How humans breathe without thinking about it

Human anatomy 101: the body's systems

Human life is made possible by the body's ten major systems, which maintain homeostasis by responding to incoming sensory and biochemical input. Each system must work independently and collaboratively for the body to maintain health and respond appropriately to its internal and external environments. The bones of the skeletal system, for example, give the body its shape and protect organs while also facilitating movement with the muscular system.

Ten things to know about your heart

Your heart does amazing things day in and day out. Its main job is crucial: It keeps oxygenated blood circulating throughout your body. Did you know that, other than your cornea, every cell in your body gets blood from your heart? You may not think...

How the body produces urine

Things seem so simple when nature calls. But, how does the body actually produce the urine we so regularly and thoughtlessly expel? This detailed, comprehensive animation walks viewers through every step with precise illustrations, from the kidney's filters (known as nephrons) to the direct nerve connecting the bladder to the brain. See how the body does it here.

The human brain only uses 5% more energy during active tasks versus resting

Despite only being 2% of the weight of a human body, the average adult brain consumes 20% of its energy, with the majority of it spent on maintaining homeostasis—the stable equilibrium conditions of temperature, acidity, blood sugar, and other properties in the body. For infants, the consumption is closer to 50%.

How does the body know where it is in space?

Close your eyes and touch your nose. How did you know where your nose was? How could you tell where your hand was? That's proprioception, the sense that keeps your brain apprised of the body's position and movement. This article explains how this sense works, what happens when people don't have it, and what we know about it.

Some claim breathwork can improve mental health, help process trauma, and more

Research shows people who practice breathing exercises see a decrease in depression and stress levels, and that such exercises are about as effective at treating PTSD as conventional approaches. Even something as simple as extending exhales can slow one's heart rate and activate the parasympathetic nervous system.

Learn how your body is, scientifically, like a firework with its own slow, controlled burn

This NPR video makes clear that there are surprising similarities between how our bodies and fireworks function. Fireworks and our bodies are both packed with carbon atoms, and have controlled releases of energy that create heat—keeping the human body warm or fueling fireworks' heat, respectively. What's more, the human body even emits a tiny bit of light somewhat similar to fireworks—though it's not visible to the human eye.

Learn how your body is, scientifically, like a firework with its own slow, controlled burn.

How does your body turn food into energy?

Cells get energy via a process known as cellular respiration, which involves turning glucose into ATP or adenosine triphosphate. Breaking the phosphate bonds of ATP results in usable energy being released into cells, which can then use that energy to power biological processes. This 10-minute video explains how glucose turns into ATP, giving the body the energy it needs to survive.

A quick video on how your immune system works

Explore how your immune system’s vast network of cells, tissues, and organs coordinate your body’s defenses against bacteria, viruses and toxins with this 5-minute TED talk video.

Nasal hairs, called vibrissae, help protect the body from particulate matter and other dirt

The nose structure plays a key role in filtering air before it enters our lungs and makes sure that the air temperature and humidity are also suitable for the body.

Oxygen and nutrients are circulated in tardigrade bodies through physical movement

Rather than having a circulatory system, oxygen is directly absorbed through their skin and spreads through a fluid called hemolymph as tardigrades crawl. When molting to grow, they shed their outer skin and stylets—sharp mouth parts used to pierce prey—which are regrown in their salivary glands.

Humans can't smell the inside of their nose due to olfactory fatigue

Once a person is accustomed to a specific odor, their neurons have trouble continuing to respond to that smell because of that familiarity. That's why humans may not notice when their house smells like trash until they leave the house and then return to it.

Brain conditions and surgery can cause some individuals to feel no fear

Fear is a survival mechanism that originates in the brain's amygdala, triggering the body's fight-or-flight response. However, in modern society, without the same natural dangers, fear can lead to anxiety and mental health issues when unnecessarily triggered. Understanding individuals without fear may help identify new methods to treat anxiety disorders.

Sleep apnea explained

While sleep apnea is directly tied to an increased risk of cardiovascular and metabolic health problems, many affected people are unaware of their problem. Sleep apnea occurs when upper airway muscles relax during sleep and pinch off the airway, which can cause breathing to pause for 10 seconds or more at a time. Sleep partners (rather than those inflicted) are often the first to notice breathing pauses or loud snoring in their bedmates.

How neurons give rise to thoughts

Neurons in the brain are singular nerve cells that flicker on and off or connect to each other based on incoming stimuli. The more neurons communicate by firing electrical impulses through tendrils known as synapses, the stronger their connection becomes. The electrical energy zipping along these interneural connections in an attempt to classify and respond to incoming stimuli may be what gives rise to thoughts.

How specialized oxygen mixtures like heliox enable deep diving without feeling drunk

Beyond a depth of about 30 meters (98 feet), if divers are breathing surface air, which is about 78% nitrogen, underwater pressure forces more nitrogen into the bloodstream and induces nitrogen narcosis, whose symptoms resemble alcohol intoxication. Through saturation diving, where nitrogen is replaced with helium—an inert gas—deep divers can maintain cognitive function while working for extended periods.

The iron lung—a simple mechanical ventilator—was first used to treat polio

These breathing devices, developed in the late 1920s at Harvard, were used to treat polio patients with breathing difficulties. Watch this video describing how these negative pressure devices work.

Rubisco, the crucial enzyme powering photosynthesis

Photosynthesis is the crucial process by which plants absorb sunlight, take up water, and breathe in carbon dioxide, prompting chemical reactions that result in the byproducts sugar and oxygen. A key enzyme, rubisco, is responsible for it all, but it is inefficient. This video explores the key protein and reveals fascinating facts about oxygen and photosynthesis.

Yawning helps regulate heat in and around the skull

All vertebrates, including solitary animals, exhibit yawning behavior, and, despite long-standing beliefs, studies show no correlation between yawning and oxygen levels. Contagious yawning may enhance group coordination and vigilance in animals and involves advanced social cognitive mechanisms.

Most people breathe fungal spores daily without getting sick

Most people breathe in hundreds of Aspergillus fumigatus spores daily without getting sick—it’s a common microscopic fungus in our environment. But people who are severely ill, including those who have undergone an organ transplant, are at risk of developing infections from these spores.

What is it like to be a bee?

Scientists have long known the intimate features of bee anatomy: six limbs, five eyes, lots of hair, a long, tasteless tube -like tongue, and wings that stroke close to 12,000 times a minute. But getting inside the mind or consciousness of a...

Brain death is a top source of organ donation

Brain death is a significant source of organ donations because patients declared brain dead and hooked up to intensive care unit machines will still have oxygen flowing to organs like the heart, lungs, and kidneys—preserving those organs.

We dream for around two hours each night, on average

Every night we lie down to rest, we spend about two hours traveling through seemingly real experiences as dreams bubble up from our subconscious during various phases of sleep. Despite the ubiquity of the experience, where dreams come from—and what their purpose is—remains largely unanswered.

Nearly every major automaker now offers a hands-free driving system

The capabilities of these systems range from automatic lane changes via eye-tracking to an assistant that reminds you to check your blind spot before changing lanes yourself. Most systems still require the driver to remain alert and be prepared to take over.

A tube-and-diaphragm system tells gas pumps when to stop providing fuel

As long as air passes freely through a small hole at the end of the nozzle, the diaphragm is inflated, and fuel flows normally. Once fluid reaches the hole, the change in pressure from the difference in air and fluid densities collapses the diaphragm, which cuts the flow of gas.

Researchers believe the brain consolidates memories, processes emotions, and plans for the future during dream states

After 25 people used virtual reality headsets to practice flying with virtual wings—flapping their arms—their visual cortex responded to the wings almost as if they were real arms, treating them as body parts.

Bone marrow (soft tissue found inside certain bones) generates roughly 500 billion new blood cells each day

When you complete a CAPTCHA on a website to prove you are human, you may be unknowingly training algorithms for self-driving cars, whose systems require training data to help identify crosswalks, bicycles, and other outdoor objects.

Crows are believed to have intelligence on par with a seven-year-old child and demonstrate complex behaviors, from problem-solving with tools to recognizing human faces.

Tattoos remain visible on your skin thanks to immune cells called macrophages

Alzheimer's can lead to brain shrinkage, with an average of around 2% of volume reduction per year

While the sun's gravity keeps the planets in orbit, their gravity also pulls on the sun, causing it and everything else in the solar system to orbit around a mutual balance point called the barycenter—the true center of the solar system.

Visualize how CRISPR-Cas9—a type of immune system used by single-celled organisms to attack invasive viruses—targets and makes precise changes to a gene's DNA.

Some researchers have labeled nomophobia, the fear of being without your phone, as 'the phobia of the 21st century.'

Human-to-human transmission of hantavirus remains extremely rare, so the 2026 hantavirus cruise ship outbreak doesn't mean we're facing a COVID-style pandemic risk.

Ebola infects and disables immune cells, triggering a cascade of events that leads to small blood clots throughout the body, weakening blood vessels and interrupting blood flow to key organs.

Explore the history, structure, and species of Australia's Great Barrier Reef with this interactive journey narrated by Sir David Attenborough.

Read a deep dive on the 'all-purpose healing' peptide BPC-157.

Double world record holder Hunter Ewen helped conquer his fear of balloons, called globophobia, by training to win Guinness World Record titles for balloon inflation.

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

Pure water does not conduct electricity because this flow of energy requires the movement of charged particles, and water is a neutral molecule.

Before humans, the Soviet Union and the United States sent animals—including apes, dogs, and cats—to space during the Space Race.

SpongeBob exemplifies Aristotle's philosophy for living well because he understands that happiness doesn't come from external factors like money, recognition, or power.

Discover the catastrophic consequences of a failure of the US electrical grid—something that is more likely than many Americans think.

How Amazon operates a 'flywheel' business model, a self-reinforcing cycle that drives continuous growth

The first robot in literature may have been a 'mechanical man' in 1907's 'Ozma of Oz,' a book in L Frank Baum's 'Wizard of Oz' series.

The Mona Lisa's celebrity status and repeated restorations have obscured what made the painting so revolutionary for its time

Use this calculator to find the dollar value of your mental load, from meal planning to coordinating after-school care for your children.