Have you wondered what controls the most basic functions of our bodies, like breathing, moving, and sleeping? Chemicals called neurotransmitters play a central role. Neurotransmitters pass messages from one nerve cell to another, and sometimes to muscles or glands. These messages may:
Prompt the next nerve cell to pass on the message, prevent the message from going any further, or adjust how the message is passed on
Cause a muscle to contract, like our intestines do when they digest food
Hormones are chemical messengers in the body that glands form and release, or secrete, into the bloodstream, where they travel to various organs and tissues to change biological functions. Hormone levels fluctuate during a lifespan and even on a daily basis.
Growth spurts in toddlers or sudden changes in adolescents are directly related to large hormonal shifts during development and puberty. Smaller changes occur throughout each day to help maintain normal bodily functions, such as our sleep-wake cycle known as our circadian rhythm.
This post is part of a miniseries on genetics. Be sure to check out the other posts in this series that you may have missed.
DNA carries information needed for all cellular functions. Credit: NIGMS.
You may wonder how scientists study something as tiny as DNA. Over the past decades, researchers have developed a wide range of tools and techniques to help them unlock the secrets of human genomes and those of other organisms. Two key examples are DNA sequencing and gene editing.
DNA Sequencing
DNA sequencing, sometimes called gene or genome sequencing, enables researchers to “read” the order of the bases in a segment of DNA, which contains the information a cell needs to make important molecules like proteins, the functional building blocks of the cell. There are several methods for sequencing, but they all require many copies of the same DNA segment to get accurate results. Fortunately, scientists have developed a technique called polymerase chain reaction, often referred to as PCR, that can quickly and inexpensively create a large number of copies of a DNA segment.
Beta-galactosidase, also known as lactase, a metabolic enzyme that breaks down the sugar lactose. Credit: PDB 6DRV.
You’ve likely heard someone attribute their body size to a fast or slow metabolism. But did you know there’s much more to metabolism than calories burned? Metabolism includes all the chemical changes that occur as our bodies use enzymes to break down food, medicines, and biological substances as well as produce energy and materials needed for growth.
The Two Sides of Metabolism
Our bodies have many metabolic pathways, but they all fall into two main categories: catabolic and anabolic. Catabolic pathways break down complex molecules into simpler ones, usually releasing energy in the process. For example, catabolic pathways turn large carbohydrate molecules from our food into simple sugars, such as glucose. Some of the most well-known catabolic pathways then convert the simple sugar glucose into adenosine triphosphate (ATP), a molecule that cells commonly use as an energy source.
This post is part of a miniseries on genetics. Be sure to check out the other posts in this series that you may have missed.
Have you ever been told that you have your mother’s eyes? Or maybe you’ve found that you and your father share a condition such as asthma? People who are biologically related often have similarities in appearance and health because they have some of the same geneticvariants. However, you’ve likely noticed that siblings with the same biological parents can differ significantly. Each person’s genome is a combination of DNA from both of their parents, but siblings’ DNA can differ because of the mixing and matching involved in creating reproductive cells.
Genetics is the study of genes and heredity—how traits are passed from parents to children through DNA. A gene is a segment of DNA that contains instructions for building one or more molecules that help the body work. Researchers estimate that humans have about 20,000 genes, which account for about 1 percent of our DNA. The remainder of the DNA plays a role in regulating genes, and scientists are researching other potential functions.
Have you ever noticed a skin care product advertised as “microbiome friendly” and wondered what that meant? The microbiome is the collection of all the microbes—including bacteria, viruses, and fungi—that live in a specific environment, such as on the skin or in the digestive tract.
Escherichia coli (E. coli) is a bacterial species commonly found in the human intestine. While some strains of E. coli cause foodborne illness, others are helpful members of the gut microbiome. Credit: Mark Ellisman and Thomas Deerinck, National Center for Microscopy and Imaging Research, University of California, San Diego.
It’s a common misconception that all microbes are harmful—in truth, much of the human microbiome is made up of microbes that form beneficial symbiotic relationships with us. Microbiome-friendly skin care products don’t have antimicrobial properties that could harm the beneficial bacteria that live on our skin.
This post is part of a miniseries on the immune system. Be sure to check out the other posts in this series that you may have missed.
Credit: NIGMS.
Throughout our immunologyminiseries, we introduced the immune system and its many functions and components. Additionally, we highlighted how vaccines train your immune system, how the system can go awry, and how NIGMS-supported researchers are studying immunology and infectious diseases. Put your knowledge about the immune system to the test by taking the quiz below.
It’s common knowledge that too much cholesterol and other fats can lead to disease and that a healthy diet involves watching how much fatty food we eat. However, our bodies need a certain amount of fat to function—and we can’t make it from scratch.
Hepatocytes, like the one shown here, are the most abundant type of cell in the human liver. One important role they play is producing bile, a liquid that aids in digesting fats. Credit: Donna Beer Stolz, University of Pittsburgh.
Triglycerides, cholesterol, and other essential fatty acids—the fats our bodies can’t make on their own—store energy, insulate us, and protect our vital organs. They act as messengers, helping proteins do their jobs. They also start chemical reactions that help control growth, immune function, reproduction, and other aspects of basic metabolism. Fats also help the body stockpile certain nutrients. Vitamins A, D, E, and K, for example, are stored in the liver and in fatty tissues.
The cycle of making, breaking, storing, and using fats is at the core of how all animals, including humans, regulate their energy. An imbalance in any step can result in disease. For instance, having too many triglycerides in our bloodstream raises our risk of clogged arteries, which can lead to heart attack and stroke.
This post is part of a miniseries on the immune system. Be sure to check out the other posts in this series that you may have missed.
The immune system is designed to closely monitor the body for signs of intruders that may cause infection. But what happens if it malfunctions? Overactive and underactive immune systems can both have negative effects on your health.
