces that functions in protection, absorption, secretion, and excretion.

Connective Tissue

A primary tissue type characterized by abundant extracellular matrix that provides structural binding, support, and organ framework.

Muscle Tissue

A contractile primary tissue composed of myocytes (smooth, skeletal, or cardiac) that enables voluntary and involuntary body movements.

Neural Tissue

A primary tissue type composed of neurons and synapses specialized for rapidly receiving and transmitting electrical impulses.