An orange is a type of citrus fruit which people often eat. Oranges are a very good source of vitamins, especially vitamin C.[1]. Orange juice is an important part of many people's breakfast. The "sweet orange", which is the kind that are most often eaten today, grew first in Asia but now grows in many parts of the world.
Oranges are round orange-coloured fruit that grow on a tree
which can reach 10 metres high. Orange trees have dark green shiny
leaves and small white flowers with five petals. The flowers smell very
sweet which attracts many bees.
An orange has a tough shiny orange skin. Inside, the fruit is divided into "segments", which have thin tough skins that hold together many little sections with juice
inside. There are usually ten segments in an orange, but sometimes
there are more. Inside each segment of most types of orange there are seeds
called "pips". Orange trees can be grown from pips, but some types of
orange trees can only be grown from "cuttings" (a piece cut off a tree
and made to grow roots). The segments and the skin are separated by
white stringy fibrous material called "pith". In most types of oranges,
the skin can be peeled off the pith, and the segments can be pulled
apart with the fingers to be eaten. In some oranges it is hard to take
the skin off. With mandarin oranges, the skin, pith and segments can all
be pulled apart very easily. Orange skin is often called "orange peel".
Oranges are an important food source in many parts of the world for
several reasons. They are a commonly available source of vitamin C. The
juice is a refreshing drink. They last longer than many other fruits
when they are stored. They are easy to transport
because each orange comes in its own tough skin which acts as a
container. They can be piled into heaps or carried in bags, lunchboxes
and shipping containers without being easily damaged.
The colour orange takes its name from the fruit. The word "orange" is unusual because it is one of only a few English words that does not rhyme with anything.[2]
Vitamin C, also known as ascorbic acid, is found in fresh fruits, berries and green vegetables. It is one of the water soluble vitamins.
Vitamin C is important in wound healing. Lack of vitamin C can cause a sickness called scurvy, where the gums
in the mouth bleed easily and wounds do not heal. Lack of Vitamin C was
a serious health problem on long ocean trips where supplies of fresh
fruit were quickly used up. Many people died from scurvy on such trips.
Most animals make their own vitamin C. Some mammalian groups cannot. Those that cannot include the main suborder of primates, the Haplorrhini: tarsiers, monkeys and apes, including human beings. Others include bats, capybaras and guinea pigs.
Vitamin C was first found in 1928, and in 1932 it was proved to stop the sickness called scurvy.
Functions of vitamin C in the body
In living organisms, ascorbate is an antioxidant, since it protects the body against oxidative stress.[1] It is also a cofactor in at least eight enzymatic reactions, including several collagen synthesis reactions that cause the most severe symptoms of scurvy when they are dysfunctional.[2] In animals, these reactions are especially important in wound-healing and in preventing bleeding from capillaries.
- Vitamin C is needed for the production of collagen in the connective tissue. These fibres are in many places throughout the body; providing firm but flexible structure. Some tissues have a greater percentage of collagen, especially: skin, mucous membranes, teeth, and bones.
- Vitamin C is required for making of dopamine, noradrenaline, and adrenaline in the nervous system or in the adrenal glands.
- Vitamin C is also needed to make carnitine, important in the tranfer of energy to the cell mitochondria.
- It is a strong antioxidant.
- The tissues with greatest percentage of vitamin C—over 100 times the level in blood plasma—are the adrenal glands, pituitary, thymus, corpus luteum, and retina.
- The brain, spleen, lung, testicle, lymph nodes, liver, thyroid, small intestinal mucosa, leukocytes, pancreas, kidney, and salivary glands usually have 10 to 50 times the concentration present in plasma.
Vitamin C deficiency
Lack of ascorbic acid in the daily diet leads to a disease called scurvy, a form of avitaminosis that is characterized by:
- Loose teeth
- Superficial bleeding
- Fragility of blood vessels
- Poor healing
- Compromised immunity
- Mild anemia.
0 komentar:
Posting Komentar