Wednesday, February 24, 2010


The heart weighs between 7 and 15 ounces (200 to 425 grams) and is a little larger than the size of your fist. By the end of a long life, a person's heart may have beat (expanded and contracted) more than 3.5 billion times. In fact, each day, the average heart beats 100,000 times, pumping about 2,000 gallons (7,571 liters) of blood.

Anatomy of the Heart

Your heart is located between your lungs in the middle of your chest, behind and slightly to the left of your breastbone (sternum). A double-layered membrane called the pericardium surrounds your heart like a sac. The outer layer of the pericardium surrounds the roots of your heart's major blood vessels and is attached by ligaments to your spinal column, diaphragm, and other parts of your body. The inner layer of the pericardium is attached to the heart muscle. A coating of fluid separates the two layers of membrane, letting the heart move as it beats, yet still be attached to your body.

Your heart has 4 chambers. The upper chambers are called the left and right atria, and the lower chambers are called the left and right ventricles. A wall of muscle called the septum separates the left and right atria and the left and right ventricles. The left ventricle is the largest and strongest chamber in your heart. The left ventricle's chamber walls are only about a half-inch thick, but they have enough force to push blood through the aortic valve and into your body.

The Heart Valves

Four types of valves regulate blood flow through your heart:

  • The tricuspid valve regulates blood flow between the right atrium and right ventricle.
  • The pulmonary valve controls blood flow from the right ventricle into the pulmonary arteries, which carry blood to your lungs to pick up oxygen.
  • The mitral valve lets oxygen-rich blood from your lungs pass from the left atrium into the left ventricle.
  • The aortic valve opens the way for oxygen-rich blood to pass from the left ventricle into the aorta, your body's largest artery, where it is delivered to the rest of your body.

Friday, February 12, 2010

Tuesday, February 2, 2010


Side Effects of Smoking Cigarettes
  1. The mixture of nicotine and carbon monoxide in each cigarette you smoke temporarily increases your heart rate and blood pressure, straining your heart and blood vessels.
  2. This can cause heart attacks and stroke. It slows your blood flow, cutting off oxygen to your feet and hands. Some smokers end up having their limbs
  3. Tar coats your lungs like soot in a chimney and causes cancer. A 20-a-day smoker breathes in up to a full cup (210 g) of tar in a year.
  4. Carbon monoxide robs your muscles, brain and body tissue of oxygen, making your whole body and especially your heart work harder. Over time, your airways swell up and let less air into your lungs.
  5. Smoking causes disease and is a slow way to die. The strain of smoking effects on the body often causes years of suffering. Emphysema is an illness that slowly rots your lungs. People with emphysema often get bronchitis again and again, and suffer lung and heart failure.
  6. Lung cancer from smoking is caused by the tar in tobacco smoke. Men who smoke are ten times more likely to die from lung cancer than non-smokers.
  7. Smoking causes fat deposits to narrow and block blood vessels which leads to heart attack.
  8. Cigarette smoking during pregnancy increases the risk of low birth weight, prematurity, spontaneous abortion, and perinatal mortality in humans, which has been referred to as the fetal tobacco syndrome.


Medical researchers use laboratory-grown human cells to learn the intricacies of how cells work and test theories about the causes and treatment of diseases. The cell lines they need are “immortal”—they can grow indefinitely, be frozen for decades, divided into different batches and shared among scientists. In 1951, a scientist at Johns Hopkins Hospital in Baltimore, Maryland, created the first immortal human cell line with a tissue sample taken from a young black woman with cervical cancer. Those cells, called HeLa cells, quickly became invaluable to medical research—though their donor remained a mystery for decades. In her new book, The Immortal Life of Henrietta Lacks, journalist Rebecca Skloot tracks down the story of the source of the amazing HeLa cells, Henrietta Lacks, and documents the cell line's impact on both modern medicine and the Lacks family.

Who was Henrietta Lacks?
She was a black tobacco farmer from southern Virginia who got cervical cancer when she was 30. A doctor at Johns Hopkins took a piece of her tumor without telling her and sent it down the hall to scientists there who had been trying to grow tissues in culture for decades without success. No one knows why, but her cells never died.

Why are her cells so important?
Henrietta’s cells were the first immortal human cells ever grown in culture. They were essential to developing the polio vaccine. They went up in the first space missions to see what would happen to cells in zero gravity. Many scientific landmarks since then have used her cells, including cloning, gene mapping and in vitro fertilization.

There has been a lot of confusion over the years about the source of HeLa cells. Why?
When the cells were taken, they were given the code name HeLa, for the first two letters in Henrietta and Lacks. Today, anonymizing samples is a very important part of doing research on cells. But that wasn’t something doctors worried about much in the 1950s, so they weren’t terribly careful about her identity. When some members of the press got close to finding Henrietta’s family, the researcher who’d grown the cells made up a pseudonym—Helen Lane—to throw the media off track. Other pseudonyms, like Helen Larsen, eventually showed up, too. Her real name didn’t really leak out into the world until the 1970s.

How did you first get interested in this story?
I first learned about Henrietta in 1988. I was 16 and a student in a community college biology class. Everybody learns about these cells in basic biology, but what was unique about my situation was that my teacher actually knew Henrietta’s real name and that she was black. But that’s all he knew. The moment I heard about her, I became obsessed: Did she have any kids? What do they think about part of their mother being alive all these years after she died? Years later, when I started being interested in writing, one of the first stories I imagined myself writing was hers. But it wasn’t until I went to grad school that I thought about trying to track down her family.

How did you win the trust of Henrietta’s family?
Part of it was that I just wouldn’t go away and was determined to tell the story. It took almost a year even to convince Henrietta’s daughter, Deborah, to talk to me. I knew she was desperate to learn about her mother. So when I started doing my own research, I’d tell her everything I found. I went down to Clover, Virginia, where Henrietta was raised, and tracked down her cousins, then called Deborah and left these stories about Henrietta on her voice mail. Because part of what I was trying to convey to her was I wasn’t hiding anything, that we could learn about her mother together. After a year, finally she said, fine, let’s do this thing.

When did her family find out about Henrietta’s cells?
Twenty-five years after Henrietta died, a scientist discovered that many cell cultures thought to be from other tissue types, including breast and prostate cells, were in fact HeLa cells. It turned out that HeLa cells could float on dust particles in the air and travel on unwashed hands and contaminate other cultures. It became an enormous controversy. In the midst of that, one group of scientists tracked down Henrietta’s relatives to take some samples with hopes that they could use the family’s DNA to make a map of Henrietta’s genes so they could tell which cell cultures were HeLa and which weren’t, to begin straightening out the contamination problem.

So a postdoc called Henrietta’s husband one day. But he had a third-grade education and didn’t even know what a cell was. The way he understood the phone call was: “We’ve got your wife. She’s alive in a laboratory. We’ve been doing research on her for the last 25 years. And now we have to test your kids to see if they have cancer.” Which wasn’t what the researcher said at all. The scientists didn’t know that the family didn’t understand. From that point on, though, the family got sucked into this world of research they didn’t understand, and the cells, in a sense, took over their lives.

Monday, February 1, 2010


Echinoderm means "spiny skin."Echinodermata always starts from a larvae stage and has approximately 7000 described living species and about 13,000 extinct species known from the fossil record. This phylum is the largest without any freshwater or terrestrial forms. Mainly a marine group, echinoderms are found in all the oceans.
An internal skeleton is present throughout members of the phylum. The skeletal and muscular arrangement varies among groups but mostly RADIALLY SYMMETRICAL. It also has a poorly defined open circulatory system. The OSSICLES are calcareous plates buried in the fleshy region beneath the outer skin. This represents the endoskeletonwhich gives the body rigidity and support. Echinoderms in general are most vulnerable in their larval stage. As adults, asteroids have an anti-predator adaptation where they can lose an arm to a predator and the arm is later regenerated. Sea urchin eggs are also edible and often served in sushi bars. Echinodermata includes the starfish, sea urchins, brittle stars, sea cucumbers and feather stars.