Animals, including humans, use their senses to communicate with and make sense of the world outside of their bodies. How important are these senses? Imagine living in a body that has all of the senses except hearing. The body could rely on the other four senses but would probably rely most on sight and touch. If another sense is lost, like sight, then relying on the other three senses would be challenging. The loss of touch would leave only smell and taste. Surviving with only these two senses would be very hard! The senses work together to help the body survive in the world.
There are five basic tastes for humans: salty, sweet, sour, bitter, and umami. Taste starts in the mouth with the tongue and also includes the nose. The tongue has taste receptors, or buds, located all over it. Salty, sweet, sour, and bitter tastes are fairly common. Foods can be one taste or a combination of tastes. A good example of a combination of sweet, sour, and bitter is cranberries. Umami, meaning "delicious" in Japanese, is a less-common thing to taste. This taste, unlike the other four, is a blending of tastes to create a one-of-a-kind flavor. It's a meaty, earthy sort of taste. Foods with umami include steaks, stinky old cheese, and mushrooms. Foods high in the amino acid glutamate have the umami flavor.
Smelling begins with the nose sniffing air, which moves into the nose through the nostrils. The air makes contact with olfactory receptors that analyze the air contents. The information is then sent to the brain through the olfactory nerve, and your brain uses this information to figure out what the smell is. The olfactory receptors in the nose are also used for taste. As you're eating a food, the smell goes through your nose and from your mouth up into your sinuses, where it touches the olfactory receptors. This message is then sent to the brain and combines with the messages from the taste buds to make food taste stronger. If a person had no sense of smell, then they wouldn't be able to taste things as well. You can see this for yourself when you try to eat things while you have a bad cold; if your nose is stuffy and you can't smell, food doesn't taste as good.
Eyeballs are like the cameras of the body. The eyes are the camera lens, where light enters. Inside the eyeball, or camera, the light is translated into an image. Rods are sensors that pick up all of the black and gray in what you're seeing, and cones are the sensors that let you see colors. All of this information is upside-down because of how the rays of light enter your eye, and it's sent to the brain through the optic nerve. Since humans have two eyes, the brain creates a 3D image using the pictures from both eyes that lets you see how close or far away things are.
The skin is the organ of touch. Skin is the largest organ in the body, and it can feel four basic sensations: cold, heat, contact, and pain. Nerve endings in the skin help pick up these sensations and send them to the brain. Hair located on the skin can amplify touch. The fingers have the greatest sensitivity to touch. The sense of touch can also be emotional or comforting as well as physical. A good example of this is petting a dog or hugging someone. Touches like these can make you happy.
Hearing begins with the ear. Sounds travel through vibrations in the air called sound waves. These waves enter the outer ear and vibrate your eardrum. The waves then travel to the inner ear and are turned into messages that travel to the brain. The brain then interprets this as a sound. Interestingly, sometimes, sounds can be so loud that you can feel these vibrations with your skin, too.