Body Organization, Homeostasis, Basic Chemistry, and Cell Biology

Vocabulary flashcards covering anatomy subdivisions, homeostasis, directional terminology, chemical bonding, reactions, inorganic and organic biochemistry, and plasma membrane dynamics.

Anatomy

The study of the structure of body parts and their physical relationships to one another.

Physiology

The study of the function of body parts and how they work to carry out life-sustaining activities.

Principle of Complementarity of Structure and Function

The anatomical concept stating that form and function reflect one another, as the specific shape and structure of a body part determines what functions it can perform.

Gross Anatomy

A subdivision of anatomy that examines large body structures visible to the unaided or naked eye.

Cytology

The microscopic study of cells.

Histology

The microscopic study of tissues.

Embryology

A branch of developmental anatomy focused on structural and physiological developments occurring before birth.

Pathophysiology

The study of physiological processes that occur as a result of disease or injury.

Chemical Level

The simplest level of structural organization, involving atoms bonding together to form molecules with three-dimensional structures.

Metabolism

The sum of all chemical reactions occurring in body cells, consisting of catabolism (breakdown of molecules) and anabolism (synthesis of molecules).

Differentiation

The developmental process by which unspecialized cells transform into specialized cells with specific structural and functional characteristics.

Homeostasis

The dynamic state of equilibrium in which the body maintains relatively stable internal conditions despite continuous changes in the environment.

Receptor (Sensor)

A component of a homeostatic control system that monitors the environment and responds to stimuli that alter controlled variables.

Control Center

A component of homeostatic control that receives input from receptors, determines the set point at which a variable is maintained, and dictates the appropriate response.

Effector

A homeostatic control component that receives output from the control center and produces the physical response to reduce or enhance the stimulus.

Negative Feedback Mechanism

The most common feedback mechanism in the body, where the output or response shuts off or reduces the original stimulus, returning the variable toward its set point.

Positive Feedback Mechanism

A feedback mechanism in which the response exaggerates or enhances the original stimulus, causing the controlled variable to move further in the same direction.

Standard Anatomical Position

The standard reference posture in which the body is erect, feet are slightly apart, and palms face forward with thumbs pointing away from the body.

Anterior (Ventral)

Directional term describing a position toward or at the front of the body.

Posterior (Dorsal)

Directional term describing a position toward or at the back of the body.

Superior (Cranial)

Directional term describing a position above or higher than another structure, toward the top of the head.

Inferior (Caudal)

Directional term describing a position below or lower than another body part, toward the tail or lower end of the spine.

Proximal

Directional term describing a position in a limb that is nearer to its point of attachment to the body trunk.

Distal

Directional term describing a position in a limb that is farther from its point of attachment to the body trunk.

Sagittal Plane

A vertical plane dividing the body or an organ into right and left sections.

Frontal (Coronal) Plane

A vertical plane that cuts the body into anterior (front) and posterior (back) portions.

Transverse Plane

A horizontal plane that divides the body or an organ into superior (upper) and inferior (lower) portions.

Serous Membrane (Serosa)

A thin double-layered membrane lining closed ventral body cavities and covering internal organ walls, containing serous fluid to diminish friction.

Visceral Serosa

The inner layer of a serous membrane that directly adheres to and covers the external surfaces of visceral organs.

Parietal Serosa

The outer layer of a serous membrane that lines the walls of ventral body cavities.

Kinetic Energy

Energy in action or motion.

Potential Energy

Stored or inactive energy that has the capability to perform work when released.

Element

A fundamental substance that cannot be broken down into simpler substances by ordinary chemical methods.

Atomic Number

The unique integer equal to the number of protons contained within an atom's nucleus.

Mass Number

The sum of the total number of protons and neutrons located in the nucleus of an atom.

Radioisotope

An unstable isotope that decays spontaneously into a more stable atomic configuration, releasing subatomic particles and radioactivity.

Solution

A homogeneous mixture of two or more components in which solute particles are extremely small, evenly distributed, and do not settle out or scatter light.

Solvent

The dissolving medium present in the greatest quantity within a solution, typically a liquid like water.

Solute

The substance dissolved in a solvent, present in smaller quantities in a solution.

Molarity

A measure of concentration defined as the number of moles of solute dissolved per liter of solvent ($M$).

Avogadro's Number

The exact physical constant $6.02 \times 10^{23}$, representing the number of elementary entities contained in one mole of any substance.

Colloid (Emulsion)

A heterogeneous mixture containing solute particles larger than those in a solution that scatter light but do not settle out.

Suspension

A heterogeneous mixture containing large, visible solute particles that scatter light and settle to the bottom over time.

Valence Shell

An atom's outermost electron shell containing the electrons with the highest potential energy that actively participate in chemical reactions.

Octet Rule

The principle stating that atoms interact by gaining, losing, or sharing electrons to achieve a complete valence shell containing eight electrons.

Ionic Bond

A chemical bond formed by the complete transfer of valence electrons from one atom to another, producing oppositely charged ions that attract.

Cation

A positively charged ion formed when an atom gives up one or more electrons.

Anion

A negatively charged ion formed when an atom accepts one or more electrons.

Nonpolar Covalent Bond

A covalent bond formed when electrons are shared equally between two atoms, creating an electrically balanced molecule.

Polar Covalent Bond

A covalent bond formed by the unequal sharing of electrons due to differences in electronegativity, creating partial positive and negative charges across the molecule.

Hydrogen Bond

A weak attraction between an electropositive hydrogen atom of one polar molecule and an electronegative atom of another molecule.

Synthesis Reaction

An anabolic chemical reaction in which smaller atoms or molecules combine to form a larger, more complex compound.

Decomposition Reaction

A catabolic chemical reaction in which bonds are broken to decompose a larger molecule into smaller molecules or constituent elements.

Reduction-Oxidation (Redox) Reaction

An exchange reaction where electrons are transferred between reactants, causing one reactant to be oxidized (lose electrons) and another to be reduced (gain electrons).

Exergonic Reaction

A chemical reaction that yields a net release of energy, resulting in products with less potential energy than the initial reactants.

Endergonic Reaction

A chemical reaction that requires a net absorption of energy, resulting in products with higher potential energy than the reactants.

High Heat Capacity

A property of water that enables it to absorb and release large quantities of heat energy with minimal changes in its own temperature.

Electrolyte

A chemical compound (such as a salt, acid, or base) that ionizes and dissociates into free ions in water, allowing the solution to conduct electricity.

Acid

A substance that acts as a proton donor by releasing hydrogen ions ($H^+$) when dissolved in solution.

Base

A substance that acts as a proton acceptor by binding hydrogen ions ($H^+$) or releasing hydroxyl ions ($OH^-$) in solution.

pH Scale

A logarithmic measurement scale ranging from 0 to 14 that quantifies the concentration of free hydrogen ions ($[H^+]$) in a solution.

Buffer

A chemical system consisting of a weak acid and a weak base that prevents sudden, drastic shifts in pH by absorbing or releasing hydrogen ions.

Dehydration Synthesis

A chemical reaction that joins monomers into polymers by removing a molecule of water ($OH^-$ from one monomer and $H^+$ from another).

Hydrolysis

A cleavage reaction that breaks down polymers into monomer subunits by inserting a water molecule.

Monosaccharide

A single sugar molecule representing the monomer unit of carbohydrates, such as glucose, fructose, or ribose.

Disaccharide

A double sugar formed when two monosaccharides bond via dehydration synthesis, including sucrose, lactose, and maltose.

Polysaccharide

A large carbohydrate polymer composed of long chains of monosaccharides, such as starch in plants or glycogen in animals.

Triglyceride

A neutral fat lipid constructed from three fatty acid chains covalently bonded to a single glycerol backbone.

Saturated Fatty Acid

A fatty acid chain containing only single bonds between carbon atoms, allowing maximal hydrogen saturation and close packing into a solid at room temperature.

Unsaturated Fatty Acid

A fatty acid chain containing one or more double bonds between carbon atoms, producing kinks that prevent tight packing and keeping the lipid liquid at room temperature.

Phospholipid

A modified lipid featuring a polar, hydrophilic phosphate head and two nonpolar, hydrophobic fatty acid tails, forming the structural foundation of cell membranes.

Steroid

A lipid composed of four interlocking carbon rings, exemplified by cholesterol, which serves as a precursor for steroid hormones and vitamin D.

Prostaglandin

A signaling eicosanoid lipid synthesized from membrane arachidonic acid that helps regulate blood pressure, inflammation, blood clotting, and labor contractions.

Peptide Bond

A covalent bond formed through dehydration synthesis connecting the amine group of one amino acid to the carboxyl group of another.

Primary Structure

The linear sequence of amino acids linked together in a polypeptide chain.

Alpha Helix

A coiled, spring-like secondary protein structure stabilized by hydrogen bonding along the amino acid backbone.

Beta Pleated Sheet

An accordion-like folded secondary protein structure formed by hydrogen bonds between parallel polypeptide segments.

Denaturation

The process in which globular proteins uncoil and lose their functional three-dimensional shape due to physical or chemical environmental stress like heat or extremes in pH.

Enzyme

A globular protein that functions as a biological catalyst to accelerate chemical reactions without being consumed in the process.

Activation Energy

The threshold quantity of energy required to initiate a chemical reaction.

Holoenzyme

A complete, enzymatically active complex consisting of an apoenzyme (protein part) combined with its necessary cofactor or coenzyme.

Deoxyribonucleic Acid (DNA)

A double-stranded helical nucleic acid located in the cell nucleus that encodes genetic information for protein assembly.

Complementary Base-Pairing

The specific hydrogen bonding arrangement between nucleic acid bases where adenine ($A$) pairs with thymine ($T$) or uracil ($U$), and guanine ($G$) pairs with cytosine ($C$).

Ribonucleic Acid (RNA)

A single-stranded nucleic acid containing ribose sugar and uracil that translates genetic instructions from DNA to direct protein synthesis outside the nucleus.

Adenosine Triphosphate (ATP)

An adenine-containing RNA nucleotide with three phosphate groups that captures released chemical energy to directly power cellular processes.

Fluid Mosaic Model

The structural model of the plasma membrane depicting a flexible lipid bilayer embedded with floating proteins, cholesterol, and surface carbohydrates.

Integral Protein

A membrane protein firmly incorporated into the lipid bilayer, often spanning both sides as a transmembrane protein.

Glycocalyx

A carbohydrate coating on the outer plasma membrane surface composed of glycoproteins and glycolipids that facilitates cell-to-cell recognition and immune self-identification.

Tight Junction

An impermeable cell junction formed by fused transmembrane proteins that encircles cells to prevent liquid and solute movement between adjacent cells.

Desmosome

An anchoring cell junction held together by cadherin linker proteins connected to internal plaque structures and keratin filaments, distributing mechanical tension.

Gap Junction

A communicating junction formed by hollow connexon protein channels that permit ions and small molecules to flow rapidly between neighboring cells.

Simple Diffusion

The unassisted passive movement of nonpolar, lipid-soluble, or tiny molecules directly through the phospholipid bilayer down their concentration gradient.

Facilitated Diffusion

Passive transport of polar or charged molecules across the plasma membrane down their concentration gradient via carrier or channel proteins.

Aquaporin

A specialized transmembrane channel protein that selectively permits the rapid passage of water molecules across cell membranes.

Osmosis

The passive diffusion of solvent (water) across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration.

Osmotic Pressure

The inward pull or pressure driving water movement into a cell or solution due to its concentration of non-penetrating solutes.

Hydrostatic Pressure

The outward fluid pressure exerted by water against the internal walls of a cell or membrane.

Toxicity / Tonicity

The ability of an extracellular solution to modify cell volume and shape by inducing the osmotic movement of water across the plasma membrane.

Isotonic Solution

A solution possessing the exact same solute concentration as the cytoplasm, causing no net water flux and leaving cell shape unchanged.

Hypertonic Solution

A solution with a higher concentration of solutes than the cytoplasm, drawing water out of the cell and causing it to shrivel (crenation).