Human Biology: Exploring Life, Cell Structure, and Anatomical Terminology

Vocabulary flashcards covering Exploring Life and Science, Cell Structure and Function, and Anatomical Terminology, Planes, and Cavities.

Biology

The scientific study of living organisms and the environments in which they live.

Cell

The smallest structural and functional unit of an organism.

Tissue

A group of similar cells that perform a particular function.

Organ

A structure composed of several tissue types working together for a common purpose.

Organ System

A group of organs that work together for a common purpose.

Population

The members of a single species occupying a particular area.

Species

All populations of interbreeding organisms.

Community

Interacting populations of different species in a particular area.

Ecosystem

A community of populations interacting with the physical environment.

Biosphere

All of the Earth's ecosystems combined.

Energy

The capacity to do work.

Photosynthesis

The process that harvests energy from the sun and converts it into chemical energy in the form of sugars.

Metabolism

The sum of all the chemical reactions that occur within a cell or organism.

Homeostasis

The maintenance of a constant internal environment within an organism.

Reproduction

The process by which organisms pass on their genetic information to the next generation.

Growth

An increase in size and in the number of cells.

Development

All changes that occur from fertilization until death, including growth, repair, and maturation.

DNA (deoxyribonucleic acid)

The genetic information of all life that contains hereditary instructions for cellular structure and function.

Genes

Short segments of DNA that specify traits.

Mutations

Variations in genes that are usually detrimental but can sometimes be beneficial.

Evolution

How a population changes over time.

Natural Selection

The process by which evolution occurs when individuals with advantageous variations capture more resources and produce more offspring.

Adaptation

An advantageous variation that becomes more common in a population over time.

Prokaryotes

Single-celled organisms that lack a membrane-bound nucleus, found in domains Bacteria and Archaea.

Eukaryotes

Single-celled or multicellular organisms whose cells contain a membrane-bound nucleus.

Domain Archaea

A domain of prokaryotic cells adapted to extreme environments that absorb or chemosynthesize food.

Domain Bacteria

A domain of prokaryotic cells adapted to all environments that absorb, photosynthesize, or chemosynthesize food.

Domain Eukarya

The domain containing eukaryotic organisms, traditionally divided into kingdoms Plantae, Fungi, Animalia, and Protista.

Invertebrates

Animals that lack internal vertebrae for support.

Vertebrates

Animals possessing a nerve cord protected by a vertebral column.

Science

A objective way of knowing about the natural world.

Scientific Method

A standard series of logical steps used as a guideline for scientific studies.

Observation

A formal way of watching the natural world using senses, instruments, or past research.

Hypothesis

A possible, testable explanation for the observation of a natural event.

Inductive Reasoning

Using creative thinking to combine isolated facts into a cohesive whole.

Deductive Reasoning

Using 'if-then' logic to test a hypothesis and derive predictions.

Experimental Variable

The factor being studied and manipulated in an experiment.

Dependent Variable

The variable that responds to changes in the experimental variable, traditionally plotted along the y-axis.

Control Group

A test group not exposed to the experimental variable, serving as a baseline comparison.

Standard Error

A statistical value representing standard deviation that indicates the uncertainty of an experimental measurement.

Cell Theory

The biological principle stating that the cell is the basic unit of life, all living things are made of cells, and new cells arise only from preexisting cells.

Surface-Area-to-Volume Ratio

The relationship limiting cell size, where smaller cells have a larger surface area relative to volume to efficiently import nutrients and exit wastes.

Compound Light Microscope

A microscope using glass lenses and light beams to view thin, transparent specimens at magnifications up to $1{,}000\times$.

Transmission Electron Microscope (TEM)

A microscope using electron streams to project 2-D interior images at magnifications of $100{,}000\times$ or greater.

Scanning Electron Microscope (SEM)

A microscope using electron beams to produce high-magnification 3-D images of specimen surfaces.

Plasma Membrane

A selectively permeable phospholipid bilayer with attached and embedded proteins surrounding the cell cytoplasm.

Cytoplasm

The semifluid substance inside the cell containing cytosol and organelles.

Endosymbiosis

The theory that eukaryotic organelles evolved from host eukaryotic cells engulfing prokaryotic organisms.

Fluid-Mosaic Model

A plasma membrane structure model where proteins freely move laterally within a fluid phospholipid bilayer containing cholesterol.

Diffusion

The passive movement of molecules from higher to lower concentration until equilibrium is reached.

Osmosis

The diffusion of water molecules across a membrane driven by osmotic pressure.

Isotonic Solution

A solution with the same concentration of impermeable solutes as the cell, causing no change in cell size.

Hypotonic Solution

A solution with lower solute concentration than the cell, causing water to enter and cells to swell or burst (lysis).

Hypertonic Solution

A solution with higher solute concentration than the cell, causing water to leave and cells to shrink (crenation).

Facilitated Transport

Passive transport of molecules across the plasma membrane down their concentration gradient using specific protein carriers.

Active Transport

The movement of molecules against their concentration gradient (low to high) requiring ATP energy and protein pumps.

Sodium-Potassium Pump

An active transport membrane protein pump that moves sodium ions out of the cell and potassium ions into the cell using ATP.

Endocytosis

Bulk transport of molecules into the cell via invagination of the plasma membrane to form a vesicle.

Phagocytosis

A type of endocytosis involving the ingestion of solid particles into a vesicle.

Pinocytosis

A type of endocytosis involving the ingestion of fluid containing small particles.

Receptor-Mediated Endocytosis

Selective bulk transport initiated when particles bind to specific membrane receptors before vesicle formation.

Exocytosis

Bulk transport exporting molecules outside the cell via fusion of a vesicle with the plasma membrane.

Nucleus

The organelle containing DNA and genetic instructions for protein synthesis and cellular control.

Nucleolus

A dark region inside the nucleus responsible for producing ribosomes.

Nuclear Envelope

A double membrane enclosing the nucleus containing nuclear pores for molecular movement.

Ribosomes

Organelles made of rRNA and protein that serve as the sites of protein synthesis.

Endomembrane System

A series of membranous organelles (nuclear envelope, ER, Golgi apparatus, lysosomes, vesicles) processing and transporting cell materials.

Rough Endoplasmic Reticulum (RER)

A network of membranous channels studded with ribosomes used to synthesize proteins.

Smooth Endoplasmic Reticulum (SER)

A network of membranous channels lacking ribosomes that synthesizes lipids and performs diverse specialized functions.

Golgi Apparatus

Flattened membranous sacs involved in processing, packaging, modifying, and secreting lipids and proteins.

Lysosomes

Golgi-derived vesicles containing hydrolytic enzymes to break down macromolecules and cellular waste.

Cytoskeleton

A protein fiber network (microtubules, intermediate filaments, actin filaments) maintaining cell shape and facilitating organelle transport.

Cilia

Short, numerous microtubule-based exterior cell projections that move in synchronized waves to move materials.

Flagella

Long, sparse microtubule-based projections on the cell exterior that propel cells such as sperm.

Mitochondria

Double-membrane organelles with inner cristae folds and matrix that convert glucose energy into ATP via cellular respiration.

Enzymes

Reusable metabolic proteins that increase chemical reaction rates by lowering activation energy ($E_a$).

Active Site

The specific region on an enzyme where a substrate molecule binds.

Activation Energy ($E_a$)

The energy required to initiate a chemical reaction, which is reduced in the presence of an enzyme.

Anatomical Position

Standard body reference posture: standing erect, facing forward, arms at sides, palms directed forward, and toes directed forward.

Superior (Cranial or Cephalad)

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

Inferior (Caudal)

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

Ventral (Anterior)

Directional term meaning toward or at the front of the body.

Dorsal (Posterior)

Directional term meaning toward or at the backside of the body; behind.

Medial

Directional term meaning toward or at the midline of the body; on the inner side.

Lateral

Directional term meaning away from the midline of the body; on the outer side.

Proximal

Directional term meaning closer to the origin of a body part or point of attachment of a limb to the body trunk.

Distal

Directional term meaning farther from the origin of a body part or point of attachment of a limb to the body trunk.

Superficial (External)

Directional term meaning toward or at the body surface.

Deep (Internal)

Directional term meaning away from the body surface; more internal.

Sagittal Plane

Anatomical plane dividing the body vertically into right and left regions.

Midsagittal Plane

Anatomical plane dividing the body directly along the midline into equal left and right halves.

Frontal (Coronal) Plane

Anatomical plane dividing the body vertically into ventral and dorsal regions.

Transverse Plane

Anatomical plane dividing the body horizontally into superior and inferior portions.

Dorsal Body Cavity

Posterior body cavity housing the cranial cavity (brain) and spinal cavity (spinal cord).

Ventral Body Cavity

Anterior body cavity containing the thoracic cavity and abdominopelvic cavity.

Thoracic Cavity

Upper ventral cavity enclosed by ribs containing the heart and lungs, separated from the abdominopelvic cavity by the diaphragm.

Abdominopelvic Cavity

Inferior ventral cavity containing the abdominal cavity (digestive system) and pelvic cavity (reproductive and urinary systems).

Abdominal Regions

The nine anatomical divisions of the abdominopelvic cavity: right/left hypochondriac, epigastric, right/left lumbar, umbilical, right/left iliac, and hypogastric.