Infrasound Sound is a vibration that travels as a wave; infrasound is the extra-low part of the spectrum that we can’t hear. Infrasound is below 20 Hz, so we do not hear it, but we can sometimes feel it as a rumble. Why it travels far: Low frequencies have long...

Mirrors: Light That Bounces Mirrors create images by reflecting light in predictable ways. Flat (plane) mirrors: These make virtual images (which appear behind the mirror) the same size as the object, but with the left and right sides swapped. Concave mirrors (curved...

Current and Voltage Current is the flow of electricity, and voltage is the force that pushes it. Electric current is the flow of electrons through a conductor, measured in amperes (A). Voltage is the “electric pressure” or push that makes current move, measured in...

What is a Heart Attack? A heart attack happens when blood can’t reach part of the heart muscle. The medical term for a heart attack is myocardial infarction (MI) The heart is a muscle that needs a constant supply of oxygen-rich blood. Coronary arteries are the “pipes”...

How the Body Normally Handles Sugar The body maintains blood sugar balance using insulin, a hormone that controls how glucose enters cells for energy. When we eat food, especially carbohydrates, it breaks down into glucose (sugar). Glucose is absorbed into the...

Sensors in Your Skin Your skin is packed with special nerve endings that sense temperature and send signals to your brain. Your skin has thermoreceptors, tiny sensory cells that detect heat and cold. Warm Receptors - Above 86°F High-threshold Warm Receptors - Above...

Why Plants Turn Carnivorous Carnivorous plants evolved to hunt because the soils they live in cannot give them enough nutrients to survive. Carnivorous plants often grow in acidic, waterlogged soils like bogs and swamps. These soils are low in nitrogen, phosphorus,...

What Are Stem Cells? Stem cells are unspecialized cells with the powerful ability to develop into many different kinds of body cells. Pluripotent stem cells (like embryonic stem cells) can become any cell in the body. Multipotent stem cells (like adult stem cells) can...

What Are Good Bacteria? Good bacteria, also known as probiotics, play a critical role in maintaining a healthy internal environment. Your digestive system houses a vast microbiome—a community of microorganisms, mostly bacteria. Good bacteria help balance this...