Dental floss is a special type of thread. It is used for cleaning spaces between teeth which cannot be reached by toothbrushes. It is important to floss before brushing teeth and to floss at least once a day. Tooth brushing will not clean food that is packed between teeth. This 'food packing' can lead to unhealthy teeth and gums. Bacteria grow in this 'packed food' between teeth. These bacteria cause the surface of teeth (enamel) to break down. Then the teeth and gums and sometimes even the jaw can become seriously diseased.
These bacteria that come from the food on the teeth and between the teeth are called "plaque" or "bacterial plaque" and also can cause the gums to become less healthy. "Gingivitis" which means gum disease is one type of disease that flossing helps to prevent. Very serious diseases can start on the teeth and move to the bone of the jaw, damaging the jaw badly. Flossing your teeth reduces the danger of these serious diseases of the jaw bone. These hard-to-cure jaw bone diseases are called "periodontal disease".
Food that is trapped between the teeth can be uncomfortable and even cause pain. Some food is hard, for example meat, apple. Ground meat is soft and so is apple sauce. Chicken and turkey meat are hard and full of fibres and very often get trapped between the teeth. When hard food is trapped between the teeth it can cause discomfort and sometimes pain. When hard food is pressed by the teeth against the gum it can cause pain. Some people use toothpicks to try to remove trapped food from between the teeth and other people use dental floss to do this.
Dental floss can do most things that a toothpick can do but dental floss is much thinner than a toothpick and can thus get to places that most toothpicks cannot reach. So floss presumably does a better job at getting bits of food out from between the teeth, relieving discomfort and pain quicker.
When a person first starts flossing, bleeding can happen. This is normal and happens because teeth and gums that are not flossed are less healthy. It will stop as the teeth and gums get healthier with flossing.
Rickets
Rickets is a disease that happens in young children. It happens in children who do not get enough vitamin D and calcium. It causes larger spaces inside bones, and makes them dry, like sponges. It can make the legs curve toward each other (so the knees touch) or away from each other.
Rickets in adults is called osteomalacia.
The word "rickets" comes from the Greek word "rhakhis", which means "spine."
People need both vitamin D and calcium to make their bones strong.
Vitamin D helps the bones absorb (take up) calcium. Low vitamin D makes it hard to absorb calcium.
The human body makes vitamin D in the skin, from cholesterol. Then the liver changes vitamin D into calcitriol, which sends calcium from the blood into the bones. The bones need calcium to stay strong. However, the skin will not make vitamin D unless enough ultraviolet light shines on it. Sunlight contains ultraviolet light, so getting enough sun is one way of getting enough D.
People need calcium for calcification. Calcification uses calcium to help make bones bigger and stronger. Low calcium makes bones delicate and easier to break.
Rickets can be prevented if a person gets plenty of calcium and vitamin D.
The best way to do this is to get a lot of sunlight, and eat foods that have a lot of vitamin D and calcium in them. However, people who cannot get enough vitamin D and calcium this way can take supplements (vitamin pills that have calcium and vitamin D in them).
Foods that have a lot of calcium in them include:
Calcium is absorbed best by the bones when it is taken in amounts of 500 600 grams or less. Because of this, doctors suggest eating smaller amounts of foods with calcium in them, at different times in the day, instead of all at once.
There are three ways to get vitamin D: sunlight, foods, or supplements (vitamin pills that have vitamin D in them). However, many people cannot get enough vitamin D just from their diet.
There are only a few foods that have a lot of vitamin D in them. They include:
Breast milk may not have enough vitamin D in it to prevent rickets. Babies who are only breastfed, and not fed any other foods, may be given vitamin D drops to make sure they do not get rickets. However, this is not a significant risk if mothers and child have some exposure to sunlight. Children with dark skin are more likely to need additional vitamin D.
These things make a person more likely to get rickets:
Signs and symptoms of rickets include:
Bile
Bile or gall is a green-yellow fluid. It is secreted from the liver of most vertebrate animals, and is often stored in the gall bladder. Bile helps digest fat.
The components of bile are
The name "gall" comes from the Greek word "cholè" meaning green or yellow.
The term cholesterol and the illness cholera were named after gall.
Bile is also stored in bile ducts. Often after liver transplants, bile comes out of the body.
Dental pulp
The dental pulp is the part in the center of a tooth. It is made up of living soft tissue and cells. It is surrounded by dentine and contains nerves and blood vessels.
Protoplasm
Protoplasm is an old term, which means the living substance that makes up a cell. It is no longer much used. Biologists prefer to talk about the cytoplasm and the cell nucleus.
In plant cells, it is surrounded by a cell wall. In animal cells, the whole cell is made of protoplasm, surrounded by a cell membrane. Protoplasm in living beings is made up of about 7580% water. However, this is rather misleading because the cytoplasm is full of structures called organelles, which do various tasks. The endoplasmic reticulum is the largest of these structures; there are many other organelles.
The word "protoplasm" was first used in 1846 by Hugo von Mohl to describe the substance in plant cells, apart from the cell wall, the cell nucleus and the vacuole. After the invention of the electron microscope it was clear that a living cell is much more complicated than von Mohl knew.
Amylase
Amylase is an enzyme which breaks down starch into sugars which the body can use.
More accurately, it is a family of similar enzymes which work in a wide range of animals, plants and fungi. There are two variants in humans: alpha-amylase, and gamma-amylase.
Alpha-amylase is a major digestive enzyme. Its optimum pH is 6.7–7.0. It is found in saliva and pancreatic juice. It takes starch chains and breaks them into smaller pieces with two or three glucose units. It can break down starch into maltose. It works in the mouth and stomach during digestion.
The gamma-amylase has most acidic optimum pH of all amylases because it is most active around pH 3. Therefore, it works best in the stomach, which does have an acidic pH.
Apparently, early humans did not possess salivary amylase. The closest evolutionary relatives of humans, chimpanzees and bonobos, have either one or no copies of the gene for producing salivary amylase. A duplication event of the AMY1 gene led to the production of amylase in the saliva. The same event occurred independently in rodents. This shows the importance of salivary amylase in organisms that eat relatively large amounts of starch.
Carbohydrates are a food source rich in energy. After the agricultural revolution, human diet began to rely more on plant and animal domestication in place of hunting and gathering. This shift marked the beginning of a diet composed of 49% carbohydrates as opposed to the previous 35% observed in Paleolithic humans. As such, starch became a staple of human diet. Humans that contained amylase in the saliva would benefit from increased ability to digest starch more efficiently and in higher quantities.