Category Zoology

The role of the eyes is to collect vast amounts of visual information, which the brain turns into 3D pictures of the world around us.

Each eye has a built-in lens to give a picture of the world and a bank of sensors to record it. Human eyes can focus on anything from a close-up speck of dust to a galaxy across the universe, and work in both faint moonlight and dazzling sunshine. The lens in each eye focuses light rays together on the back of the eyeball. Receptors record the patterns of light, shade, and colours, then send them to the brain to make an image.

Three pairs of muscles control the movements of each eye, allowing it to swivel and roll to look up, down, or from side to side. The muscles are fast-acting, so the eye can easily follow a moving object.

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This scan of the surface of the tongue shows that it is not smooth but is covered by a variety of tiny bumps called papillae.

The large, mushroom-shaped papillae house taste buds that detect five different tastes in food as a person eats. The spiky papillae lack taste buds but help the tongue grip food and move it around the mouth during chewing. Also visible is a scattering of small, dead cells that are constantly worn away from the tongue’s surface and then replaced.

The anterior two-thirds of the tongue contains the fungiform papillae. Each fungiform papilla contains up to eight taste buds, as well as somatosensory receptors for the sensations of pressure, touch, and temperature. The back edge of the tongue is marked by up to eight parallel folds called foliate papillae. The foliate papillae contain a total of approximately 1,300 taste buds. The final group of papillae is located in an inverted-V shape across the posterior third of the tongue. These circumvallate papillae are distinguished by their broad flat surface at the tongue’s surface, surrounded by deep and wide recesses. They contain a total of approximately 250 taste buds.

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The tongue has thousands of taste buds, but these receptors can recognize only five different basic tastes.

Bitter

Tasting something bitter can stop us eating harmful food. But some people enjoy bitter tastes, like coffee. Furthermore, there are cases where some bitterness could be healthy. Antioxidants, which aid in metabolism, account for the bitter taste in dark chocolate and coffee.

Dark chocolate shavings on top of your favorite holiday dessert could be a great addition to create a fun bitter flavor party.

Salty

This taste comes from sodium, which helps regulate muscle contractions, nerve signals, and keeping the right balance of water. As a flavor enhancer, adding salt to traditionally sweet dishes is necessary to amplify the sweet notes. A pinch of salt is core to most baked dessert recipes. Even if it is not listed in the ingredients, sprinkling some sea salt flakes or smoked salt over holiday ginger bread cookies brings out the sweetness of the sugar and enhances the ginger flavor.

Sour

Acidic foods, such as lemons and vinegar, taste sour. Humans are the only animals to enjoy sour food. The sour taste can also be obtained from foods soured through fermentation such as sauerkraut and yogurt, or through the addition of vinegar.

Many salad dressings feature vinegar as a key ingredient, which is a perfect way to add sour notes. You could also try adding lemon or orange zest to vinegar or even cream based dressings. Or, simply zest the top of your salad to help drive this craveable flavor sensation.

Sweet

Sweetness is naturally attractive as it indicates that presence of sugar, which provides a swift energy boost. Furthermore, when used in a combination, sweet complements well with the other basic tastes. Adding sweetness such as a drizzle of sweet balsamic glaze to a traditionally salty vegetable dish like roasted brussel sprouts would take it to the next level.

Umami

This is a mouth-watering savoury taste, found in foods such as grilled meat, mushrooms, or soy sauce.  In the early part of the 20th century, a Japanese chemist named Kikunae Ikeda attempted to identify this taste common to asparagus, tomatoes, cheese and meat. But, not one of the four well-known tastes could describe it adequately. What he pinpointed was the presence of glutamic acid, which he renamed “umami”, Japanese for “good flavor”. Though one of the core flavors of Eastern cuisine imparted by soy sauce and MSG (monosodium glutamate), it wasn’t accepted as a basic taste in the West until 1985.

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We use our senses of smell and taste to ensure we don’t eat harmful things. Our sense of smell can also detect other potentially dangerous substances, such as smoke or toxic chemicals. The brain processes these smells and warns the body to steer clear.

Doctors used to be able to sense when a person had a serious disease. Some people say they can sense when others are going to die.

Although researchers had studied effects on plants and animals, not much has been done in this area on humans. One reason is that it is more difficult to be subjective with human tests.

This small study may provide further scientific insights around conscious and non-conscious responses to threats. But the claimed connection between this research and humans having some type of ‘sixth sense for danger’ is as slender as a spider’s thread. 

This was a highly experimental scenario and it is not clear if these findings would be representative of the general population in real-life fear situations.

Warning signal!

When fresh foods such as milk go off, the sour smell quickly lets us know. Wrinkling the nose in disgust partly blocks off unpleasant, potentially harmful odours.

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The tongue and nose act as gatekeepers to the body, sending signals to help the brain decide whether or not substances are safe to allow into the body. Millions of sensory receptors lining these areas can detect more than one trillion different smells and tastes.

Molecules in the air we breathe attach to receptors lining the sensory cells of the nasal passages, while molecules in the food we eat attach to taste receptors on the tongue. When “good” molecules are detected, the brain sends messages to the digestive system to prepare for an intake of food. More saliva is produced in the mouth, and the stomach may rumble in anticipation.

Combined senses

Smell and taste act as combined senses in the brain to create the perception of flavor. But the sense of smell is 10,000 times more sensitive than taste. To understand how much enjoyment of food comes from the smell, pinch your nose closed and eat your favourite food.

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Different shaped teeth perform specific tasks. Sharp-edged incisors at the front cut into foods, while pointed canines are good for tearing. The cut food is then pushed back to the molars and premolars for grinding and chewing.

Milk teeth

A set of milk teeth consists of 20 teeth – 10 each in the upper and lower jaw. There are four molars for chewing food, but no premolars.

Ways to prevent milk tooth decay are similar to those for preventing adult tooth decay and include maintaining good oral hygiene and not allowing an infant or child to fall asleep with a bottle containing formula, fruit juices or sweetened liquids.

Healthy milk teeth help a child to eat, chew and speak normally and decayed teeth can hamper the child’s ability to eat normally, therefore affecting growth and development. In addition, a decayed primary tooth can lead to infection that may damage the permanent tooth growing underneath.

Permanent teeth

By the age of about 11, a child has a set of 28 permanent teeth. In the late teens, four more molars – the wisdom teeth – may appear, making a set of 32.

Permanent teeth can last a lifetime and it is very important to maintain them to prevent tooth decay developing and damaging them. Tooth decay can be prevented through brushing and flossing daily and attending regular dental checkups. These maintenance techniques prevent plaque from forming across the teeth and eroding the enamel and causing decay of the material inside.

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