1. Cells and the Nervous System

Neuron: the cells that transmit signals throughout the body.

Nerve: a bundle of neurons and support cells.

Axon: a long string-like structure that extends off the cell body of the neuron to transfer signals over distance.

Dendrite: a tentacle-like structure that receives signals from other neurons.

Cell body / soma: the main part of the neuron where the nucleus is located.

Synapse: The space between neurons where signals pass from one neuron to the next.

Neural circuit: a group of neurons that work together to perform a function.

Neurotransmitter: a chemical messenger that allows for neurons to communicate.

Receptor: a protein on the outside of a cell that receives signals and then triggers a reaction.

Synaptic vesicle: a bubble at the end of axons that stores, carries, and delivers neurotransmitters.

Axonal transport: a process where proteins, fats, and organelles are moved across the axon.

Synaptic dysfunction: impaired communication between neurons.

Synaptic loss: loss of communication between neurons.

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Motor neuron: neurons that tell your body to move.

Sensory neuron: neurons that carry sensory information, including touch and pain.

Dopaminergic neuron: neurons that synthesize and release the neurotransmitter dopamine.

Glial cell: Cells that support neuronal function, but do not carry signals.

Astrocyte: A type of glial cell that provide energy and structure to neurons.

Microglia: a cell type that lives in the central nervous system (brain and spinal cord) and looks for tissue damage and infection, then clears it.

Oligodendrocyte: a glial cell located in the central nervous system (brain, spinal cord) that forms a protective insulation layer around axons

Schwann cell: a glial cell located in the peripheral nervous system that forms a protective insulation layer around axons

Myelin: a fatty layer that surrounds axons, which allows electrical signals to travel faster

Demyelination: the loss or damage of myelin that results in the slow-down or stop of electrical signaling.

Remyelination: the process where new myelin forms around axons in areas where it was damaged

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Central nervous system: Consists of the brain and spinal cord and works as the body’s command center.

Peripheral nervous system: The nerves outside of the brain and spinal cord that connect to the rest of the body.

Brainstem: the part of the brain that connects to the spinal cord and is in control of automatic functions like heartbeat and breathing.

Spinal cord: the main nerve in the body that carries signals between the brain and body.

Cortex: outer layer of the brain that is responsible for higher level thinking.

Motor cortex: the part of your brain that plans and controls motor function.

Frontal lobe: The part of your brain that is responsible for decision making, planning, and personality.

Hippocampus: The part of the brain that is responsible for forming memories.

Basal ganglia: A group of brain structures that are responsible for movement.

Striatum: A part of the basal ganglia that is responsible for coordinating voluntary movement, reward processing, and habit formation.

Substantia nigra: A part of the basal ganglia that is responsible for involuntary movement, producing dopamine (reward response), and addiction.

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Cell: The building block of living things.

Organelle: A structure within the cell that has a specific job to help keep the cell running.

Mitochondria: An organelle that produces energy for the cell in the form of ATP.

Lysosome: An organelle that functions as the cell’s recycling plant by breaking down, disposing, and reusing waste.

Golgi apparatus: An organelle that packages and sends products (ex. Proteins) where they need to go.

Endoplasmic reticulum / ER: An organelle with a tube-like structure that makes and transports proteins, fats and carbohydrates.

Nucleus: The “brain” of the cell, where DNA is located, that tells the cell how to function.

Cytoplasm: The “jelly” that the organelles sit in.

Cell membrane: The wall on the outside of the cell that manages what can come in and out of the cell.

Vesicle: A bubble that carries things from one side of the cell to the other or in/out of the cell.

Autophagosome: a vesicle that engulfs and then transports material within the cell to lysosomes to be broken down.

Cytoskeleton: a network of protein strands that help shape and support the cell.

Microtubules: Provides both structure and a “railway” system within the cell that helps to transport things.
 

2. Genes and Inheritance

Gene: A section of DNA that contains instructions to make a protein.

DNA: The instruction manual for your body.

RNA: A working copy of the DNA that is used to build things like proteins.

Protein: A molecule composed of amino acids and built based on instructions from DNA that are the primary building blocks of the body and are important for body function and structure.

Central dogma: A theory that states DNA is transcribed into RNA, and RNA is translated into protein.

Transcription: The step where DNA code is copied into RNA.

Translation: The step where RNA is built into protein.

RNA processing: Modifications that are made to raw RNA strands, that transform them into a mature, functional template to be translated into protein.

RNA splicing: A step during RNA processing when non-coding regions (introns) are removed and coding regions (exons) are joined together.

RNA-binding protein: a protein that binds to RNA and facilitates its transportation, stability, and translation.

Expression: The process when a genes code is activated to produce its corresponding functional protein.

Upregulation: An increase in cellular production rate of a specific RNA or protein.

Downregulation: A decrease in cellular production rate of a specific RNA or protein.

Isoform: any of several different structural variations of a protein derived from the same gene.

Enzyme: a type of protein that speeds up chemical reactions in the body.

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Mutation: a permanent change in the original DNA sequence.

Variant: A difference or change in a DNA sequence compared to a standard reference sequence

Pathogenic Variant: A specific change in a DNA sequence that is known to directly cause a disease.

Risk Variant: A DNA change that increases an individual's statistical likelihood or susceptibility to developing a disease but does not directly cause the condition on its own.

Causal mutation: A specific DNA change that directly leads to the development of a trait or disease.

Allele: One of two or more alternative versions of a specific gene.

Genotype: An individual’s complete set of genes or specific combination of alleles.

Phenotype: The observable physical traits, features, or clinical symptoms resulting from a specific genotype.

Genetic risk: The statistical probability of developing a condition based on a person's genetic makeup.

Familial disease: a genetic disease that is passed down from family members.

Sporadic disease: a disease that happens by chance or environmental causes.

Repeat expansion: a mutation where a short piece of DNA sequence is repeated too many times.

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Inheritance: The passing down of genetic information and traits from parent to offspring.

Autosomal dominant: An inheritance pattern where possessing a single mutated gene copy (on a non-sex chromosome) can cause a condition.

Autosomal recessive: An inheritance pattern that requires two mutated copies of a gene (one from each parent) to cause a condition.

X-linked inheritance: A pattern of inheritance for gene mutations that is linked to the X chromosome.

Carrier: An individual holding one mutated copy of a gene for a recessive trait; they usually do not show symptoms but can pass it on.

Penetrance: The percentage of individuals carrying a specific gene variant who display symptoms of the disease.

Variable expressivity: Variations in the severity or range of symptoms among individuals sharing the exact same genetic mutation.

Genetic testing: Medical analysis of DNA or RNA to identify genetic variants associated with disease.

Mutation effect terms

Loss of function: A mutation that reduces or eliminates the normal expression or activity of a protein.

Gain of function: A mutation that increases the normal expression or activity of a protein.

Toxic gain of function: A mutation where the altered protein acquires a new ability that directly damages cells.

Haploinsufficiency: A state where having only one functional copy of a gene does not produce enough protein for normal function.

Dominant negative effect: A scenario where a mutated protein actively interferes with the function of the normal protein made by the second copy.

Protein misfolding: An error where a protein fails to fold into its correct functional 3D shape.

 

3. Cellular Mechanisms

Trafficking: The directed movement of proteins or vesicles to specific locations within a cell.

Localization: the specific region or compartment within a cell where a molecule is positioned.

Transport: the controlled movement of substances across cellular membranes or along cellular structures.

Signaling: the chemical communication system cells use to respond to internal and external environments.

Cleavage: the breakdown of proteins or RNA into smaller pieces by enzymes.

Secretion: the release of substances (like hormones or neurotransmitters) from a cell.

Uptake: the process of a cell taking in nutrients or molecules from its outside environment.

Clearance: The removal of waste, toxins, or damaged proteins from a cell or tissue.

Degradation: The breakdown of complex cellular structures into simpler components.

Activation: The process of turning on a biological pathway, enzyme, or protein.

Inhibition: The process of inactivating a biological pathway or protein.

Regulation: The precise control and balance of cellular processes to maintain normal function.

Propagation: The process where misfolded proteins force nearby healthy proteins to misfold and clump together into toxic clumps.

Degeneration: The progressive loss of function or structure in cells or tissues.

Dysfunction: The impaired functioning of organelles, cells, or organs.

Repair: The restoration of damaged cellular components or genetic sequences to normal function.

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Metabolism: The total sum of chemical reactions in a cell that convert nutrients into energy and biological materials.

Energy production: The conversion of nutrients, such as glucose, into usable cellular energy.

ATP: adenosine triphosphate, the primary source of energy for cells.

Oxidative phosphorylation: The main metabolic pathway inside mitochondria that uses oxygen to produce large amounts of ATP.

Electron transport chain: A series of protein complexes inside the mitochondria that move electrons to produce energy needed to make ATP.

Glycolysis: The preliminary pathway that breaks glucose down without oxygen to produce energy and pyruvate.

Mitochondrial respiration: The oxygen-dependent process inside mitochondria that converts pyruvate into ATP.

Cellular stress: Significant disruptions to a cell’s environment that impact its normal function or survival.

Reactive oxygen species / ROS: Highly reactive, oxygen-containing molecules that can damage cellular proteins, lipids, and DNA that are a biproduct of cellular metabolism.

Free radical: An unstable atom or molecule with an unpaired electron that damages surrounding cellular components.

Oxidative stress: An imbalance where harmful free radicals outnumber protective antioxidants, leading to cellular damage.

Antioxidant defense: Cellular enzymes and molecules that block free radicals (ROS) from causing damage to cells.

Calcium homeostasis: The tight cellular regulation of calcium concentration levels required for healthy signaling and function. For example, mitochondria use calcium to control how cells live, work, and communicate. However, when this calcium balance breaks down, it forces the cell to destroy itself, which can lead to serious conditions like Alzheimer's disease.

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Proteostasis: The balance of cellular mechanisms regulating proteins being made, folded, transported, and degraded.

Autophagy: The process by which cells are broken down, and their proteins and organelles are recycled to maintain intracellular homeostasis.

Lysosomal degradation: The breakdown of waste products and damaged molecules inside lysosomes using acidic enzymes.

Vacuolization: the formation of vacuoles, or fluid filled sacs as a defense mechanism against stress, a method for recycling waste or can indicate cell death.

Phagocytosis: The process in which a phagocyte, a type of white blood cell, surrounds and destroys foreign substances and then removes the dead cells.

Ubiquitin-proteasome system: A system where misfolded and damaged proteins are tagged with ubiquitin and then shredded into smaller pieces to be recycled.

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Inflammation: The biological tissue response to injury, infection, or irritation, characterized by immune activation.

Immune activation: The initiation of immune cell defenses in response to perceived damage, pathogens, or cellular stress.

Cytokine: A small signaling protein that is secreted by cells and regulates immune responses and activation.

Chemokine: A specific type of cytokine that directs the movement and recruitment of immune cells to sites of damage

Inflammasome: a group of proteins inside of cells that triggers inflammation and cell death in response to danger signals.

DNA damage: Alterations or breaks in the chemical structure of DNA that interfere with normal gene function.

Cell death: The permanent end to all biological systems that support a cell.

Apoptosis: A programmed pathway of cell death that safely eliminates damages or unneeded cells.

Senescence: A zombie-like state where damaged cells stop dividing but remain metabolically active.

Senescence-associated secretory phenotype / SASP: A state senescent cells adopt where they release more inflammatory factors, which affects neighboring cells.

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Axon degeneration: The self-destructive breakdown and death of axons.

Golgi fragmentation: The structural breakdown and disorganization of the Golgi apparatus during cellular stress.

Lysosomal dysfunction: Impairment of the lysosome's ability to properly degrade and recycle cellular waste.

Mitophagy: The selective autophagic removal and recycling of damaged or unhealthy mitochondria to prevent the release of harmful ROS.

Mitochondrial quality control: The cellular monitoring system that repairs, degrades, or replaces damaged mitochondria.

SARM1 activation: The turning on of the SARM1 enzyme, which triggers rapid axonal degeneration following injury or stress.

Synaptic pruning: The natural regulatory process of dismantling weak or unused synaptic connections between neurons.
 

4. Disease Pathology

Neurodegeneration: The progressive loss of structure, function, or death of neurons in the nervous system.

Pathology: The structural and functional abnormalities that characterize a disease.

Disease progression: The ongoing and worsening of a disease over time.

Disease modification: treatments or interventions that target the underlying cause of illness to slow, stop, or reverse its progression.

Symptomatic treatment: Therapies designed to relieve or manage clinical symptoms.

Biomarker: A measurable biological indicator used to detect disease presence, track progression, or assess treatment response.

Lesion: A region of damaged, altered, or abnormal tissue resulting from disease or physical trauma.

Relapse: The return or sudden worsening of disease symptoms after a period of improvement.

Remission: A temporary or permanent reduction in the severity of disease symptoms.

Progressive disease: A medical condition that steadily worsens over time.

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Excitotoxicity: neuronal death or damage due to the excessive release neurotransmitters that excite neurons, such as glutamate.

Ischemia: A medical condition associated with the loss or restriction of blood flow to tissues.

Infarct: An area of dead tissue caused by the lack of blood flow to the affected tissue or organ.

Secondary injury: Delayed damage to cells, tissues, or organs that occurs hours to weeks after the initial injury.

Chronic traumatic encephalopathy / CTE: A progressive neurodegenerative brain disorder linked to repeated head injuries.

Demyelinating lesion: An area of damage where the protective myelin sheath that covers axons has degraded.

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Bradykinesia: The slowness of movement and decreased ability to perform voluntary movements.

Rigidity: Involuntary stiffness and resistance to passive movement in muscles.

Tremor: An involuntary and rhythmic movement, that causes shaking, often in the hands.

Dyskinesia: Involuntary and erratic muscle movements that are often uncontrollable and can be caused from long-term use of dopamine-blocking medications.

Dystonia: A movement disorder characterized by involuntary, sustained muscle contractions that cause twisting or abnormal postures.

Gait: A person’s unique style of walking.

Balance impairment: Reduced stability or ability to maintain equilibrium while sitting, standing, or walking.

Ataxia: A group of neurological disorders that cause a lack of voluntary muscle control and coordination.

Spasticity: Abnormally tight or stiff muscles caused by hyperactive muscle stretch reflexes.

Weakness: A reduction in the physical force or power exerted by one or more muscles.

Cognitive decline: A progressive loss of mental abilities, such as memory, executive function, and spatial awareness

Dementia: A general term for loss of memory, thinking, and behavior that decline over time.

Mild cognitive impairment / MCI: A condition where people have more memory and thinking impairments compared to others in their age group.

Aphasia: A disorder that is caused by damage to the language center of the brain that impairs reading, writing, speaking, or understanding language

Executive function: Higher-level cognitive abilities used to plan, focus, organize, solve problems, and manage time.

Behavioral symptoms: Changes in personality, mood, agitation, or conduct caused by neurological conditions.

Anosmia: The loss of smell.

Dysphagia: A condition characterized by difficulty with swallowing.

Neuropathy: Disease or damage affecting peripheral nerves, often leading to pain, tingling, or weakness.

Peripheral neuropathy: Damage to the nerve network outside the brain and spinal cord, commonly causing numbing, tingling, and burning sensations often in the hands and feet.

Motor symptoms: Physical health signs affecting movement, such as tremors, stiffness, slowness of movement or loss of balance.

Autonomic function: A part of the peripheral nervous system that regulates automatic functions like heart rate, respiration, blood pressure, digestion, and sexual arousal.

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5. Treatments and Clinical Trials 

Intervention: any drug, therapy, or procedure implemented to modify health outcome or treat a disease.

Standard of care: The accepted baseline treatment guidelines considered appropriate and effective by medical professionals.

Small molecule: A low-molecular-weight chemical compound that easily enters cells to interact with target molecules.

Monoclonal antibody: A laboratory-engineered protein designed to target specific disease proteins or cells in the body.

Antisense oligonucleotide / ASO: A short, synthetic strand of genetic material engineered to bind and alter specific RNA molecules.

Gene therapy: A medical technique that introduces, alters, or replaces genetic material within cells to treat disease

AAV / adeno-associated virus: A harmless virus that is engineered and then used as a delivery vehicle in gene therapy.

Enzyme inhibitor: A molecule that binds to an enzyme and decreases or blocks its activity.

Immunotherapy: Treatments designed to enhance, suppress, or redirect the immune system to fight disease.

Thrombectomy: A surgical procedure to physically remove a blood clot from an obstructed blood vessel.

Lifestyle intervention: Modifications to daily habits, such as exercise, diet, and sleep to prevent or manage disease.
 

Clinical trial: A research study in human volunteers that tests the safety and effectiveness of new medical interventions.

Randomized controlled trial (RCT): A study where participants are randomly assigned to receive either the new treatment or the control treatment.

Placebo: An inactive, dummy intervention used in clinical trials to compare against the real treatment.

Control group: A baseline group in a trial that receives a placebo or standard treatment for comparison against the test group.

Double-blind: A study in which neither the researcher nor the patients know who is receiving placebo or the real treatment.

Observational study: A study where researchers observe outcomes in participants without manipulating variables or treatments.

Cohort study: An observational trial that tracks a specific group of individuals over time to assess health outcomes.

Preclinical study: Experimental research conducted in cell cultures or animal models before human testing begins.

Cell model: An artificial lab set up that uses cultured cells to study biological mechanisms or drug responses.

Animal model: Non-human animal species used to simulate human disease pathologies and assess therapies.

Trial phase and outcome terms

Phase 1 trial: The first stage of human clinical testing, when the safety, dosage, and side effects are assessed in a small group of people.

Phase 2 trial: A clinical trial stage evaluating efficacy, optimal dosing, and side effects in a larger patient group.

Phase 3 trial: Large-scale testing comparing a new treatment against standard therapies to confirm safety and effectiveness.

Endpoint: A targeted clinical outcome or metric measured during a study to assess an intervention's effect.

Primary endpoint: The main designated measure used to determine if a clinical trial successfully met its objective.

Secondary endpoint: Additional measured outcomes that provide supplementary safety, efficacy, or quality-of-life data.

Safety: The measure of whether a treatment's benefits outweigh its risks and adverse side effects.

Efficacy: The capacity of an intervention to produce a desired beneficial effect under controlled trial conditions.

Tolerability: The extent to which a patient can endure a treatment's adverse side effects without stopping therapy.

Adverse event: Any unwanted or harmful medical occurrence experienced by a participant during a clinical trial.

Serious adverse event: A severe adverse event associated with a medical treatment or clinical trial resulting in death, life-threatening illness, hospitalization, or persistent disability.

6. Research Terms

Mechanism: The specific biological pathway or step-by-step process through which an effect occurs.

Hypothesis: A testable proposition or proposed explanation made based on limited evidence.

Model system: A simplified biological setup (e.g., mice, cultured cells) used in research to simulate complex biology.

In vitro: Experiments conducted outside of a living organism, such as a petri dish or test tube.

In vivo: Experiments that occur within a living whole organism.

Correlation: a mutual relationship or connection between two variables, without proving one causes the other.

Causation: a direct cause-and-effect relationship between two variables, in which one event produces the other.

Association: a statistical connection between two traits or conditions without proving a direct cause.

Therapeutic target: a specific biological molecule, such as a protein or a gene, that a drug is designed to act upon to alter disease.

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NAD+: A critical coenzyme present in all cells that powers metabolism and cellular repair processes.

Coenzyme: A non-protein compound that binds to an enzyme to help it activate and carry out its specific chemical reaction in the body.

NMN: A precursor molecule that cells convert into NAD+ to maintain energy and repair functions.

SARM1: An enzyme that promotes axon degradation when neurons are damaged or stressed.

Hormone: A chemical messenger released into the bloodstream to regulate distant physiological functions.

Cortisol: A primary steroid hormone released in response to stress that regulates metabolism and immune function
 

7. Supplements and Evidence Terms

Antioxidant: a substance or molecule that neutralizes dangerous free radicals to prevent cellular oxidation damage.

Anti-inflammatory: A compound or agent that reduces tissue swelling, immune reactivity, and inflammation.

Bioavailability: the proportion of an ingested drug that successfully makes it to the bloodstream to take effect.

Dose: the measured quantity of medicine, drug, or supplement that is recommended to take at one time.

Deficiency: a state when essential vitamins or minerals fall below levels required for healthy function.

Drug-supplement interaction: an altered medical outcome caused when a dietary supplement interferes with the action or safety of a drug.

Contraindication: A specific condition, medical factor, or drug scenario that renders a particular treatment unsafe.

Quality control: Standardized manufacturing procedures designed to ensure products are consistently pure, safe, and accurate.

Purity testing: Analytical testing performed to confirm that a product contains its listed ingredients free of contaminants.

Third-party testing: Independent laboratory testing performed by an unbiased organization to verify product quality.

Contamination: The unintended presence of harmful or foreign substances (e.g., heavy metals, bacteria) in a product.

Proprietary blend: A custom mixture of ingredients listed as a single group on a label without disclosing exact dosages.

Marketing claim: Statements made by a manufacturer regarding the supposed health benefits or capabilities of a product.