World Book Trivia Challenge Advanced-6/18-senses

Taste is a component of flavor. But flavor also includes smell, touch, and temperature sensations.

Chemicals associated with the taste qualities of sour, salty, bitter, and sweet stimulate receptor cells of the taste buds. Some scientists think a fifth distinct taste, called umami, can be detected. This taste is usually described as “savory” or “meaty.” Japanese scientists were the first to describe it, The sensation of umami is caused by a chemical called glutamate. Glutamate is found in many protein-rich foods. However, not all scientists agree that umami constitutes a fifth category of taste.

Some animals respond to environmental stimuli that cannot be detected by human senses. These stimuli include ultraviolet light, Earth's magnetic field, sounds of very high and very low frequencies, and extremely small electric currents in water.

Touching an object can give rise to feelings of warmth, cold, pain, and pressure. Free nerve endings in the tissue give the sense of pain. Touch, warmth, cold, and pain also are called cutaneous senses.

A person can barely hear a sound of zero decibels. Sounds above 140 decibels can be painful to the ears. In some cases, they may seriously damage the ears.

The first eye bank was formed in 1944 in New York City. Many eye banks have since developed in other cities and countries. People who wish to donate their eyes should register with an eye bank.

Scientists do not know exactly how different smells are distinguished. One explanation is that molecules of certain odors become more quickly and more strongly attached to the mucus at a particular place on the turbinates than do other molecules. Therefore, molecules of certain kinds of odors will always stimulate the same receptor cells on the conchae. According to this theory, an odor is distinguished by how fast and where its molecules become attached to the receptor cells

Most animals have organs of some kind that sense light. The most elementary of these organs are called eyespots. Eyespots are light-sensitive areas on the bodies of flatworms, starfish, and certain other invertebrates (animals without a backbone). The organs can distinguish between light and dark but cannot form images

Touch is more sensitive in some parts of the body than in others. This difference is due to the fact that the end organs for touch are not scattered evenly over the body, but are arranged in clusters. The feeling of pressure is keenest where there are the greatest number of end organs. It is most highly developed on the tip of the tongue, and is poorest on the back of the shoulders. The tips of the fingers and the end of the nose are other sensitive areas.

Night blindness may be caused by various eye diseases or by a lack of vitamin A in the diet.