1. Physiology

Category Archives: Physiology

So 2014 Is International Crystallography Year

Posted on by

Jonathan Nackstrand / AFP / Getty Images

Laureates arrive for the traditional Nobel Prize banquet at the Stockholm City Hall on December 10, 2013. In total, 28 Nobel prized discoveries have been associated with crystallography, among them this year's awards for Chemistry and Physics.

There once was a dark and distant time when we only understood molecules as equations of letters and numbers. With the advent of crystallography the science of how matter is arranged we learned how to visualize molecules in 3D, helping us make everything from better medicines to stronger materials. Despite that huge advance, if you stopped someone in the street and asked them what crystallography was, chances are you would get a blank stare. To help raise awareness, and to celebrate a century of amazing discoveries, UNESCO has declared 2014 to be the International Year of Crystallography. Heres a bluffers guide to the topic. 1. It starts with X-rays

Normally when you want to magnify things, you use a microscope. There is, however, a limit to the smallness of things you can see, namely the wavelength of the light youre using. Since visible light has a frequency of between roughly 400 and 700 nanometers, it is unable to detect atoms, which are separated by merely 0.1 nanometers. X-rays, on the other hand, have just the right frequency.

2. Crystals are used to create diffractions

Unfortunately, we dont have good enough lenses to produce x-ray microscopes capable of studying molecules. So scientists have to beam X-rays onto molecules, which shatter the rays, just as light is reflected when it hits any object. The shattered rays called the diffraction are then reassembled into an image by a computer program. But since the diffraction of a single molecule would be weak to the point of unintelligibility, scientists get the molecules theyre studying to clump together into crystal form. This highly ordered structure, made up of vast amounts of molecules, makes x-ray diffractions the main tool of crystallography easier to study.

3. So why chose 2014 for the International Year of Crystallography?

The International Year of Crystallography celebrates the centennial of the Nobel Prize of Max Von Laue, the first scientist to diffract x-rays with a crystal. However, the first person to solve a molecular structure that of NaCl, or table salt was the Brit William Lawrence Bragg. His equation to translate the diffraction into a structure, Braggs Law, is still in use today. In 1915, at age 25, he became the youngest Nobel laureate, when he jointly received the prize with his father William Henry Bragg. The Braggs went on to create a dynasty of groundbreaking crystallographers at the Cavendish Laboratory at the University of Cambridge.

This Royal Institute video describes the legacy of William Lawrence Bragg and his disciples:

4. Crystallography was crucial to one of the great discoveries of the 20th century

Originally posted here:
So 2014 Is International Crystallography Year

Frostbite Physiology: How Bitter Cold Can Freeze You Down To The Bone

Posted on by

As we previously explained in an exploration of the physiology of polar bear plunges, your body reacts to cold outside by constricting blood vessels close to your skin. This shunts blood away from your extremities and toward your core; its your bodys emergency measure to try and protect your vital organs. But this lack of blood flow comes at a cost -- it puts those affected tissues at greater risk for freezing and tissue damage.

In cold conditions -- even those slightly above zero -- frostbite can develop in half an hour or less. In extreme cases with cold and high winds, sometimes it can take even less time. The National Weather Service has a handy (and chilling) chart that illustrates the risk for frostbite based on temperature and wind speed:

Times to develop frostbite, calculated by the National Weather Service. NWS

With so many areas in the Midwest dipping into negative double-digit temperatures, even relatively easygoing winds of 5 or 10 miles an hour may drive frostbite danger zones down to 10 minutes or less. Even in New York City, which experienced a relatively balmy six degrees on Tuesday morning, people are at risk for developing frostbite within 30 to 45 minutes thanks to winds that are gusting up to 50 miles per hour.

Experts say that bundling up is the best protection.

"Prevention really is key," Cleveland Clinic emergency physician Seth Podolsky told NPR. "The more time and the more skin exposed, the worse it is.

Some of the signs of frostbite are skin with a white or grayish-yellow color, unusually firm or waxy skin, and numbness. Blisters and skin discoloration can follow. If your tissue actually freezes, that may lead to gangrene -- dead tissue -- treatable only by cutting away the affected areas.

If you are frostbitten, the best thing to do is to seek immediate medical attention. If you cant immediately get to the doctor, there are several steps that can be taken to mitigate the damage, via the the National Institutes of Health:

- Get into a warm room.

- Put the affected area in warm -- not hot! -- water, or warm using body heat (such as putting a frostbitten hand in your armpit).

Originally posted here:
Frostbite Physiology: How Bitter Cold Can Freeze You Down To The Bone

Clark College’s enrollment down from a year ago

Posted on by

A A

The stadium-style lecture hall was filled with students Monday, the first day of winter term in instructor Mark Bolke's anatomy and physiology class at Clark College.

The class a prerequisite for entrance into several popular health care programs, including nursing, dental hygiene and medical radiography remains as in-demand as ever, even as the college's overall enrollment for winter term has dropped.

The college has enrolled 12,578 students this term, a drop from the 13,477 students enrolled this time last year.

"We haven't dropped off within our department, at least," said Bolke, who's taught anatomy and physiology for the past 15 years. "We're sort of the exception here. We're still holding strong."

This winter, there are roughly 120 anatomy and physiology students spread across three classes, on par with previous years. Bolke teaches the class in one of the campus' two large lecture halls to accommodate all the students.

He has no trouble filling the seats.

"Anatomy and physiology classes are generally full," he said, adding there are currently about 10 students waiting for someone to drop the course so they can get in.

The reason for its popularity is simple, Bolke said: His students hope to enter a lucrative health care occupation.

Margie Baron, 17, said she's taking the class so she can successfully apply to nursing school. The large number of classmates, many of whom want to do the same thing, is an incentive for her to work hard and achieve high grades.

Read more from the original source:
Clark College's enrollment down from a year ago

Polar Bear Plunge Physiology: What A Cold Water Dip On New Year’s Day Does To Your Body

Posted on by

Cold water swimming enthusiasts love the rush that comes with a near-freezing dip. Anda polar bear plunge does do lots of things to make you feel invigorated, says Christopher Tedeschi, an emergency physician at Columbia University Medical Center. But from your bodys perspective, a racing heart and gasping breath signal not so much excitement as self-preservation.

It doesnt even take near-freezing water to provoke a physiological response anything under 70 degrees Fahrenheit can be considered cold, according to Tedeschi. Hypothermia wont set in unless you plan on floating around for around an hour, but your body will still react very quickly to a sudden immersion.

What happens in the first one to two minutes is what we call the cold shock response, Tedeschi says. Your body reacts by getting very revved up.

The first and most immediate sign of this metabolic turbo-drive can be seen in the respiratory system. As soon as a person rushes or jumps into frigid water, he begins taking big gasps of breath. If a person cant get his breathing under control, he might start to hyperventilate within a minute or so.

In those first few minutes, your core body temperature wont change very much, but your surface temperature will start to drop. Your body reacts to this by constricting blood vessels near the skin. Constricting these blood vessels is a way for your body to try and conserve all the warmth that it can by bringing warm blood towards the heart and brain -- to do so, it has to cut down on the blood flowing at the periphery of your body. (You can see the opposite effect on summer days, when your blood vessels dilate, transferring heat from your core out towards the skin, dissipating heat and giving you a nice rosy flush.) This blood vessel constriction also affects your nerves, which might cause a pins-and-needles feeling or numbness.

This effect on nerves may also temporarily make it harder for you to make precise motions right after a freezing dip. Five minutes after being immersed in cold water, most people cant put a key in a lock, Tedeschi says.

While you might be tempted to prepare for a polar bear plunge by extending your New Years Eve drinking into the wee hours, you should probably resist the urge. Your body will thank you.

Being drunk for anything temperature-related is bad, Tedeschi says.

In addition to impairing a person's judgment, alcohol is whats called a vasodilator it opens up your blood vessels (hence people get flushed after having a few). So, the effects of being drunk are going to interfere with your body's efforts to constrict your blood vessels after you plunge into icy water. And while the feeling of vasoconstriction might be a bit painful, its a natural effort your bodys making to try and preserve your vital organs, even in the midst of your decidedly non-sober judgment. All in all, a drunk polar bear plunger might stay in longer than is healthier for him or her, and will probably lose heat faster.

So, being drunk is probably not the best condition to attempt a polar bear plunge. Being hungover probably isnt as bad, but a person recovering from a night of drinking will likely be dehydrated and metabolically not at their best, Tedeschi says.

Continue reading here:
Polar Bear Plunge Physiology: What A Cold Water Dip On New Year's Day Does To Your Body


  1. Physiology