The toothbrush is a tool to clean teeth. The toothbrush has a small brush at the end of a handle. Toothpaste, which often contains fluoride, is commonly added to a toothbrush to help clean the teeth. Both toothpaste and toothbrushes come in many different colours. Toothpastes can also come in many different flavours. Nice toothbrushes (especially electrical) can make toothbrushing fun and help your child on the way to perfect oral health.
Toothbrushes were first invented by a prisoner. Before anyone had thought of a toothbrush, people kept their teeth clean by chewing on a stick until one end got soft and frayed like a brush. Sometimes they dipped a finger in chalk or salt and then rubbed their teeth. Toothpicks were another way to take care of teeth, and toothpicks were very fancy then. They were made of gold or jewels, and people would stick them in their hats or hang them on necklaces when they were not using them.
The first brushes came from China, where the Chinese made them out of hairs pulled from the back of wild hogs. The kind of toothbrush we know came from William Addis. He worked on the toothbrush while he was in jail. First, he saved a bone from one of his meals and poked some holes in it. The prison guard gave him some bristles. Joseph tied the bristles into little bundles, cut them to make them even, put glue on the ends, and stuffed them into the holes. The company he started still make millions of toothbrushes every year.
The word toothbrush came from the two parts of the word, first a noun and then a verb or noun. The action of brushing teeth with a toothbrush is basically the use of the invention of Joseph Addis.
70s BC
20s BC
Homeostasis
Homeostasis is self-regulation, a basic property of all self-organising systems. In biology, it is the keeping of a stable internal environment.
Homeostasis is life's ability to stay balanced, when the environment changes. Animals keep their body in a stable condition. They do so by regulating their inner equilibrium . For example, they adjust their pH, temperature, amount of oxygen or carbon dioxide in the blood and so on. In living things, the study of how they keep in a stable condition is called physiology. Mostly, our physiology works unconsciously throughout life. We have many negative feedback systems which adjust our physiology so that we stay alive. These systems are self-organising and do not need to be learnt. They are inherited.
The concept was described by Claude Bernard, and the term was later coined by Walter Cannon in 1926, 1929, and 1932. Walter Cannon thought these were the features of homeostasis:
Examples of homeostasis:
In mammals, the main organs involved with homeostasis are:
The brain is also central to homeostasis. It controls behaviour, and the basic function of behaviour is to support life by taking action.
Pulmonary embolism
A pulmonary embolism is a clot of material (an embolus) that blocks blood from getting to the lungs. It is usually caused by a blood clot that starts somewhere else in the body and travels to the lungs. However, it can also be caused by clumped cancer cells, fat, or bone. Rarely, while giving birth, a woman can get a clot of amniotic fluid.
Symptoms of a pulmonary embolism start suddenly, as soon as the clot starts blocking blood flow to the lungs. Blood is supposed to pick up oxygen in the lungs and then carry that oxygen to the rest of the body. If blood cannot get through to the lungs, it cannot pick up oxygen or deliver it to the body. Every part of the body needs blood and oxygen to survive.
Often, the first sign of a pulmonary embolism is syncope (fainting), because the brain is not getting enough blood and oxygen. Other symptoms include:
The worst kind of pulmonary embolism is caused by a "saddle embolus". This kind of embolus blocks the pulmonary artery, which carries blood from the right side of the heart to the lungs. This makes it impossible for any blood to get through to the lungs. Since no blood can get out to the rest of the body, the person's blood pressure drops and they can go into shock. A saddle embolus is a very serious medical emergency. Many people with this type of embolus die.
There are many risk factors that make it more likely for a person to get a pulmonary embolism. For example:
There are a few treatments for pulmonary embolism. The choice of which treatments to use depends on how serious the pulmonary embolism is. Treatments include:
Toilet
A toilet is a place where humans get rid of waste that comes from their bodies (urine and feces). Most toilets use water and to flush the waste through plumbing into a sewage system. However, some modern toilets do not use water, and are called dry toilets.
A room that has a toilet can be called a "restroom" or "bathroom" in the United States. In other places it may be called the toilet or the water closet (WC).
Almost all modern buildings have at least one toilet. In the home, a toilet may or may not be in the same room as a shower or a bathtub. Some toilets are outside, in an "outhouse".
In developing countries, many people do not have a toilet in their home. More than 4.5 billion people do not have access to toilets.
A public toilet may or may not cost money to use. Toilets that cost money are called "pay toilets".
Public bathrooms often have many toilets with walls between them. This makes areas called "stalls" (US) or "cubicles" (UK). Bathrooms for men often also have separate urinals. Urinals can either be on the wall for a single user, or a basin or trough for many men to use at the same time. Urinals on walls sometimes have small walls or dividers for privacy reasons.
Outdoor public toilets (in the street, around parks, etc.) are a form of street furniture. These toilets are in individual cubicles. Some are simple and have little or no plumbing. Others are less simple, and some toilets even clean themselves after every use.
Some toilet-cubicles are mobile and can be put in place where and when they are needed. These toilets are called "portable toilets". Portable toilets are commonly used at large outdoor events like concerts, festivals or carnivals.
Every day, toilets use 141 billion liters of water to flush waste, so scientists try to make toilets that do not need so much water. In 2019, one group made a chemical to put onto toilets to make them very slippery so that the waste flushes away with only a little water. The scientists hope their invention will be used by many people one day.
Stegosaurus
Stegosaurus (meaning "roof-lizard") was a type of plant-eating dinosaur which lived in what is now western North America.
"Stegosaurus" lived in the Upper Jurassic period around 155 to 145 million years ago. It is one of the most easily recognized dinosaurs, with its distinctive double row of kite-shaped plates on its back, and the long spikes on its tail. The armor was necessary as it lived with such meat-eaters as "Allosaurus" and "Ceratosaurus".
"Stegosaurus" was originally named by Othniel Charles Marsh in 1877, from fossils found near Morrison, Colorado. These first bones became the first species of Stegosaur named: "Stegosaurus armatus".
Several different "Stegosaurus" species have been found.
"Stegosaurus" was the largest stegosaur, reaching up to 12 m (39.4 ft) in length and weighing up to 5,000 kg (5.5 short tons). However, 7 to 9 m was a more usual length.
The skull of "Stegosaurus" was long and narrow. Because of its short front legs, its head was close to the ground, probably no higher than 1 m (3.3 ft). It ate low-growing plants because of this. It had no front teeth, but it did have a horn-covered beak. Stegosaurian chewing teeth were small and triangular and did little grinding as they lacked wear surfaces.
Unlike most dinosaurs, it did not have a lacuna (hole) in its skull between the nose and eye.