Valve

in biology a piece of tissue attached to the wall of a tube that ensures the flow of blood is in one direction. The most important valves are the ones found in the HEART and VEINS, which prevent a backflow of blood. In engineering, valves are used in a similar way, to control the flow of fluids through pipes.

Taken from Dictionary of Science

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A valve is a device that regulates the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically pipe fittings, but are usually discussed as a separate category. In an open valve, fluid flows in a direction from higher pressure to lower pressure.

Valves are also found in the human body. For example, there are several heart valves which control the flow of blood in the chambers of the heart and maintain the correct pumping action.

Valves are used in a variety of contexts, including industrial, military, commercial, residential, and transportation.

The industries in which the majority of valves are used are oil and gas, power generation, mining, water reticulation, sewerage and chemical manufacturing.

Plumbing valves, such as taps for hot and cold tap water are the most noticeable types of valves. Other valves encountered on a daily basis include gas control valves on cookers, small valves fitted to washing machines and dishwashers, and safety devices fitted to hot water systems.

Valves may be operated manually, either by a hand wheel, lever or pedal. Valves may also be automatic, driven by changes in pressure, temperature, or flow. These changes may act upon a diaphragm or a piston which in turn activates the valve, examples of this type of valve found commonly are safety valves fitted to hot water systems or boilers.

More complex control systems using valves requiring automatic control based on an external input (i.e., regulating flow through a pipe to a changing set point) require an actuator. An actuator will stroke the valve depending on its input and set-up, allowing the valve to be positioned accurately, and allowing control over a variety of requirements.

Valves are also found in the Otto cycle (internal combustion) engines driven by a camshaft, tappets or push rods where they play a major role in engine cycle control.

Taken from Wikipedia

T-cell

a type of white blood cell (LYMPHOCYTE) that forms in the bone marrow and moves to the thymus gland, situated in the thorax. There are a whole variety of T-cells involved in recognizing particular foreign bodies (ANTIGENS), and they are important in fighting viral infections and destroying bacteria that have penetrated the cells of the body.

Taken from Dictionary of Science

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T cells or T lymphocytes belong to a group of white blood cells known as lymphocytes, and play a central role in cell-mediated immunity. They can be distinguished from other lymphocyte types, such as B cells and natural killer cells by the presence of a special receptor on their cell surface called T cell receptors (TCR). The abbreviation T, in T cell, stands for thymus, since this is the principal organ responsible for the T cell's maturation. Several different subsets of T cells have been discovered, each with a distinct function.

Taken from Wikipedia

Haemophilia

a genetic disorder affecting the blood, in which the lack of a vital BLOOD CLOTTING factor causes abnormally delayed clotting. Haemophilia usually occurs only in males, who receive the defective gene from their mothers. A haemophilic female can only arise if a haemophilic male marries a female carrying the gene (extremely rare). There is no known cure for haemophilia, and, when injured, haemophiliacs must rely on blood transfusion to replace the blood loss, which is considerably greater than that lost by a normal individual.

Taken from Dictionary of Science

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Haemophilia (also spelled hemophilia in North America, from the Greek haima αἷμα 'blood' and philia φιλος 'friend') is a group of hereditary genetic disorders that impair the body's ability to control blood clotting or coagulation, which is used to stop bleeding when a blood vessel is broken. Haemophilia A (clotting factor VIII deficiency) is the most common form of the disorder, occurring at about 1 in 5,000–10,000 male births. Haemophilia B (factor IX deficiency) occurs at about 1 in about 20,000–34,000 male births.

Similarly to most recessive sex-linked, X chromosome disorders, only males exhibit symptoms. This is due to the fact that females have two X chromosomes while males have only one, lacking a 'back up' copy for the defective gene the defective gene becomes manifest more easily in males. Because females have two X chromosomes and because haemophilia is rare, the chance of a female having two defective copies of the gene is very low, thus females are almost exclusively asymptomatic carriers of the disorder. Female carriers may inherit the defective gene from either their mother, father, or it may be a new mutation. Only under rare circumstances do females actually have haemophilia.

Haemophilia lowers blood plasma clotting factor levels of the coagulation factors needed for a normal clotting process. Thus when a blood vessel is injured, a temporary scab does form, but the missing coagulation factors prevent fibrin formation, which is necessary to maintain the blood clot. Thus a haemophiliac does not bleed more intensely than a normal person, but can bleed for a much longer amount of time. In severe haemophiliacs even a minor injury could result in blood loss lasting days, weeks, or not ever healing completely. In areas such as the brain or inside joints, this can be fatal or permanently debilitating.

Taken from Wikipedia

Haemoglobin

an iron-containing red pigment, which is found within the red blood cells (called ERYTHROCYTES) of vertebrates and which is responsible for the transport of oxygen around the body. In actively metabolizing tissue such as the muscles, haemoglobin exchanges oxygen for carbon dioxide (CO₂), which is then carried in the blood back to the heart and pumped to the lungs, where the haemoglobin loses the CO₂ and regains oxygen.

Taken from Dictionary of Science

Macrophage

a special type of cell that forms part of the IMMUNE SYSTEM of vertebrates. Macrophages are derived from MONOCYTES in the blood system and can move to infected or inflamed areas of the body using PSEUDOPODIA. In these areas, they surround, engulf and degrade broken cells and other debris, including microbes, by means of the process called PHAGOCYTOSIS.

Taken from Dictionary of Science

Jaundice

a condition characterized by the unusual presence of bile pigment circulating in the blood. Jaundice is caused by the bile produced in the liver, which should go into the intestines, passing instead into the circulation because of some obstruction. The symptoms of jaundice include a yellowing of the skin and the whites of the eyes.

Taken from Dictionary of Science

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Jaundice, also known as icterus (attributive adjective: icteric), is a yellowish discoloration of the skin, the conjunctival membranes over the sclerae (whites of the eyes), and other mucous membranes caused by hyperbilirubinemia (increased levels of bilirubin in the blood). This hyperbilirubinemia subsequently causes increased levels of bilirubin in the extracellular fluids. Typically, the concentration of bilirubin in the plasma must exceed 1.5 mg/dL, three times the usual value of approximately 0.5 mg/dL, for the coloration to be easily visible. Jaundice comes from the French word jaune, meaning yellow.

One of the first tissues to change color as bilirubin levels rise in jaundice is the conjunctiva of the eye, a condition sometimes referred to as scleral icterus. However, the sclera themselves are not "icteric" (stained with bile pigment) but rather the conjunctival membranes that overlie them. The yellowing of the "white of the eye" is thus more properly conjunctival icterus.

Taken from Wikipedia

'MY FATHER DOESN'T LOVE ME: WHAT DO I DO?'

Families full of emotional pain and anger seem to be everywhere. If you are in one, here's what you can do.

By David Fraser

"By the time he was through with me, I was spitting blood all over the ground and blood covered the front of my T-shirt.How am I supposed to forget that?"

How indeed?

Later that evening, as I thought over the memories this young man had of being physically and emotionally abused by his stepfather, I couldn't help being overwhelmed by sadness. He was a big-hearted guy, with great potential, yet he was emotionally chained to the past, to the whirlpool of pain, anger and violence that had engulfed his teen years.

As many of you well know, he is not alone. Millions of homes are plagued with pain and anger.

Here is a sampling of letters we've received:

"I've got a big problem I don't know how to solve. My dad hates me. I try so hard to please him, but no matter what I do, there's always something wrong with it. I can't sit down and talk with him because he'll get really mad.... Please help me."

"I have a problem that is troubling me night and day. It's with my parents. When they get mad at me, they call me hurtful names, curse words and awful things I wouldn't repeat. [My parents] yell at me every day, so I cry either inwardly but usually outwardly.... My parents hate me! What can I do?"

"I'm a deaf teenager but my parents don't care about me. My dad told me when I finish high school he's going to kick me and my things out of the house. I don't know what I can do to tell them I love them and that I don't really hate them. Can you help before it goes farther down the hole?"

Some bad solutions

If you're now living in a 'toxic' family, you're probably feeling pain. And pain produces anger. Lots of it. Chances are you may wake up angry and go to bed angry.

If you're a girl, you probably find yourself crying a lot. If you're a guy, you're probably getting more and more aggressive toward whoever is causing your pain, even toward people who are not responsible. (Psychologists call this displaced anger.) One thing's for sure, you're not happy.

There are solutions, both good and bad. First let's talk about some bad solutions. When we're in pain we try to do something about it. If somebody is causing you pain, you often attack or withdraw.

This leads some teens into pretty bad coping mechanisms. Guys and some girls will find themselves verbally abusing the parent that is causing the pain. (Often that parent is the father.) Sometimes they will start retaliating physically.

The opposite approach is withdrawal. Withdrawal can take a number of forms. Drugs, alcohol and sexual intimacy may seem to provide relief from the pain. Some teens run away from home. Others attempt suicide. Sad to say, some succeed.

If you're in pain, you may have tried one or more of these solutions already. They are all bad. After the drugs, alcohol, sex and outbursts of anger, the pain remains. These solutions really solve nothing at all.

So what do you do?

Breaking down the barriers and trying to communicate can be hard. But it's worth the effort.

• Reach out for help. When we're having difficult times, we all need help. It's important to get help from the right people.

Teens often want sympathy from their friends. Often they get it. But that's all they get. Teens rarely have the resources and maturity to constructively help their friends through serious personal difficulties.

If you are in an abusive home, get help from a family member, a teacher or a minister you trust. Don't stop until you find someone who will listen. (Most phone books have child abuse hotlines that can help you.)

But when the danger is gone, the anger remains. In many cases physical abuse is not involved, but teens still feel unloved, unwanted or even hated. These teens often also feel anger. Overcoming that anger and hurt is our concern here.

• Reach out to your father (or mother). Sure, this is tough. But you need to ask yourself some tough questions. How do you know he doesn't love you? Maybe he's been trying to re4each out to you, but he doesn't know how and you can't see it because you've built a wall around yourself.

Parents and teens can get caught in a downward spiral of pain and anger and fail to notice when one is trying to break the spiral. You have to do your part.

Many years ago, Jesus Christ, the one who created and who best understands the human mind, said we should love those who make life difficult for us (Matthew 5:44). That was, and is, totally practical advice, because love removes hate and anger. And hate and anger make you unhappy.

Reaching out is how you start loving your father. It means thinking about how to make his life more pleasant, not more painful.

Sometimes we think we're the only ones with problems. But parents have problems also: financial problems, job problems, health problems. And they have feelings too!

What can you do to start making your parents' lives a little easier? There are a thousand things you could do to help, if you put some creative thought into it. And in the process of helping, you start becoming happier.

It's not easy. It's easier to get angry and stomp out the door. It's easier to get drunk or stoned. But then, that doesn't make you happy, does it?

Until you realize that you choose your emotions -- that you can choose to love or hate, to be angry or happy -- nothing will fundamentally change in your life. The downward spiral will continue.

And how many times do you keep on trying to reach out? When asked that question Christ replied "seventy times seven" (Matthew 18:22). That's 490 times! In other words you can't ever stop showing love.

• Reach out to your Father in heaven. What if your best efforts come to nothing? There are some parents who are so emotionally crippled that they can't respond to their teen's attempts to break the barriers of bitterness.

But pity, not anger, is the response of love. You must keep on trying to reach out to your father. You also have to be realistic. At this point, he may be incapable of love.

The Creator of life and love is always loving, though. You're not too young to start adding a spiritual dimension to your life. When he was only 12, Jesus explained to his stepfather that he already had a close relationship with his Father in heaven (Luke 2:49). The Creator wants to have the same relationship with you.

He wants to love you and help you the way no human father ever can.

He may seem distant, but in reality he is "not far from every one of us" (Acts 17:27), if we want to reach out and make contact with him.

You may feel like you're in a hole right now. But you can start pulling yourself out. There are solutions. But you must choose the way up.

Taken from Youth 90 magazine