Meet the 12 cranial nerves

How the five senses share information with each other

The human body depends on information from the five sensory organs—the eyes, ears, nose, tongue, and skin—to react to the world around it. Each of these organs, in its own way, relies on complex circuitry to send signals back to the central nervous system.

Explore an interactive 3D model of the brain

The brain contains about 86 billion neurons—nervous system cells—and controls vital bodily functions via electrochemical signals. Neurons form circuits through axons, and different brain regions use these circuits to perform specific tasks.

The body's master clock has 20,000 neurons

The suprachiasmatic nucleus, the master clock in mammals, has 20,000 neurons that help maintain the light-dark cycle in the body. Among its jobs: It receives light input information from the retina and then signals peripheral body clocks to act on this information, driving everything from body temperature to hunger.

What is the peripheral nervous system?

This nervous system extends throughout the body, where it acts as the informational bridge between the central nervous system, housed in the brain and spinal cord, and the body's muscles and organs. The peripheral nervous system is further divided into the autonomic, enteric, and somatic nervous systems, each of which oversees certain muscle types and processes. This article overviews the anatomy and functions of the peripheral nervous system.

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.

Scientists have unraveled new details about which nerve cells control goose bumps

Research in 2016 revealed that at least eight different types of neurons are associated with the sympathetic nervous system. One finding revealed that goose bumps and nipple erection are caused by neurons specialized to regulate these specific functions by controlling the erectile muscles in those tissues.

Each taste bud has 10 to 50 sensory cells that form a flower-like capsule

At the top of the structure are thin filaments known as "taste hairs" that bind taste-producing substances to the surfaces of the cell, after which corresponding electrical signals are sent to the brain. Adults have 2,000 to 4,000 taste buds on their tongue.

Listen to how the gut microbiome influences your emotions

The gut-microbiome connection may involve the enteric nervous system, a collection of hundreds of millions of neurons throughout the gut that transmit signals up the vagus nerve to the brain.

Mind-controlled bionic arms use nerve implants to restore sensation and movement

Unlike traditional prosthetics that rely on surface electrodes or mechanical parts, this system uses implanted titanium and nerve-connected electrodes to enable a seamless brain-to-arm connection. Patients train in virtual reality with their implanted signals before using the physical prosthesis.

Brain hemispheres control opposite sides of the body without either dominating

Although distinctions exist between the two halves—language processing is left-oriented, and emotions are right-oriented—signals are sent along neural pathways between the hemispheres and across different regions to collectively process information about external stimuli.

How muscles get their names

There are more than 600 muscles that crisscross the human body, and each has a name that's more than a simple label. Muscle names also typically communicate the muscle's size, behavior, length, location, appearance, direction, and attachments to bone. These names usually have Greek or Latin roots, such as in the case of the deltoid muscles, which are named in reference to the Greek letter delta (𐤃).

Watch how your nervous system's efforts to process silence can contribute to tinnitus

Cochlear cells can be damaged in numerous ways, including aging or exposure to loud noise. If enough cells die, the auditory system can become less sensitive, prompting the brain to compensate by amplifying sound, which is likely to contribute to tinnitus.

Sensory memory is information collected from your senses

Lasting seconds before moving into short-term memory or being forgotten, sensory memory aids in environmental awareness and navigation. Key brain regions involved include auditory, somatosensory, gustatory, visual, and olfactory cortices.

A dog's central sniffing organ is many times bigger than a human's

The olfactory epithelium, located high up within the human nose, is home to millions of olfactory neurons. A dog's olfactory epithelium is much larger—and has more neurons—than a human's, which helps to explain the animal's superior sniffing ability.

Exercise releases chemicals that enhance cognitive function

Neurotransmitters like dopamine, serotonin, and norepinephrine, along with increased brain-derived neurotrophic factor levels, enhance a wide range of brain functions. New research demonstrates a direct link between movement and numerous cognitive benefits, including memory, learning, and stress resilience.

Some animals may speak because of duplicated connections in the brain

Neuroscience suggests that connections responsible for motion made during embryonic brain development—such as those connecting hearing and movement pathways that allow reactive motion when started—are duplicated and connected to the larynx in some animals. This allows some mammals and song-learning birds to speak, provided they have the necessary physiological structures.

Anosmia is the total loss of the sense of smell

This type of loss—due to disease or trauma—has ripple effects, including an altered or limited sense of taste. This video details the anatomy and physiology of our sense of smell and taste and how these senses are interrelated.

Do trees feel pain?

Trees don’t have nerves or brains. But when they’re wounded, they send underground and airborne warnings to other trees.

Vertigo is a mismatch of information between the eyes and the ears

Both vertigo and motion sickness can be caused by mismatches between visual and auditory inputs.The brain relies on inputs from the eyes, inner ear, and receptors in muscles and joints to orient the body. When the eyes suggest movement but other signals suggest the body is stationary dizziness and nausea can occur.

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.

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.

Half of human DNA is inherited from each parent

Within most cells reside 23 pairs of chromosomes made of tightly wound DNA, and half of each pair is inherited from each parent. The 23rd pair consists of two X-shaped chromosomes, or one such chromosome paired with a Y chromosome, and determines biological sex.

What is the immune system? A quick 101

Your body’s immune system is designed to protect you from infection. Find out more about how the immune system works with this quick overview and set of diagrams.

What are neural networks and why do they matter?

Learn how a neural network works, why it matters, and how it can be trained to recognize patterns, classify data, and forecast future events.

Test your emotional intelligence with this quiz

Emotional intelligence is the instinct and art of understanding feelings: both your own and those of others. Studies demonstrate people with high emotional intelligence often succeed in leadership positions, as they can better serve the real needs...

Can you guess which ancient human skull is which?

When scientists discover a new fossil skull, they compare it to skulls that have already been identified as particular early human species. In this activity, you get the chance to be the scientist! Choose a mystery skull to identify by clicking on it.

Recent research found that the brain doesn't seem to massively rewire following amputation—upending earlier beliefs about the cause of phantom limb pain.

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

See how each of the more than two million known species relates to each other—and to common ancestors—in this zoomable tree of life.

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.

Power lines are dotted with large, brightly colored balls to improve the visibility of these thin wires to helicopters and small planes and help prevent potential crashes.

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

Lesser-known phobias include turophobia, or the fear of cheese, and nomophobia, the fear of being without your cell phone.

Studies suggest when you sleep is as important as how much you get, and syncing with your circadian rhythms may lead to less fatigue and improved long-term health outcomes

The Nasdaq's 'Magnificent 7' companies are responsible for roughly 40% of the Nasdaq 100 index's gains, while the remaining 93 companies account for the other 60%.

This poison ivy knowledge quiz—accompanied by photos of the plant's varied forms—may help you identify this common rash-inducing growth.

Track the location of the Voyager probes, currently between 13 and 15 billion miles away from Earth.

A pickleball's loud 'pop' sound can reach 120 decibels, which is equivalent to a hammer hitting a nail

This site reaches millions of visitors who are tired of AI chatbots and seeking human connection. Pretend to be an AI chatbot and ask questions, provide answers, and draw for people in real time.

The syncytiotrophoblast is the outer layer of the placenta and the largest human cell, spanning an area about twice that of a king-sized bedsheet.

The United States is one of only around two dozen countries with a fully federal system of government, in which power is divided between national and state governments.

See the 25 of the best photos of auroras from around the world.

According to the physics of black holes, our 4D reality may be a hologram—a projection of information coded on a 2D surface on the edge of the universe.

The Dracula character, now seen as the vampire archetype, was inspired by a seafood-induced nightmare its creator experienced.

The hormonal disorder PCOS was renamed PMOS in 2026, a move designed to improve care and research by shifting the focus to the hormonal causes of this condition that affects 1 in 8 women.

The first steps to rebuilding your credit score include getting to know exactly what's on your credit report and figuring out how far you are from the '700 club,' or 'good score' range.

For centuries, Niagara Falls has been a magnet for daredevils seeking to conquer one of nature's most powerful wonders, with its 200-foot drop and water rushing at 32 feet per second with 280 tons of force.

Hurricanes, which rely on air consistently spinning in the same direction, cannot cross the equator because air curves in opposite directions north and south of it.

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

See 33 images that became central to huge scandals, including a young Charles and Camilla, Michael Jackson's baby on a hotel balcony, and Hugh Grant's mugshot.