Group items tagged

If you experience engine trouble, you take your car to a mechanic. If your pipes leak, you call a plumber. And if you fracture a leg, the usual course of action is to visit a doctor. But unlike other things that may break in life, bones begin healing on their own before you even set foot in a waiting room.The human body possesses amazing healing powers that enable it to bounce back from a vast array of illnesses and injuries. Sometimes broken bones can heal so thoroughly within a few months that even an x-ray can't determine the original fracture line.Doctors often play a vital, sometimes lifesaving, role in a bone's healing process. But, these experts basically help the body heal itself. Doctors provide optimal conditions for bone repair and healing to take place. The rest is up to your cells.But how does this amazing biological process work? How can a fractured limb grow back to its former strength? To understand, you first have to take a closer look at just what bones are made of and how alive they really are.

All blood enters the right side of the heart through two veins: The superior vena cava (SVC) and the inferior vena cava (IVC) (see figure 3).The SVC collects blood from the upper half of the body. The IVC collects blood from the lower half of the body. Blood leaves the SVC and the IVC and enters the right atrium (RA) (3).When the RA contracts, the blood goes through the tricuspid valve (4) and into the right ventricle (RV) (5). When the RV contracts, blood is pumped through the pulmonary valve (6), into the pulmonary artery (PA) (7) and into the lungs where it picks up oxygen.

There's a famous myth that the tongue is the body's strongest muscle. It's not really true -- and not by any definition of strength. But that shouldn't make the tongue any less impressive.

The tongue is an accessory digestive organ which, along with the cheeks, keeps food between the upper and lower teeth until it's sufficiently masticated, or chewed.

Have you ever opened the hood of your car and wondered what was going on in there? A car engine can look like a big confusing jumble of metal, tubes and wires to the uninitiated.

The reasons for our crying changes as we grow from babies to adults. Learn more on the next page.

In recent years, scientists have expanded the definition of taste, allowing one, and possibly two, primary tastes into the original canon of four -- sour, bitter, sweet and salty.

As an example, think of a person who has a cold. That person may cough into his or her hand and then touch a doorknob, thus placing the cold virus on that doorknob. The virus may die on the doorknob, but it's also possible that the next person to touch the doorknob will pick it up. If that person then touches food with the unwashed hand and consumes the food, the virus is now inside the body.

A day consists of two 12-hour periods, for a total of 24 hours. An hour consists of 60 minutes. A minute consists of 60 seconds. Seconds are subdivided on a decimal system into things like "hundredths of a second" or "millionths of a second."

hat's a pretty bizarre way to divide a day up. We divide it in half, then divide the halves by twelfths, then divide the twelfths into sixtieths, then divide by 60 again, and then convert to a decimal system for the smallest increments. It's no wonder children have trouble learning how to tell time.

How long is a day? It's the amount of time it takes for the Earth to rotate one time on its axis. But how long does it take the Earth to rotate? That is where things become completely arbitrary. The world has decided to standardize on the following increments: