activate: (in biology) To turn on, as with a gene or chemical reaction.
asthma: A disease affecting the body’s airways, which are the tubes through which animals breathe. Asthma obstructs these airways through swelling, the production of too much mucus or a tightening of the tubes. As a result, the body can expand to breathe in air, but loses the ability to exhale appropriately. The most common cause of asthma is an allergy. Asthma is a leading cause of hospitalization and the top chronic disease responsible for kids missing school.
bacteria: (singular: bacterium) Single-celled organisms. These dwell nearly everywhere on Earth, from the bottom of the sea to inside other living organisms (such as plants and animals). Bacteria are one of the three domains of life on Earth.
cancer: Any of more than 100 different diseases, each characterized by the rapid, uncontrolled growth of abnormal cells. The development and growth of cancers, also known as malignancies, can lead to tumors, pain and death.
cell: (in biology) The smallest structural and functional unit of an organism. Typically too small to see with the unaided eye, it consists of a watery fluid surrounded by a membrane or wall. Depending on their size, animals are made of anywhere from thousands to trillions of cells. Most organisms, such as yeasts, molds, bacteria and some algae, are composed of only one cell.
chemical: A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H2O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.
COVID-19: A name given to the disease that erupted into a massive global pandemic in 2020. It first emerged in 2019 and is caused by a new coronavirus known as SARS-CoV-2. Symptoms can include pneumonia, trouble breathing, feeling too tired to walk more than a few steps, fever, headaches, low blood-oxygen levels, blood clots and brain “fog.”
diabetes: A disease where the body either makes too little of the hormone insulin (known as type 1 disease) or ignores the presence of too much insulin when it is present (known as type 2 diabetes).
diet: (n.) The foods and liquids ingested by an animal to provide the nutrition it needs to grow and maintain health. Sometimes this is a specific food-intake plan. (v.) To adopt a specific food-intake plan. People may adopt one for religious or ethical reasons, to address food allergies or to control a disease such as high blood pressure or diabetes. They may also adopt one in an effort to lose weight, although this can be unhealthy if not done under the guidance of a health professional, such as a physician or registered dietician.
field: An area of study, as in: Her field of research is biology.
germ: Any one-celled microorganism, such as a bacterium or fungal species, or a virus particle. Some germs cause disease. Others can promote the health of more complex organisms, including birds and mammals. The health effects of most germs, however, remain unknown.
gut: An informal term for the gastrointestinal tract, especially the intestines.
hormone: (in zoology and medicine) A chemical produced in a gland and then carried in the bloodstream to another part of the body. Hormones control many important body activities, such as growth. Hormones act by triggering or regulating chemical reactions in the body. (in botany) A chemical that serves as a signaling compound that tells cells of a plant when and how to develop, or when to grow old and die.
immune system: The collection of cells and their responses that help the body fight off infections and deal with foreign substances that may provoke allergies.
infection: (adj. infectious) A disease that can spread from one organism to another. It’s usually caused by some type of microbe.
inflammation: (v. inflame) The body’s response to cellular injury and obesity; it often involves swelling, redness, heat and pain. It also is an underlying feature responsible for the development and aggravation of many diseases, especially heart disease and diabetes.
iron: A metallic element that is common within minerals in Earth’s crust and in its hot core. This metal also is found in cosmic dust and in many meteorites.
link: A connection between two people or things.
mechanism: The steps or process by which something happens or “works.” It may be the spring that pops something from one hole into another. It could be the squeezing of the heart muscle that pumps blood throughout the body. It could be the friction (with the road and air) that slows down the speed of a coasting car. Researchers often look for the mechanism behind actions and reactions to understand how something functions.
mental health: A term for someone’s emotional, psychological and social well-being. It refers to how people behave on their own and how they interact with others. It includes how people make choices, handle stress and manage fear or anxiety. Poor mental health can be triggered by disease or might reflect a short-term response to life’s challenges. It can occur in people of any age, from babies to the elderly.
microbe: Short for microorganism. A living thing that is too small to see with the unaided eye, including bacteria, some fungi and many other organisms such as amoebas. Most consist of a single cell.
microbiome: The scientific term for the entirety of the microorganisms — bacteria, viruses, fungi and more — that take up permanent residence within the body of a human or other animal.
microbiota: The microorganisms that live in a particular place or geological period. Scientists call the entirety of the microorganisms in a human or other animal its microbiome.
nutrient: A vitamin, mineral, fat, carbohydrate or protein that a plant, animal or other organism requires as part of its food in order to survive.
nutrition: (adj. nutritious) The healthful components (nutrients) in the diet — such as proteins, fats, vitamins and minerals — that the body uses to grow and to fuel its processes. A scientist who works in this field is known as a nutritionist.
red blood cell: Colored red by hemoglobin, these cells move oxygen from the lungs to all tissues of the body. Red blood cells are too small to be seen by the unaided eye.
social: (adj.) Relating to gatherings of people; a term for animals (or people) that prefer to exist in groups. (noun) A gathering of people, for instance those who belong to a club or other organization, for the purpose of enjoying each other’s company.
stress: (in biology) A factor — such as unusual temperatures, movements, moisture or pollution — that affects the health of a species or ecosystem. (in psychology) A mental, physical, emotional or behavioral reaction to an event or circumstance (stressor) that disturbs a person or animal’s usual state of being or places increased demands on a person or animal; psychological stress can be either positive or negative. (in physics) Pressure or tension exerted on a material object.
symptom: A physical or mental indicator generally regarded to be characteristic of a disease. Sometimes a single symptom — especially a general one, such as fever or pain — can be a sign of any of many different types of injury or disease.
system: A network of parts that together work to achieve some function. For instance, the blood, vessels and heart are primary components of the human body’s circulatory system. Similarly, trains, platforms, tracks, roadway signals and overpasses are among the potential components of a nation’s railway system. System can even be applied to the processes or ideas that are part of some method or ordered set of procedures for getting a task done.
type 2 diabetes: (see also diabetes) A disease caused by the body’s inability to effectively use insulin, a hormone that helps the body process and use sugars. Unless diabetes is controlled, a person faces the risk of heart disease, coma or death.
virus: Tiny infectious particles consisting of genetic material (RNA or DNA) surrounded by protein. Viruses can reproduce only by injecting their genetic material into the cells of living creatures. Although scientists frequently refer to viruses as live or dead, in fact many scientists argue that no virus is truly alive. It doesn’t eat like animals do, or make its own food the way plants do. It must hijack the cellular machinery of a living cell in order to survive.
vitamin: Any of a group of chemicals that are essential for normal growth and nutrition and are required in small quantities in the diet because either they cannot be made by the body or the body cannot easily make them in sufficient amounts to support health.
white blood cells: Blood cells that help the body fight off infection.