Human Anatomy & Physiology: Cell Biology, Body Organization, and Chemistry

Vocabulary practice flashcards covering cell structure and transport, body organization and anatomical terminology, and fundamental biological chemistry from BIO 171/BIO 197 lectures.

Cell Theory

The scientific principle stating that the cell is the structural and functional unit of life, all living organisms are composed of one or more cells, and cells arise only from pre-existing cells.

Interstitial Fluid

The extracellular fluid in which body cells are submersed or bathed.

Glycocalyx

The sugar coating on the cell surface consisting of glycolipids and glycoproteins, which functions as specific biological markers for cell-to-cell recognition.

Tight Junctions

Impermeable cell junctions formed by fused integral proteins that encircle cells to prevent fluids and most molecules from moving between them.

Desmosomes

Anchoring cell junctions formed by interlocking cadherin linker proteins anchored to internal plasma membrane plaques and reinforced by keratin filaments.

Gap Junctions

Communicating cell junctions formed by transmembrane proteins called connexons, which create passageways for ions and small molecules between adjacent cells.

Simple Diffusion

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

Facilitated Diffusion

The passive movement of water-soluble or large molecules across a cell membrane down their concentration gradient via membrane protein carriers or channels.

Osmosis

The passive diffusion of water through a selectively permeable membrane via the lipid bilayer or specialized aquaporins.

Tonicity

The ability of an extracellular solution to alter a cell's shape or internal water volume by prompting osmosis.

Primary Active Transport

A cellular transport mechanism that moves ions or small molecules against their concentration gradient using energy directly derived from ATP hydrolysis.

Transcytosis

A form of vesicular transport that moves substances sequentially into, across, and then out of a cell.

Endomembrane System

A continuous and vesicle-linked network of membranous organelles, including the rough ER and Golgi apparatus, that synthesizes, modifies, packages, and ships proteins.

Cell Cycle

The series of events a cell undergoes from formation until reproduction, divided into interphase ($G_1$, $S$, $G_2$) and the mitotic phase.

Telomeres

Protective nucleotide sequences at the ends of chromosomes that shorten with each cell division and limit cellular lifespan.

Progeria

A rare disease mimicking accelerated aging, caused by a defective progerin protein that destabilizes the nuclear lamina.

Apoptosis

Programmed cell death, a controlled process that removes unneeded, aged, or damaged cells.

Anatomy

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

Physiology

The scientific 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 core anatomical concept stating that function always reflects structure, and what a structure can do depends on its specific physical form.

Homeostasis

The state of relative internal stability maintained by dynamic equilibrium despite constant changes in the external environment.

Negative Feedback Mechanism

The primary homeostatic control mechanism in which the body's response shuts off or reduces the intensity of the original stimulus to bring a variable back to its set point.

Positive Feedback Mechanism

A control mechanism in which the initial response enhances or exaggerates the original stimulus, creating an amplifying cascade effect.

Anatomical Position

A standard body reference stance where the subject stands erect with feet slightly apart and palms facing forward with thumbs pointing away from the body.

Sagittal Plane

A vertical body plane that divides the body or an organ into right and left portions.

Frontal Plane

A vertical body plane that divides the body into anterior (front) and posterior (back) portions; also referred to as a coronal plane.

Transverse Plane

A horizontal body plane running left to right that divides the body into superior (top) and inferior (bottom) portions.

Serosa

A thin, double-layered serous membrane lining closed body cavities in the ventral trunk and covering internal organs.

Kinetic Energy

Energy in action or motion.

Potential Energy

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

Atomic Number

The number of protons contained in the nucleus of an atom, uniquely defining its chemical element.

Mass Number

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

Mixtures

Physical combinations of two or more substances categorized as solutions, colloids, or suspensions depending on solute particle size.

Molarity

A unit of concentration defined as the number of moles of solute per liter of solvent.

Avogadro's Number

The constant number of molecules contained in one mole of any substance, equal to $6.02 \times 10^{23}$.

Ionic Bond

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

Covalent Bond

A strong chemical bond formed when two atoms share pairs of valence shell electrons.

Hydrogen Bond

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

Buffer

A chemical compound or system that stabilizes fluid pH by releasing hydrogen ions when pH rises and binding hydrogen ions when pH drops.

Triglycerides

Lipid molecules composed of a glycerol backbone bound to three fatty acid chains via dehydration synthesis.

Saturated Fat

A lipid containing fatty acid chains with no double bonds between carbon atoms, allowing molecules to pack closely and form a solid at room temperature.

Denaturation

The unfolding of globular proteins causing loss of their functional three-dimensional shape, often triggered by extreme heat or decreased pH.

Activation Energy

The threshold amount of energy required to initiate a chemical reaction, which is lowered by enzymes.

Adenosine Triphosphate (ATP)

The primary energy currency molecule of the cell, composed of adenine, ribose, and three phosphate groups, which directly powers cellular work.

Cell Theory

The foundational biological principle stating that the cell is the smallest structural and functional unit of life, all organisms are made of one or more cells, and cells arise only from pre-existing cells.

Interstitial Fluid

The extracellular fluid that bathes and submerses body cells, serving as a medium for nutrient and waste exchange.

Fluid Mosaic Model

A model depicting the plasma membrane as a dynamic structure composed of a phospholipid bilayer with cholesterol, embedded proteins, and surface sugars forming a glycocalyx.

Glycocalyx

A carbohydrate-rich 'sugar coating' on the outer cell surface consisting of glycolipids and glycoproteins that acts as biological markers for cell-to-cell recognition.

Integral Proteins

Membrane proteins firmly inserted into the lipid bilayer (most being transmembrane) that possess hydrophobic and hydrophilic regions and function as channels, carriers, enzymes, or receptors.

Peripheral Proteins

Membrane proteins loosely attached to integral proteins or membrane surfaces that act as enzymes, motor proteins for shape change, or cell-to-cell links.

Tight Junctions

Impermeable cell junctions formed by the fusion of integral proteins between adjacent cells, encircling the cells to prevent fluids and molecules from passing between them.

Desmosomes

Anchoring junctions formed when linker proteins (cadherins) interlock like zipper teeth between adjacent cells, anchored internally to protein plaques and keratin filaments to prevent cell tearing.

Gap Junctions

Communicating cell junctions formed by transmembrane proteins called connexons that create hollow channels, allowing small molecules, ions, and rapid electrical signals to pass directly between cells.

Simple Diffusion

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

Facilitated Diffusion

The passive movement of water-soluble, charged, or large molecules across the plasma membrane down their concentration gradient, mediated by specific protein carriers or channels.

Osmosis

The passive diffusion of water across a selectively permeable membrane, occurring directly through the lipid bilayer or via specific water channel proteins called aquaporins.

Tonicity

The ability of an extracellular solution to alter a cell's internal water volume and shape by causing osmotic water movement across its plasma membrane.

Crenation

The shrinking of cells that occurs when placed in a hypertonic solution due to the osmotic loss of internal water.

Lysing

The swelling and bursting of cells that occurs when placed in a hypotonic solution due to the continuous osmotic influx of water.

Na+-K+ Pump

A primary active transport protein pump that expels $3\text{ Na}^+$ ions out of the cell and pumps $2\text{ K}^+$ ions into the cell using energy derived from ATP hydrolysis.

Transcytosis

A vesicular transport process in which substances are taken into a cell on one side, moved across the cytoplasm within a vesicle, and ejected on the opposite side.

Phagocytosis

A form of endocytosis known as 'cellular eating' where a cell engulfs large particles, foreign matter, or cellular debris into a membranous sac.

Pinocytosis

A form of endocytosis known as 'cellular drinking' where a cell invaginates a small droplet of extracellular fluid containing dissolved solutes into a vesicle.

Receptor-Mediated Endocytosis

A highly selective type of endocytosis where specific target extracellular molecules bind to matching cell-surface receptor proteins, triggering vesicle internalization.

Cytosol

The viscous, gel-like fluid portion of the cytoplasm consisting of water, dissolved ions, proteins, salts, and nutrients.

Inclusions

Insoluble storage substances stored within the cytoplasm that vary according to cell type, including glycogen granules, pigments, lipid droplets, and crystals.

Membranous Organelles

Internal cellular structures surrounded by a phospholipid membrane that compartmentalize metabolic reactions, including mitochondria, endoplasmic reticulum, Golgi apparatus, peroxisomes, and lysosomes.

Nonmembranous Organelles

Subcellular structures that lack a surrounding membrane, including ribosomes, cytoskeleton, centrioles, cilia, flagella, and microvilli.

Rough Endoplasmic Reticulum

An extensive membranous network studded with ribosomes that synthesizes proteins for membrane insertion, lysosomal enzymes, or cellular secretion.

Smooth Endoplasmic Reticulum

A membranous network lacking ribosomes that functions in lipid and steroid synthesis, carbohydrate metabolism, drug detoxification, and calcium storage.

Golgi Apparatus

A series of flattened membranous sacs (cisternae) that modifies, packages, and sorts proteins received from the rough ER into vesicles for secretion, membrane insertion, or lysosomes.

Lysosomes

Membranous organelles containing digestive enzymes that break down endocytosed materials, degrade damaged organelles (autophagy), and execute cell destruction after death (autolysis).

Interphase

The extended growth period of the cell cycle comprising $G_1$, $S$, and $G_2$ phases during which the cell carries out normal functions, grows, and replicates its DNA.

Mitotic Phase

The division period of the cell cycle (M phase) consisting of nuclear division (mitosis) and cytoplasmic division (cytokinesis) to produce two daughter cells.

Telomeres

Repetitive nucleotide sequences located at the ends of chromosomes that safeguard genomic integrity and progressively shorten with each cell division.

Telomerase

An enzyme capable of restoring chromosome end length; active in embryonic germ cells and cancer cells (conferring cellular immortality), but absent in most adult somatic cells.

Progeria

A rare genetic condition causing premature aging symptoms in children, caused by a mutant progerin protein that destabilizes the nuclear lamina.

Apoptosis

A controlled, energy-dependent process of programmed cell death that disposes of unneeded or damaged cells cleanly without inducing inflammation.

Anatomy

The scientific study of body structures and the physical relationships existing between various body parts.

Physiology

The scientific study of body function and how organs and systems work together to support life activities.

Principle of Complementarity of Structure and Function

The anatomical doctrine stating that function is dependent on structural form, meaning what a body part can accomplish is determined by its physical design.

Gross Anatomy

The study of large, macroscopically visible body structures without the need for magnification, encompassing regional, systemic, and surface anatomy.

Cytology

The branch of microscopic anatomy devoted to the microscopic structural study of individual cells.

Histology

The branch of microscopic anatomy devoted to the microscopic examination of biological tissues.

Embryology

A division of developmental anatomy studying developmental changes occurring in the organism before birth.

Palpation

An anatomical assessment technique that involves examining internal body structures or organs by touch and pressure with the hands.

Auscultation

An anatomical assessment technique that involves listening to sounds produced within organs (such as the heart and lungs) using a stethoscope.

Homeostasis

The state of relative internal stability maintained by dynamic physiological regulation despite changing environmental conditions.

Law of Mass Balance

The physiological principle stating that the total amount of a substance in the body remains constant if intake or metabolic production equals loss or excretion.

Negative Feedback Mechanism

A homeostatic control system where the output response decreases or reverses the original stimulus, returning the regulated variable back toward its set point.

Positive Feedback Mechanism

A physiological control system where the output response amplifies or reinforces the original stimulus, producing a cascading change away from initial baseline.

Feedforward Response

An anticipatory body response that prepares for an impending change in internal conditions before the actual change occurs.

Anatomical Position

The standard reference position where a human stands erect, facing forward, feet parallel and slightly apart, arms at sides with palms facing forward and thumbs pointing outward.

Superior

Anatomical directional term meaning toward the head end or upper part of a structure or the body; above.

Inferior

Anatomical directional term meaning away from the head end or toward the lower part of a structure or the body; below.

Anterior

Anatomical directional term meaning toward or at the front of the body; in front of (synonymous with ventral in humans).

Posterior

Anatomical directional term meaning toward or at the back of the body; behind (synonymous with dorsal in humans).

Proximal

Directional term used for limbs meaning closer to the point of origin or attachment to the body trunk.

Distal

Directional term used for limbs meaning farther from the point of origin or attachment to the body trunk.

Sagittal Plane

A longitudinal plane that runs vertically to divide the body or an organ into right and left portions.