Science questions for kids | Why do you need to go to the toilet even if you haven't eaten or drunk anything?

Rajatorpa school's elective students, Vantaa

Enjoyed the fluids are usually passed out through the urinary tract as urine within a few hours.

If you have had a lot of fluids recently and your bladder is already full, you may have to urinate a few minutes after drinking. If a person is dehydrated and the bladder is empty, it can take hours.

The passage of the eaten food as a whole through the digestive system and the speed at which the stool comes out depends a lot on the person and the food. On average, it takes one to three days.

The need to urinate usually strikes when the filling of the bladder irritates the stretch receptors in the bladder wall.

The receptors send messages via nerves to the spinal cord and from there to the brain, where the need to urinate is detected. The function of stretch receptors varies from person to person and even within the same person depending on the situation.

Especially if you are tense, anxious or nervous, the body may go into the so-called fight or flight mode. The adrenaline hormone is secreted, the pulse rises and the urge to urinate strikes.

Habits also have an effect. For example, if you always urinate when you leave the house, the emergency will often strike when you leave, regardless of the amount of food or liquid consumed.

In addition to the food consumed, the need to defecate is also affected by other factors such as the secretion of digestive fluids, other digestive functions, undigested food and mental activity. That's why the need to defecate can strike, even if you haven't eaten anything recently.

Kari Tikkinen

professor of urology and general practitioner

University of Helsinki, Eksote and HUS

Why does gold shine?

Jesse Rissanen, 6

All substances consist of tiny atoms. Most substances are combinations of different atoms, but gold is an element. This means that pure gold consists exclusively of gold atoms.

The gold atom reflects even the smallest ray of light, which is why gold shimmers or shines. This is thought to be due to the shape of the tiny gold atoms.

All atoms have a nucleus surrounded by shells of electron particles. All substances can be said to be covered with electrons. So is gold.

A gold atom has six electron layers, or veils. There is only one electron in the outermost shell.

When the light hits this lone electron, it starts to ripple, i.e. as if dancing together with the light rays hitting it. This tiny little movement makes the gold shine.

Gold belongs to the elements and precious metals. Although the outermost electron reacts to light rays, it does not react with air or water – in other words, gold does not rust and its surface remains clean. That's why gold keeps its shine perfectly.

Polishing the gold smoothes its surface, so that the rays reflected by the dancing electrons come more abundantly in the same direction, for example to the viewer's eye. Therefore, it seems to us that polished gold would shine more

Fairy tale Hietala

geologist

Arto Hyvönen

geologist

Geology Research Centerp

How do elephants burp?

Vilma Heikkilä, 3

Burping usually happens when air enters the stomach, e.g. when eating or drinking, and it leaves the mouth through the esophagus. In addition, fizzy drinks, such as soft drinks, contain carbon dioxide, which is also removed from our bodies as belches.

Air going in increases the pressure in the stomach, which opens the seal at the top of the stomach, allowing the air to escape. If a lot of air passes, it vibrates the structures of the neck and the mouth of the stomach, among other things, which causes a belching sound.

An elephant can also burp. Its belching happens in the same way as in humans and other animals. However, it is not a wild burp, although it can drink up to 200 liters of water per day.

An elephant has a similar digestion to a horse. It calmly eats plants and breaks them down mainly in the large intestine. In this case, the air and other gases that may come from eating and breaking down the food mostly come out through the anus. Elephant farts are often quite loud!

Ruminants in particular, such as cows, are harder burpers than elephants. With them, the food travels back and forth between the stomachs and the mouth, causing a lot of belching as the food breaks down.

Vesa Paajanen

university lecturer in animal physiology

University of Eastern Finland

Why are the fingers of a hand all different sizes?

Ida Santaharju, 9

Different sizes the fingers make the hand more versatile. We can hang, climb and lift even small objects. We can also make precise movements, such as drawing. The fingers are just the right length for all of this.

Of the fingers, the thumb is special. It is shorter than the other fingers, has only two joints, and moves in several directions. When we grip a pen, we place it between our thumb and another finger, usually the index finger.

Our close relative, the gibbon, has a very long thumb and would wrap its thumb around a pen without the help of other fingers. This allows the gibbon to carry a pen inside its thumb and use its other fingers to hang from tree branches.

For people, hanging is not as important. Instead, it is important for us to grasp objects. Fingers of different sizes make it easier to grasp objects of different sizes, for example throwing a ball.

Human fingers are more different in size than primates in general.

There is also a difference between genders. Men's index finger is often shorter than the ring finger, while women have the opposite. A similar difference has been observed between females and males of other animals.

Finger length differences are also due to the hormones that make us boys and girls.

Summer Viranta

associate professor of paleobiology

university of Helsinki

Send the question, the questioner's full name and age to [email protected]. The column is edited by Touko Kauppinen and Juha Merimaa.