let's introduce what is tears first before we get future...
[simple way] - tears, is a liquid produced by our body to clean and lubricate our eyes..
[future explanation]- lacrimation is used in a medical or literary sense to refer to crying...
there are three basic types of tears..
first: basal tears
~In healthy mamalia eyes, the cornea is continually kept wet and nourished by basal tears. They lubricate the eye, and help to keep it clear of dust. lysozyme,lactoferrin,lipocalin, Tear fluid contains water,mucin,lipids,lacritin,immunoglobulins,glucose,urea, sodium and potassium. Some of the substances in lacrimal fluid (such as lysozyme) fight against bacteria infectionas a part of the immune system. Lysozyme does this by dissolving the outer coating of certain bacteria. It is a typical body fluid with a salt content similar to blood plasma. Usually, in a 24-hour period, 0.75 to 1.1 grams (0.03-0.04 ounce avoirdupois) of tears are secreted; this rate slows with age.
second: reflex tears
~results from irritation of the eye by foreign particles, or from the presence of irritant substances such as onion vapors,tear gas or pepper spray in the eye's environment, including the cornea, conjunctiva, or nasal mucosa. It can also occur with bright light and hot or peppery stimuli to the tongue and mouth. It is also linked with vomiting. These reflex tears attempt to wash out irritants that may have come into contact with the eye.
third: crying or weep(psychic tears)
~generally referred to as crying or weeping, is increased lacrimation due to strong emotional stress, suffering, mourning or physical pain. This practice is not restricted to negative emotions; many people cry when extremely happy. In humans, emotional tears can be accompanied by reddening of the face and sobbing—cough-like, convulsive breathing, sometimes involving spasms of the whole upper body. Tears brought about by emotions have a different chemical make up than those for lubrication; emotional tears contain more of the protein-based hormones prolactin, adrenocorticotropic hormone , and leucin enkephalin (a natural painkiller) than basal or reflex tears. The limbic system is involved in production of basic emotional drives, such as anger, fear, etc. The limbic system, specifically the hypothalamus, also has a degree of control over the autonomic system. The parasympathetic branch of the autonomic system controls the lacrimal glands via the neurotransmitter acetylcholine through both the nicotinic and muscarinic receptors. When these receptors are activated, the lacrimal gland is stimulated to produce tears.
second: reflex tears
~results from irritation of the eye by foreign particles, or from the presence of irritant substances such as onion vapors,tear gas or pepper spray in the eye's environment, including the cornea, conjunctiva, or nasal mucosa. It can also occur with bright light and hot or peppery stimuli to the tongue and mouth. It is also linked with vomiting. These reflex tears attempt to wash out irritants that may have come into contact with the eye.
third: crying or weep(psychic tears)
~generally referred to as crying or weeping, is increased lacrimation due to strong emotional stress, suffering, mourning or physical pain. This practice is not restricted to negative emotions; many people cry when extremely happy. In humans, emotional tears can be accompanied by reddening of the face and sobbing—cough-like, convulsive breathing, sometimes involving spasms of the whole upper body. Tears brought about by emotions have a different chemical make up than those for lubrication; emotional tears contain more of the protein-based hormones prolactin, adrenocorticotropic hormone , and leucin enkephalin (a natural painkiller) than basal or reflex tears. The limbic system is involved in production of basic emotional drives, such as anger, fear, etc. The limbic system, specifically the hypothalamus, also has a degree of control over the autonomic system. The parasympathetic branch of the autonomic system controls the lacrimal glands via the neurotransmitter acetylcholine through both the nicotinic and muscarinic receptors. When these receptors are activated, the lacrimal gland is stimulated to produce tears.
if u lazy..
jz view the simplest form below..
Tears are a liquid made by the body to clean and lubricate the eyes.
There are three different types of tears that the body makes:
- Basal tears: In a normal, healthy mammal, tears are regularly made to clean the cornea (front part of the eye) and to keep it clean from dust.
- Reflex tears: This type of tear is made when something irritates the eye, say, bits of dust or the smell of an onion. These tears are made to clean the eye and wash out anything irritating it.
- Crying tears (physic): The last category is called crying or weeping, when tears are made because of physical pain or strong emotions. Most mammals make this type of tear simply out of pain. Humans are the only known mammals to cry as an emotional reaction. Some studies suggest that elephants and gorillas may do this, too.
you may have a look at this ...
ps : at first, i was thinking to write myself after i search for all the information..
bt.. my eyes too tired.. and i am lazy..
so i jz copy..
sorry for tht..
crying sometimes is good..
bt over crying may cause ur vision to be bad..
end of this topic ..
next topic? loves, i think..
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