A Heart Attack on the Inside

Written by Science Knowledge on 3:58 AM

As you’ve learned, heart-attack symptoms can be vague and misleading. But inside your body, the situation is more straightforward.

The trouble develops over many years as tiny growths form on the inside walls of the arteries that supply the heart, causing the arteries to narrow significantly. These growths, called plaque, hold small deposits of fat. For reasons that aren’t fully understood, some of these growths eventually become soft, inflamed, and ready to burst.

When one of these soggy problem spots tears open, it triggers an inflammatory reaction that causes your blood to form a clot. This clot seals the artery shut, in much the same way that it patches minor nicks and cuts in your skin. The result is that your heart is deprived of blood and starved of oxygen. The heart muscle begins to die.

Blood clots don’t just trigger heart attacks. A blood clot that forms elsewhere in your body can break off and travel through your blood, eventually becoming lodged in a smaller passageway. Depending on where the clot is, it can cut off the blood flow to other organs and damage them. A clot can even block the arteries that feed your brain, triggering a sudden loss of brain function called a stroke.

Don’t make the mistake of assuming that discomfort needs to be continuous to be serious. Heart-attack symptoms may come and go intermittently, as the arteryobstructing clot breaks up slightly and reforms—but the danger is the same.

For some reason, many people have the unspoken belief that 911 is the number to call when someone else is in trouble—usually, someone who’s already incapacitated (say, by a gunshot wound, a massive injury, or a Hollywood heart attack). But if you experience the symptoms of a heart attack, you have two choices: Swallow your pride or be embarrassed to death.

Source of Information : Oreilly - Your Body Missing Manual

Your Heart Attack

Written by Science Knowledge on 2:56 AM

Hopefully, you’ll never suffer a heart attack (at least not until you’re good and ready, say with an age in the triple digits). But if your heart does run into unexpected trouble, it’s essential that you recognize the symptoms and get help as quickly as possible.

An average heart attack may start modestly. Perhaps you’ve spent the day at the gym, and several hours later, you notice an unexpected tightness in your chest. Or you’re driving home from an absolutely ordinary day at work, but feeling a nagging, uncomfortable shortness of breath. Whatever the problem, it’s difficult to ignore—in fact, you feel thoroughly awful. You might also have aches, extreme fatigue, intermittent nausea, and sweating. But no matter what specific symptoms you experience, the one overriding characteristic of a heart attack is profound discomfort, not the clear-cut agony of a Hollywood heart attack.

During a heart attack, you may feel pain in a seemingly unrelated place, such as your back, neck, jaw, or arm (on either side). This phenomenon, called referred pain, happens when sensory messages from your heart get scrambled across nearby nerves, which are connected to a completely different body part. As a result, your brain gets the wrong message. (Referred pain is also responsible for the ache that appears to originate from a limb that’s been amputated, and the “brain-freeze” feeling of drinking a 1-liter slush drink in 60 seconds.)

In the midst of a heart attack, people often make two mistakes:

• They try to rest it off. Although the discomfort of a heart attack doesn’t go away, many people try to explain it as the fallout from a sudden flu, an overly enthusiastic workout, or a basket of bad clams. Eventually, it becomes obvious that these explanations don’t fit—but not before valuable time has ticked away.

• They go to the hospital without an ambulance. Most people are far too embarrassed to call 911 if they’re still conscious and able to move. Instead, they get a family member to drive them to the hospital. Or they call a taxi. Or they walk on their own. All the while, oxygen deprivation is slowly destroying their heart.

If you want to survive a heart attack, the right response is clear: Don’t worry about being alarmist. Don’t hope that the problem clears up with a bit of rest or wishful thinking. Don’t talk yourself into the average 110-minute waiting period. Instead, risk embarrassment and call an ambulance. As cardiologists say, time is muscle. The more minutes you waste, the more heart tissue you sacrifice—forever.

As you wait for the ambulance, it’s a good idea to chew an aspirin tablet, which can thin your blood and reduce the chance of severe heart damage. (You need to chew the aspirin to allow it to enter your blood quickly. Otherwise, you won’t see much action for hours.) However, avoid the aspirinchewing trick if you suspect another problem (like internal bleeding), in which case a blood-thinning drug may do more harm than good.

When you get to the hospital, modern medicine has several nearly miraculous treatments that can save your life. Clot-busting drugs can dissolve blockages, and an emergency surgery technique, called angioplasty, can dislodge obstructions and open arteries using a tiny, inflatable balloon.

Source of Information : Oreilly - Your Body Missing Manual

Veins and Arteries: Your Body’s Plumbing

Written by Science Knowledge on 2:51 AM

Blood travels through two types of passages. Oxygen-rich blood travels from your heart to the rest of your body through arteries (arteries move blood away from your heart). Oxygen-depleted blood makes the return trip back to your heart in veins. Together, arteries and veins are called blood vessels, and their winding tubes stretch tens of thousands of miles. Arteries are more than just passive tubes. Healthy arteries are strong, flexible, and lined with muscle. As your heart pumps blood, your arteries expand and contract rhythmically to help move that blood along. Veins are more passive—they transport blood steadily rather than pumping it in time with each heartbeat. Tiny valves prevent blood from seeping backward, and normal muscular activity helps it flow forward (which is why getting up and walking around helps your circulation). Varicose veins occur when the valves in the veins weaken and blood becomes trapped. The condition is mostly harmless, but sometimes uncomfortable.

To better understand how your arteries and veins work, it helps to take a trip through them yourself. You can start at the pump that keeps the traffic flowing—your heart.

1. Inject yourself into the right side of your heart (which is on the left side of the front-facing picture on this page). The blood that arrives here is the dark, purplish kind that has little oxygen left in it. With a forceful contraction, your heart squeezes itself together and propels your blood toward your lungs.

2. As your blood moves through the tiny blood vessels that line your lungs, it releases carbon dioxide and picks up a full cargo of oxygen. New blood keeps arriving, driving the oxygen-filled blood back to your heart.

3. When your blood reaches your heart a second time, it enters the left side (on the right side of the diagram). Your heart contracts again, pushing this oxygen-rich blood out through the aorta, which is the largest artery in your body.

4. As blood flows through your arteries, it moves through smaller and smaller passageways, eventually flowing into a microscopic network of capillaries, which are the tiniest blood vessels in your body. Nutrients and oxygen pass through the walls of these capillaries into neighboring cells.

5. Having completed its nutrient and oxygen delivery, your blood picks up waste products (carbon dioxide and so on) and is ready to return to the heart. Eventually, the capillaries join back together to form tiny veins. These tiny veins combine to create larger veins, and they eventually unite in the massive vena cava veins that lead back to the right side of your heart, and back to step 1.

Your blood makes this journey continuously, travelling from your heart to your lungs, back to your heart, through your body, and then back to your heart once more. Despite the winding route, each drop of blood makes the full circuit in less than 60 seconds.

Contrary to what you might expect, your veins don’t reclaim all the fluid your arteries release. Instead, a small amount lingers in your cells, and is collected into another system of tiny passageways, collectively called the lymph system. The lymph system is primarily known as a part of your immune system. To fight infection, it filters lymph fluid through small, bean-shaped lymph nodes that are scattered throughout your body. The lymph nodes store heavy reserves of white blood cells that destroy any invaders.

Source of Information : Oreilly - Your Body Missing Manual

Understanding Blood Types

Written by Science Knowledge on 2:47 AM

You’ve probably heard that each person’s blood can be classified according to blood type. The term refers to a relatively minor characteristic of blood—specifically, the types of proteins that stud the surface of your red blood cells. This detail is important because
it influences how your immune system differentiates friendly blood cells from potential enemies. If your immune system discovers red blood cells that don’t match its expectations, it’s likely to destroy them.

Usually, there’s little reason to spend time thinking about your blood type. But it becomes critically important in one situation—if you lose a lot of blood and need to be topped up with someone else’s. In this situation, the donor’s blood type needs to be compatible with yours, or your body will launch a dangerous, debilitating war against the new blood cells.

More rarely, blood-type issues can occur during pregnancy. In some cases, an unborn child inherits a blood type from the father that’s incompatible with the mother’s. This in itself doesn’t pose a problem, but when the mother is exposed to this blood (typically during delivery), her immune system may begin building antibodies that can destroy the foreign blood cells. Because these antibodies linger in her blood forever—they’re essentially a stockpile of on-reserve weapons—they can cause problems for future babies in future pregnancies. Fortunately, modern medicine deals painlessly with this issue: Early in pregnancy, mothers are given a blood test and, if necessary, a vaccine that prevents the production of these antibodies.

Source of Information : Oreilly - Your Body Missing Manual

The Contents of Blood

Written by Science Knowledge on 2:44 AM

The traffic that flows along the passages of your circulatory system is blood. If you’re an average person, you have about 6 quarts of blood perpetually circulating through your body. (In soft-drink terms, your body has 16 Coke cans’ worth of blood in it.)

We usually think of blood as a runny, red substance. However, if you broke blood down to its basic components, you’d start with a straw-colored liquid called plasma, which consists of water, dissolved nutrients, and a few other ingredients you’ll learn about in a moment. The red color of blood comes from the oxygen-carrying red blood cells.

Despite popular lore, blood is never blue (even when it’s inside your body, and even in royalty). When your blood is fully stocked up with oxygen, it’s bright red. Oxygen-depleted blood turns a purple-tinged, dark-red color. Due to the way your skin refracts light, your veins may look blue, but the blood inside is always some shade of red.

Your blood’s complex cocktail of substances includes:

• Oxygen and sugar. Your circulatory system delivers the essential nutrients and fuel every cell in your body needs to produce energy.

• Waste products. Your circulatory system takes potentially poisonous substances from the cells that excrete them to their appropriate disposal site. For example, it carries carbon dioxide to your lungs and delivers other toxins to your kidneys and liver.

• Hormones. These signaling chemicals let one body part influence another in ways both subtle and profound, and they travel from source to destination through your blood. Often, your brain starts the cascade of hormone release. (For example, to trigger your fight-or-flight response, your body uses hormones that speed up your heart, dilate your pupils, and constrict your blood vessels. On a much more extended timescale, your body releases growth hormones that reshape your body and start the changes of puberty.)

• Germ fighters. Your blood is the battleground on which your immune system confronts bacteria, viruses, and tumors.

• Clotting compounds. Your blood is precious stuff. Fortunately, it has its own loss-prevention system: platelets that plug holes in your skin, and a tough protein called fibrin that forms a reinforcing mesh around the platelets. Together, these compounds prevent your entire blood supply from draining out of a minor cut.

Source of Information : Oreilly - Your Body Missing Manual


About Me

In its broadest sense, science (from the Latin scientia, meaning "knowledge") refers to any systematic knowledge or practice. In its more usual restricted sense, science refers to a system of acquiring knowledge based on scientific method, as well as to the organized body of knowledge gained through such research.

Fields of science are commonly classified along two major lines: natural sciences, which study natural phenomena (including biological life), and social sciences, which study human behavior and societies. These groupings are empirical sciences, which means the knowledge must be based on observable phenomena and capable of being experimented for its validity by other researchers working under the same conditions.


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