A&P 1 & 2

A&P Glossary

Every term used across all A&P 1 and A&P 2 songs, defined and alphabetized. Search it, or jump by letter.

271 terms

A B C D E F G H I J K L M N O P R S T U V Z

A

Abdominopelvic regions/quadrants: Nine regions (e.g., epigastric, umbilical, hypogastric) or four quadrants (RUQ, LUQ, RLQ, LLQ).Unit 1 — Foundations, Organization & Terminology
ABO / Rh blood groups: Antigen-based classification for transfusion compatibility.Unit 11 — Blood
Absorption: Uptake of nutrients into blood/lymph.Unit 16 — Digestive System
Accessory organs: Salivary glands, liver, gallbladder, pancreas.Unit 16 — Digestive System
Accommodation: Change in lens shape (via ciliary muscle) to focus on near versus distant objects.Unit 9 — Peripheral & Autonomic Nervous System; Senses
Acetylcholinesterase: Enzyme in the synaptic cleft that breaks down acetylcholine, ending stimulation so the muscle fiber can relax.Unit 7 — Muscular System
Acid-base balance: Regulation of blood pH by lungs, kidneys, and buffers.Unit 18 — Urinary System & Fluid/Electrolyte Balance
Acidosis / alkalosis (respiratory vs. metabolic): Blood pH below 7.35 (acidosis) or above 7.45 (alkalosis). Respiratory forms arise from altered CO2 (ventilation); metabolic forms arise from changes in HCO3- or fixed acids. The lungs and kidneys provide compensation.Unit 18 — Urinary System & Fluid/Electrolyte Balance
Action potential: All-or-none depolarization/repolarization wave; involves voltage-gated Na+ and K+ channels.Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Active transport: Movement against a gradient requiring ATP (e.g., sodium-potassium pump).Unit 3 — Cells & Cellular Physiology
Adaptive (specific) immunity: Targeted response with memory.Unit 14 — Lymphatic System & Immunity
Afterload: Pressure the ventricle must overcome to eject blood (largely arterial pressure); higher afterload reduces stroke volume.Unit 12 — Cardiovascular System: Heart
Agonist / antagonist / synergist: Prime mover / opposer / assister.Unit 7 — Muscular System
Aldosterone: Promotes Na+ reabsorption and K+ secretion.Unit 18 — Urinary System & Fluid/Electrolyte Balance
Alimentary canal (GI tract): Mouth -> pharynx -> esophagus -> stomach -> small intestine -> large intestine -> anus.Unit 16 — Digestive System
Alveolus: Site of gas exchange in the lungs.Unit 15 — Respiratory System
Anatomical position: Standard reference posture: body erect, feet parallel, arms at sides, palms and face forward.Unit 1 — Foundations, Organization & Terminology
Anatomy: The study of the structure of body parts and their relationships to one another.Unit 1 — Foundations, Organization & Terminology
Anemia / leukemia / thrombus: Low RBC/hemoglobin / WBC cancer / stationary clot.Unit 11 — Blood
Antagonistic hormones: Pairs with opposing effects (e.g., insulin/glucagon, PTH/calcitonin).Unit 10 — Endocrine System (often bridges A&P I and II)
Antibody (immunoglobulin): Protein produced by plasma cells that binds antigen.Unit 14 — Lymphatic System & Immunity
Antidiuretic hormone (ADH): Promotes water reabsorption.Unit 18 — Urinary System & Fluid/Electrolyte Balance
Antigen: Substance triggering an immune response.Unit 14 — Lymphatic System & Immunity
Apoptosis: Programmed cell death; an orderly, regulated self-destruction used in development and tissue turnover, distinct from necrosis (uncontrolled death from injury).Unit 3 — Cells & Cellular Physiology
Appendicular skeleton: Limbs and girdles (pectoral, pelvic).Unit 6 — Skeletal System
Artery: Carries blood away from the heart; thick, elastic walls.Unit 13 — Cardiovascular System: Vessels & Circulation
Atherosclerosis / hypertension: Arterial plaque / chronic high blood pressure.Unit 13 — Cardiovascular System: Vessels & Circulation
Atom: Smallest unit of an element retaining its properties; contains protons, neutrons, electrons.Unit 2 — Chemistry & Biochemistry Basics
ATP (adenosine triphosphate): The cell's primary energy currency.Unit 2 — Chemistry & Biochemistry Basics
Atrioventricular (AV) valves: Tricuspid (right) and mitral/bicuspid (left).Unit 12 — Cardiovascular System: Heart
Autonomic nervous system (ANS): Involuntary control of smooth/cardiac muscle and glands.Unit 9 — Peripheral & Autonomic Nervous System; Senses
Axial skeleton: Skull, vertebral column, thoracic cage.Unit 6 — Skeletal System

B

B lymphocyte: Mediates humoral (antibody) immunity.Unit 14 — Lymphatic System & Immunity
Baroreceptor reflex: Regulates blood pressure via pressure sensors.Unit 13 — Cardiovascular System: Vessels & Circulation
Basal metabolic rate (BMR): Energy used at rest.Unit 17 — Metabolism & Nutrition
Basement membrane: Layer anchoring epithelium to underlying connective tissue.Unit 4 — Tissues (Histology)
Bicarbonate transport: Major form of CO2 carriage in blood.Unit 15 — Respiratory System
Bile: Emulsifies fats; produced by liver, stored in gallbladder.Unit 16 — Digestive System
Blood: Fluid connective tissue; plasma plus formed elements.Unit 11 — Blood
Blood pressure: Force of blood on vessel walls; systolic/diastolic.Unit 13 — Cardiovascular System: Vessels & Circulation
Body cavities: Dorsal (cranial + vertebral) and ventral (thoracic + abdominopelvic); the thoracic cavity contains the pleural, pericardial, and mediastinal spaces.Unit 1 — Foundations, Organization & Terminology
Body planes: Sagittal (divides left/right), midsagittal (median), frontal (coronal; anterior/posterior), transverse (horizontal; superior/inferior).Unit 1 — Foundations, Organization & Terminology
Bone markings: Surface features of bones: projections (process, tuberosity, condyle, trochanter, spine), depressions (fossa), and openings (foramen, meatus, sinus); used for muscle attachment and passage of vessels/nerves.Unit 6 — Skeletal System
Bone remodeling: Continuous resorption and deposition; regulated by PTH and calcitonin.Unit 6 — Skeletal System
Boyle's law: At constant temperature, gas pressure varies inversely with volume; enlarging the thoracic cavity lowers intrapulmonary pressure so air flows in, and vice versa.Unit 15 — Respiratory System
Brainstem: Midbrain, pons, medulla oblongata; controls vital functions.Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Buffer: Substance that resists pH change (e.g., bicarbonate buffer system).Unit 2 — Chemistry & Biochemistry Basics

C

Calcium homeostasis: Regulation of blood Ca2+ by bone (reservoir), the kidneys, and the intestines; PTH raises blood calcium (stimulating osteoclasts and renal reabsorption), while calcitonin lowers it. Bone serves as the body's major calcium store.Unit 6 — Skeletal System
Capillary: Site of exchange between blood and tissues.Unit 13 — Cardiovascular System: Vessels & Circulation
Capillary exchange (Starling forces): Movement of fluid across capillary walls governed by the balance of hydrostatic pressure (pushes fluid out) and blood colloid osmotic pressure (pulls fluid in); net filtration at the arterial end and net reabsorption at the venous end, with excess drained by lymphatics.Unit 13 — Cardiovascular System: Vessels & Circulation
Carbohydrate: Sugar/starch used mainly for energy; monosaccharides, disaccharides, polysaccharides.Unit 2 — Chemistry & Biochemistry Basics
Cardiac conduction system: SA node → AV node → bundle of His → Purkinje fibers.Unit 12 — Cardiovascular System: Heart
Cardiac cycle: Systole (contraction) and diastole (relaxation).Unit 12 — Cardiovascular System: Heart
Cardiac output (CO): Blood pumped per minute; CO = heart rate x stroke volume.Unit 12 — Cardiovascular System: Heart
Cell cycle: Interphase (G1, S, G2) and mitotic (M) phase.Unit 3 — Cells & Cellular Physiology
Cellular respiration: Glycolysis, Krebs cycle, electron transport chain producing ATP.Unit 17 — Metabolism & Nutrition
Central nervous system (CNS): Brain and spinal cord.Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Cerebellum: Coordinates movement and balance.Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Cerebrospinal fluid (CSF): Cushions and nourishes CNS.Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Cerebrum: Largest brain region; cortex governs higher functions; divided into frontal, parietal, temporal, occipital lobes.Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Chambers: Two atria (receiving) and two ventricles (pumping).Unit 12 — Cardiovascular System: Heart
Cleavage: Rapid mitotic divisions of the zygote without growth, producing progressively smaller cells (blastomeres) and forming the blastocyst.Unit 20 — Development & Heredity
Coagulation: Clotting cascade forming fibrin.Unit 11 — Blood
Cochlea: Auditory portion of the inner ear.Unit 9 — Peripheral & Autonomic Nervous System; Senses
Compact vs. spongy bone: Dense outer bone vs. trabecular inner bone.Unit 6 — Skeletal System
Compliance: Distensibility of the lungs and chest wall—how readily they expand for a given pressure change; reduced by fibrosis or surfactant deficiency.Unit 15 — Respiratory System
Concentration gradient: Difference in solute concentration between two regions; the driving force for diffusion and the energy stored for facilitated and active transport.Unit 3 — Cells & Cellular Physiology
Connective tissue: Most abundant/diverse tissue; cells in extracellular matrix; includes loose (areolar, adipose, reticular), dense (regular, irregular), cartilage, bone, and blood.Unit 4 — Tissues (Histology)
Control center (integrator): Determines the set point and directs the appropriate response (often the brain or an endocrine gland).Unit 1 — Foundations, Organization & Terminology
Cortisol: Adrenal glucocorticoid; stress and metabolism.Unit 10 — Endocrine System (often bridges A&P I and II)
Covalent bond: Bond formed by sharing electrons; polar (unequal sharing) or nonpolar (equal sharing).Unit 2 — Chemistry & Biochemistry Basics
Creatine phosphate: High-energy molecule that rapidly regenerates ATP from ADP during the first seconds of intense muscle activity.Unit 7 — Muscular System
Cytoplasm / cytosol: Intracellular fluid and its suspended organelles.Unit 3 — Cells & Cellular Physiology
Cytoskeleton: Microfilaments, intermediate filaments, microtubules providing shape and movement.Unit 3 — Cells & Cellular Physiology

D

Depolarization / repolarization / hyperpolarization: Membrane becoming less negative / returning to rest / more negative than rest.Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Dermis: Connective tissue layer (papillary + reticular) containing vessels, nerves, glands.Unit 5 — Integumentary System
Diaphragm: Primary muscle of inspiration.Unit 15 — Respiratory System
Diaphysis / epiphysis: Shaft / ends of a long bone.Unit 6 — Skeletal System
Diencephalon: Thalamus (relay) and hypothalamus (homeostatic control).Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Diffusion: Passive movement of substances from high to low concentration.Unit 3 — Cells & Cellular Physiology
Directional terms: Superior/inferior, anterior (ventral)/posterior (dorsal), medial/lateral, proximal/distal, superficial/deep.Unit 1 — Foundations, Organization & Terminology
DNA replication: Semiconservative copying of DNA before cell division; each strand serves as a template, producing two identical double helices (helicase, DNA polymerase, ligase).Unit 3 — Cells & Cellular Physiology
Dominant / recessive: Allele expression patterns.Unit 20 — Development & Heredity

E

Edema: Excess fluid accumulation in the interstitial space, from increased capillary hydrostatic pressure, decreased plasma proteins, or impaired lymphatic drainage.Unit 18 — Urinary System & Fluid/Electrolyte Balance
Effector: Structure that carries out the response to restore homeostasis.Unit 1 — Foundations, Organization & Terminology
Electrocardiogram (ECG/EKG): Record of electrical activity (P wave, QRS complex, T wave).Unit 12 — Cardiovascular System: Heart
Electrolyte: Substance that dissociates into ions in solution and conducts electricity (e.g., Na+, K+, Ca2+).Unit 2 — Chemistry & Biochemistry Basics
Electron transport chain: Uses O2 as final electron acceptor to produce most ATP via oxidative phosphorylation.Unit 17 — Metabolism & Nutrition
Element: Substance composed of one type of atom (e.g., C, H, O, N).Unit 2 — Chemistry & Biochemistry Basics
Endocrine gland: Ductless gland secreting hormones (e.g., pituitary, thyroid, adrenal, pancreas).Unit 10 — Endocrine System (often bridges A&P I and II)
Endocytosis / exocytosis: Bulk transport into (phagocytosis, pinocytosis) or out of the cell.Unit 3 — Cells & Cellular Physiology
Endoplasmic reticulum: Rough ER (protein synthesis) and smooth ER (lipid synthesis, detoxification, Ca2+ storage).Unit 3 — Cells & Cellular Physiology
Enzyme: Biological catalyst (usually protein) that lowers activation energy.Unit 2 — Chemistry & Biochemistry Basics
Enzymes: Amylase (carbs), pepsin/proteases (proteins), lipase (fats).Unit 16 — Digestive System
Epidermis: Outermost keratinized stratified squamous epithelium; layers (deep to superficial): basale, spinosum, granulosum, lucidum, corneum.Unit 5 — Integumentary System
Epinephrine / norepinephrine: Adrenal medulla catecholamines that reinforce and prolong the sympathetic "fight-or-flight" response.Unit 10 — Endocrine System (often bridges A&P I and II)
Epiphyseal plate: Growth plate of long bones.Unit 6 — Skeletal System
Epithelial tissue: Covers surfaces and lines cavities; classified by layers (simple/stratified) and shape (squamous, cuboidal, columnar); avascular.Unit 4 — Tissues (Histology)
Erythrocyte (RBC): Carries oxygen via hemoglobin; anucleate, biconcave.Unit 11 — Blood
Essential nutrients: Substances the body cannot synthesize (certain amino acids, fatty acids, vitamins, minerals).Unit 17 — Metabolism & Nutrition
Excitation-contraction coupling: Sequence linking action potential to contraction via Ca2+.Unit 7 — Muscular System
Extracellular matrix: Ground substance plus fibers (collagen, elastic, reticular).Unit 4 — Tissues (Histology)

F

Facilitated diffusion: Passive transport via membrane proteins.Unit 3 — Cells & Cellular Physiology
Fertilization: Fusion of sperm and egg forming a zygote.Unit 19 — Reproductive System
First-/second-/third-degree burn: Classification by depth of tissue damage.Unit 5 — Integumentary System
Fluid compartments: Intracellular and extracellular (interstitial + plasma) fluid.Unit 18 — Urinary System & Fluid/Electrolyte Balance
Fracture: Break in bone; types include simple, compound, comminuted, greenstick.Unit 6 — Skeletal System
Frank-Starling mechanism: Intrinsic property by which increased venous return (preload) stretches cardiac muscle and increases the force of contraction, matching output to inflow.Unit 12 — Cardiovascular System: Heart

G

Gametogenesis: Spermatogenesis (sperm) and oogenesis (ova) via meiosis.Unit 19 — Reproductive System
Gastrulation: Early embryonic reorganization that establishes the three primary germ layers.Unit 20 — Development & Heredity
Gene / allele: Unit of heredity / alternate form of a gene.Unit 20 — Development & Heredity
Genotype / phenotype: Genetic makeup / observable traits.Unit 20 — Development & Heredity
Germ layers (ectoderm / mesoderm / endoderm): The three primary tissue layers: ectoderm (skin, nervous system), mesoderm (muscle, bone, blood, kidneys), and endoderm (gut and respiratory linings, associated glands).Unit 20 — Development & Heredity
Gestation: Pregnancy period; three trimesters.Unit 20 — Development & Heredity
Gland: Endocrine (ductless, secretes into blood) or exocrine (secretes via ducts).Unit 4 — Tissues (Histology)
Glomerular filtration rate (GFR): Volume of filtrate formed per minute.Unit 18 — Urinary System & Fluid/Electrolyte Balance
Glomerulus: Capillary tuft where filtration occurs.Unit 18 — Urinary System & Fluid/Electrolyte Balance
Glycogenesis / glycogenolysis / gluconeogenesis: Glycogen synthesis / breakdown / glucose synthesis from noncarbohydrates.Unit 17 — Metabolism & Nutrition
Glycolysis: Glucose split to pyruvate in cytoplasm; nets 2 ATP.Unit 17 — Metabolism & Nutrition
Golgi apparatus: Modifies, packages, and ships proteins/lipids.Unit 3 — Cells & Cellular Physiology
Gonads: Testes (male) and ovaries (female); produce gametes and hormones.Unit 19 — Reproductive System
Graded potential: Small, variable-strength local change in membrane potential that decays with distance; can summate to reach threshold.Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Gray vs. white matter: Gray matter contains neuron cell bodies and unmyelinated fibers; white matter contains myelinated axon tracts.Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Gross (macroscopic) anatomy: Study of structures visible to the naked eye (e.g., organs, muscles, bones).Unit 1 — Foundations, Organization & Terminology
Growth hormone (GH): Anterior pituitary hormone that stimulates growth, protein synthesis, and fat mobilization; acts partly via IGF-1 from the liver.Unit 10 — Endocrine System (often bridges A&P I and II)
Gustation: Sense of taste; taste-bud chemoreceptors detect five qualities (sweet, sour, salty, bitter, umami).Unit 9 — Peripheral & Autonomic Nervous System; Senses

H

Hematopoiesis: Blood cell formation in red bone marrow.Unit 11 — Blood
Hemoglobin: Iron-containing protein binding O2 and CO2.Unit 11 — Blood
Hemostasis: Stoppage of bleeding: vascular spasm, platelet plug, coagulation.Unit 11 — Blood
Homeostasis: The maintenance of a relatively stable internal environment despite continuous external and internal changes; the central organizing principle of physiology.Unit 1 — Foundations, Organization & Terminology
Homozygous / heterozygous: Identical / different alleles for a gene.Unit 20 — Development & Heredity
Hormone: Chemical messenger secreted into blood, acting on distant target cells.Unit 10 — Endocrine System (often bridges A&P I and II)
Hydrogen bond: Weak attraction between a partially positive hydrogen and an electronegative atom; important in water and protein/DNA structure.Unit 2 — Chemistry & Biochemistry Basics
Hypodermis (subcutaneous layer): Fat and areolar tissue beneath skin; not part of skin proper.Unit 5 — Integumentary System
Hypothalamic-pituitary axis: Hypothalamus controls anterior/posterior pituitary, which regulates other glands.Unit 10 — Endocrine System (often bridges A&P I and II)

I

Inflammation: Redness, heat, swelling, pain in response to injury.Unit 14 — Lymphatic System & Immunity
Innate (nonspecific) immunity: Immediate, general defenses (barriers, phagocytes, inflammation, fever).Unit 14 — Lymphatic System & Immunity
Insulin / glucagon: Lower / raise blood glucose (pancreatic islets).Unit 10 — Endocrine System (often bridges A&P I and II)
Ion: Charged atom; cation (positive) or anion (negative).Unit 2 — Chemistry & Biochemistry Basics
Ionic bond: Bond formed by transfer of electrons and electrostatic attraction between ions.Unit 2 — Chemistry & Biochemistry Basics
Isotonic vs. isometric contraction: Muscle changes length vs. tension without length change.Unit 7 — Muscular System

J

Joint (articulation): Fibrous (immovable), cartilaginous (slightly movable), synovial (freely movable).Unit 6 — Skeletal System

K

Keratinocyte: Predominant epidermal cell producing keratin.Unit 5 — Integumentary System
Kidney: Filters blood, forms urine, regulates fluid/electrolyte and acid-base balance.Unit 18 — Urinary System & Fluid/Electrolyte Balance
Krebs (citric acid) cycle: Oxidizes acetyl-CoA, generating NADH/FADH2 and CO2.Unit 17 — Metabolism & Nutrition

L

Leukocyte (WBC): Immune cells; granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes).Unit 11 — Blood
Levels of structural organization: Chemical → cellular → tissue → organ → organ system → organismal.Unit 1 — Foundations, Organization & Terminology
Lipid: Nonpolar molecule; includes triglycerides, phospholipids, steroids.Unit 2 — Chemistry & Biochemistry Basics
Liver functions: Metabolism, detoxification, bile production, nutrient storage.Unit 16 — Digestive System
Lymph: Fluid within lymphatic vessels.Unit 14 — Lymphatic System & Immunity
Lymph node: Filters lymph; site of immune activation.Unit 14 — Lymphatic System & Immunity
Lymphatic system: Vessels and organs returning fluid to blood and supporting immunity.Unit 14 — Lymphatic System & Immunity
Lysosome: Contains digestive enzymes for intracellular breakdown.Unit 3 — Cells & Cellular Physiology

M

Major electrolytes: Ions critical to fluid balance and excitable-tissue function: Na+ (extracellular volume/osmolarity), K+ (resting membrane potential), Ca2+ (muscle/nerve function, clotting), and Cl-/HCO3- (acid-base).Unit 18 — Urinary System & Fluid/Electrolyte Balance
Mechanical vs. chemical digestion: Physical breakdown vs. enzymatic breakdown.Unit 16 — Digestive System
Meiosis: Cell division producing haploid gametes with genetic variation.Unit 19 — Reproductive System
Melanocyte: Produces melanin pigment for UV protection.Unit 5 — Integumentary System
Membrane potential: Voltage difference across the plasma membrane; resting potential ~ −70 mV in neurons.Unit 3 — Cells & Cellular Physiology
Membranes: Cutaneous (skin), mucous, serous, synovial.Unit 4 — Tissues (Histology)
Meninges: Dura mater, arachnoid mater, pia mater.Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Menstrual cycle: Ovarian and uterine cycles regulated by FSH, LH, estrogen, progesterone.Unit 19 — Reproductive System
Metabolism: Sum of all chemical reactions in the body; includes catabolism (breakdown) and anabolism (synthesis).Unit 1 — Foundations, Organization & Terminology
Microscopic anatomy: Study of structures too small to see without magnification; includes cytology (cells) and histology (tissues).Unit 1 — Foundations, Organization & Terminology
Mitochondrion: Site of aerobic ATP production (cellular respiration).Unit 3 — Cells & Cellular Physiology
Mitosis: Nuclear division producing two identical diploid daughter cells (prophase, metaphase, anaphase, telophase).Unit 3 — Cells & Cellular Physiology
Motor unit: One motor neuron and all fibers it innervates.Unit 7 — Muscular System
Muscle fatigue: Decline in ability to contract, from factors such as ATP depletion, ion imbalances, and lactic acid accumulation.Unit 7 — Muscular System
Muscle metabolism (aerobic vs. anaerobic): ATP for contraction comes from aerobic respiration (efficient, requires O2) and anaerobic glycolysis (fast, produces lactic acid). Oxygen debt (excess post-exercise oxygen consumption) is the extra O2 needed afterward to restore creatine phosphate, ATP, and clear lactic acid.Unit 7 — Muscular System
Muscle tissue: Skeletal (voluntary, striated), cardiac (involuntary, striated, intercalated discs), smooth (involuntary, non-striated).Unit 4 — Tissues (Histology)
Myelin sheath: Insulating layer speeding conduction; formed by oligodendrocytes (CNS) and Schwann cells (PNS).Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Myocardium: Cardiac muscle layer of the heart wall.Unit 12 — Cardiovascular System: Heart
Myofibril: Contractile organelle containing actin (thin) and myosin (thick) filaments.Unit 7 — Muscular System

N

Negative feedback: A control mechanism in which the response reverses or reduces the original stimulus, returning the variable toward the set point (e.g., body temperature regulation). The predominant homeostatic mechanism.Unit 1 — Foundations, Organization & Terminology
Nephron: Functional unit of the kidney.Unit 18 — Urinary System & Fluid/Electrolyte Balance
Nerve / tract: Bundle of axons in the PNS (nerve) or CNS (tract).Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Nervous tissue: Neurons (signaling) and neuroglia (support).Unit 4 — Tissues (Histology)
Neuroglia: Supporting cells (astrocytes, oligodendrocytes, microglia, ependymal, Schwann cells, satellite cells).Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Neuromuscular junction: Synapse between motor neuron and muscle fiber; uses acetylcholine.Unit 7 — Muscular System
Neuron: Excitable cell transmitting electrical signals; has dendrites, soma (cell body), axon.Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Neurotransmitter: Chemical messenger (e.g., acetylcholine, dopamine, serotonin, GABA, glutamate).Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Nucleic acid: DNA and RNA; store and express genetic information.Unit 2 — Chemistry & Biochemistry Basics
Nucleus: Control center containing DNA.Unit 3 — Cells & Cellular Physiology

O

Olfaction: Sense of smell; olfactory chemoreceptors in the nasal epithelium detect airborne odorant molecules.Unit 9 — Peripheral & Autonomic Nervous System; Senses
Organelle: Specialized intracellular structure (e.g., mitochondria, ribosomes).Unit 3 — Cells & Cellular Physiology
Origin / insertion: Fixed attachment / movable attachment of a muscle.Unit 7 — Muscular System
Osmolarity / osmolality: Concentration of solute particles per liter of solution (osmolarity) or per kilogram of water (osmolality); determines water movement between compartments.Unit 18 — Urinary System & Fluid/Electrolyte Balance
Osmosis: Passive diffusion of water across a selectively permeable membrane.Unit 3 — Cells & Cellular Physiology
Ossification: Bone formation; intramembranous and endochondral.Unit 6 — Skeletal System
Osteoblast / osteocyte / osteoclast: Bone-forming / mature bone / bone-resorbing cells.Unit 6 — Skeletal System
Osteology: Study of bones.Unit 6 — Skeletal System
Osteon (Haversian system): Structural unit of compact bone.Unit 6 — Skeletal System
Ovulation: Release of an oocyte from the ovary.Unit 19 — Reproductive System
Oxyhemoglobin dissociation curve: Relationship between O2 saturation and partial pressure; Bohr effect shifts it.Unit 15 — Respiratory System

P

Parasympathetic division: "Rest-and-digest"; craniosacral.Unit 9 — Peripheral & Autonomic Nervous System; Senses
Parathyroid hormone (PTH) / calcitonin: PTH (parathyroid glands) raises blood Ca2+; calcitonin (thyroid C cells) lowers it — the primary antagonistic pair in calcium homeostasis.Unit 10 — Endocrine System (often bridges A&P I and II)
Partial pressure: Pressure of an individual gas; drives O2 and CO2 diffusion.Unit 15 — Respiratory System
Pericardium: Membrane sac surrounding the heart.Unit 12 — Cardiovascular System: Heart
Peripheral nervous system (PNS): Nerves and ganglia outside the CNS; includes cranial and spinal nerves.Unit 9 — Peripheral & Autonomic Nervous System; Senses
Peripheral resistance: Opposition to blood flow, mainly from arterioles.Unit 13 — Cardiovascular System: Vessels & Circulation
Peristalsis: Wave-like smooth muscle contractions moving contents.Unit 16 — Digestive System
pH: Measure of hydrogen ion concentration; scale 0–14, with 7 neutral; blood pH normally ~7.35–7.45.Unit 2 — Chemistry & Biochemistry Basics
Pharynx / larynx / trachea / bronchi: Conducting airways.Unit 15 — Respiratory System
Physiology: The study of the function of body parts and how they work to sustain life.Unit 1 — Foundations, Organization & Terminology
Placenta: Temporary organ of exchange between maternal and fetal blood for nutrients, gases, and wastes; also secretes pregnancy hormones.Unit 20 — Development & Heredity
Plasma: Liquid matrix (~55%); water, proteins (albumin, globulins, fibrinogen), electrolytes.Unit 11 — Blood
Plasma membrane: Phospholipid bilayer with proteins; selectively permeable boundary of the cell (fluid mosaic model).Unit 3 — Cells & Cellular Physiology
Platelet (thrombocyte): Cell fragment essential for clotting.Unit 11 — Blood
Pleura: Serous membrane surrounding the lungs.Unit 15 — Respiratory System
Positive feedback: A control mechanism in which the response amplifies the original stimulus, driving the variable further from baseline (e.g., childbirth, blood clotting).Unit 1 — Foundations, Organization & Terminology
Posterior pituitary hormones (ADH / oxytocin): Hormones synthesized in the hypothalamus and released from the posterior pituitary; ADH promotes renal water reabsorption, and oxytocin drives uterine contraction and milk ejection (a positive-feedback example).Unit 10 — Endocrine System (often bridges A&P I and II)
Preload: Degree of ventricular stretch at the end of diastole (end-diastolic volume); greater preload increases stroke volume.Unit 12 — Cardiovascular System: Heart
Protein: Polymer of amino acids; functions in structure, enzymes, transport, contraction.Unit 2 — Chemistry & Biochemistry Basics
Pulmonary circuit / systemic circuit: Heart-to-lungs / heart-to-body loops.Unit 12 — Cardiovascular System: Heart

R

Receptor (sensor): Structure that detects a change (stimulus) in a controlled variable.Unit 1 — Foundations, Organization & Terminology
Reflex arc: Receptor → sensory neuron → integration center → motor neuron → effector.Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Refractory period: Interval after an action potential when a neuron cannot (absolute) or can only with a stronger stimulus (relative) fire again; ensures one-way propagation and limits firing frequency.Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Renal tubule: Proximal convoluted tubule, loop of Henle, distal convoluted tubule, collecting duct.Unit 18 — Urinary System & Fluid/Electrolyte Balance
Renin-angiotensin-aldosterone system (RAAS): Regulates blood pressure and fluid balance.Unit 18 — Urinary System & Fluid/Electrolyte Balance
Respiration: Includes pulmonary ventilation, external respiration, gas transport, internal respiration.Unit 15 — Respiratory System
Respiratory control centers: Medullary (ventral and dorsal respiratory groups) and pontine centers that set the rhythm and depth of breathing, modulated by chemoreceptors sensing CO2, H+, and O2.Unit 15 — Respiratory System
Resting membrane potential: Charge separation across a resting neuron's membrane (~ −70 mV).Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Retina / rods / cones: Photoreceptive layer; dim-light vs. color vision.Unit 9 — Peripheral & Autonomic Nervous System; Senses
Ribosome: Site of protein synthesis.Unit 3 — Cells & Cellular Physiology

S

SA node: Pacemaker of the heart.Unit 12 — Cardiovascular System: Heart
Saltatory conduction: Rapid impulse jumping between nodes of Ranvier on myelinated axons.Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Sarcomere: Contractile unit between two Z discs.Unit 7 — Muscular System
Sarcoplasmic reticulum: Stores and releases Ca2+.Unit 7 — Muscular System
Sebaceous gland: Secretes oily sebum.Unit 5 — Integumentary System
Selective permeability: Property of the plasma membrane allowing some substances to cross while restricting others; basis of controlled transport and membrane potential.Unit 3 — Cells & Cellular Physiology
Semilunar valves: Pulmonary and aortic valves.Unit 12 — Cardiovascular System: Heart
Sensory receptor types: Mechanoreceptors, thermoreceptors, photoreceptors, chemoreceptors, nociceptors (pain).Unit 9 — Peripheral & Autonomic Nervous System; Senses
Serous membranes: Parietal (lines cavity wall) and visceral (covers organ) layers; include pleura, pericardium, peritoneum.Unit 1 — Foundations, Organization & Terminology
Set point: The physiological value around which a regulated variable is maintained.Unit 1 — Foundations, Organization & Terminology
Sex-linked inheritance: Inheritance of genes on the sex chromosomes (typically X-linked); X-linked recessive traits (e.g., hemophilia, red-green color blindness) are expressed more often in males, who have a single X.Unit 20 — Development & Heredity
Skeletal muscle fiber: Multinucleated striated cell; contracts for movement.Unit 7 — Muscular System
Sliding filament theory: Contraction occurs as thin filaments slide over thick filaments, shortening sarcomeres.Unit 7 — Muscular System
Sodium-potassium pump (Na+/K+-ATPase): Active transporter that moves 3 Na+ out and 2 K+ in per ATP, maintaining the ion gradients that establish the resting membrane potential.Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Somatic nervous system: Voluntary control of skeletal muscle.Unit 9 — Peripheral & Autonomic Nervous System; Senses
Special senses: Vision, hearing, equilibrium, taste, smell.Unit 9 — Peripheral & Autonomic Nervous System; Senses
Spleen / thymus / tonsils: Lymphoid organs.Unit 14 — Lymphatic System & Immunity
Steroid vs. peptide hormone: Lipid-soluble (intracellular receptors, alter gene expression) vs. water-soluble (surface receptors, second messengers like cAMP).Unit 10 — Endocrine System (often bridges A&P I and II)
Stroke volume: Blood ejected per beat.Unit 12 — Cardiovascular System: Heart
Sudoriferous (sweat) gland: Eccrine (thermoregulation) and apocrine.Unit 5 — Integumentary System
Summation (temporal / spatial): Adding of graded potentials over time (temporal) or from multiple inputs at once (spatial) to reach threshold.Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Surfactant: Lipoprotein secreted by alveolar type II cells that lowers surface tension, preventing alveolar collapse and easing lung expansion.Unit 15 — Respiratory System
Sympathetic division: "Fight-or-flight"; thoracolumbar.Unit 9 — Peripheral & Autonomic Nervous System; Senses
Synapse: Junction between neurons; chemical synapses use neurotransmitters.Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Synovial joint: Contains joint cavity, synovial fluid, articular cartilage; includes hinge, ball-and-socket, pivot, etc.Unit 6 — Skeletal System
Systolic / diastolic pressure: Pressure during ventricular contraction / relaxation.Unit 13 — Cardiovascular System: Vessels & Circulation

T

T lymphocyte: Mediates cell-mediated immunity; helper (CD4) and cytotoxic (CD8) types.Unit 14 — Lymphatic System & Immunity
Target cell: Cell with receptors for a specific hormone.Unit 10 — Endocrine System (often bridges A&P I and II)
Testosterone / estrogen / progesterone: Primary sex hormones.Unit 19 — Reproductive System
Threshold: The critical membrane voltage (typically ~ −55 mV) at which voltage-gated Na+ channels open and an all-or-none action potential is triggered.Unit 8 — Nervous System (Fundamentals & Central Nervous System)
Thyroid hormone (T3/T4): Regulates metabolic rate.Unit 10 — Endocrine System (often bridges A&P I and II)
Tidal volume / vital capacity / residual volume: Lung volumes and capacities.Unit 15 — Respiratory System
Tissue: Group of similar cells performing a common function; four primary types.Unit 4 — Tissues (Histology)
Tonicity: Isotonic (no net movement), hypotonic (cell swells), hypertonic (cell shrinks).Unit 3 — Cells & Cellular Physiology
Transcription: Synthesis of messenger RNA from a DNA template by RNA polymerase in the nucleus; the first step of gene expression.Unit 3 — Cells & Cellular Physiology
Translation: Synthesis of a polypeptide at the ribosome, where tRNA anticodons read mRNA codons to assemble amino acids in sequence.Unit 3 — Cells & Cellular Physiology
Troponin / tropomyosin: Regulatory proteins of the thin filament; tropomyosin blocks myosin-binding sites at rest, and Ca2+ binding to troponin shifts tropomyosin to expose those sites, permitting cross-bridge formation.Unit 7 — Muscular System
Tubular reabsorption / secretion: Return of substances to blood / addition of substances to filtrate.Unit 18 — Urinary System & Fluid/Electrolyte Balance
Twitch / tetanus / recruitment: Single contraction / sustained contraction / activation of more motor units.Unit 7 — Muscular System

U

Up-regulation / down-regulation: Increase or decrease in the number of target-cell receptors, altering tissue sensitivity to a hormone. # PART TWO — ANATOMY & PHYSIOLOGY IIUnit 10 — Endocrine System (often bridges A&P I and II)

V

Vaccination / immunological memory: Induced protection via memory cells.Unit 14 — Lymphatic System & Immunity
Vasoconstriction / vasodilation: Narrowing / widening of vessels.Unit 13 — Cardiovascular System: Vessels & Circulation
Vein: Carries blood toward the heart; has valves.Unit 13 — Cardiovascular System: Vessels & Circulation
Venous return: Volume of blood returning to the heart; a key determinant of preload, aided by the skeletal-muscle pump, respiratory pump, and venous valves.Unit 12 — Cardiovascular System: Heart
Ventilation (breathing): Inspiration and expiration driven by pressure gradients (Boyle's law).Unit 15 — Respiratory System
Vestibular apparatus: Inner-ear structures (semicircular canals and otolith organs—utricle and saccule) that detect rotational and linear head movement for equilibrium.Unit 9 — Peripheral & Autonomic Nervous System; Senses
Villi / microvilli: Increase absorptive surface of small intestine.Unit 16 — Digestive System

Z

Zygote / embryo / fetus: Sequential stages of prenatal development.Unit 20 — Development & Heredity

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