UPR.E | Under Pressure…No Stress! |

UPR.E | Under Pressure…No Stress!

You think your upcoming exams cause pressure? Try having 100 feet of water above you trying to squish your body into a much smaller package.

We talked about the effects of air pressure on the human body–how your lungs work in regards to that pressure and why your ears pop on a commercial airliner. So what about when you go underwater? I mean, it’s not the like the Hab flies, so why are we worried about this?

We know that as you rise in altitude, the air pressure decreases, and vice versa as you descend into the airport, and that commercial airplanes are really just pressure vessels with wings and engines. The Aquarius, what we like to call the Hab, is also a pressure vessel, but instead of maintaining the pressure you have from the atmosphere, we have to contend with the pressure of water pushing down around us.

Under Pressure

What exactly is pressure? Well, in general we define pressure as the force, per unit area–pounds per square inch, per square foot or metre, for instance–applied to the surface of something like an airplane skin or the hull of the Hab.

Water is heavy, and the more of it that there is, the heavier it gets. If you’ve ever carried a gallon of milk home from the store, you’ll know that it’s not exactly light. That gallon of milk, which is mostly water, weighs about eight pounds. When you dive, the weight of water increases by fifteen pounds per square inch for every thirty-three feet you descend. After you dive only a couple of feet of water the weight of the water around you and above you is already becoming too much for your lungs to expand or contract, which is why you can’t just use a really long snorkel. You need the positive pressure provided by a compressed gas tank.

Try saying that ten times fast: Positive pressure provided, positive pressure provided, positive…okay, never mind.

Okay, so if at thirty-three feet your lungs are already in trouble, what do you think happens at one hundred feet? Well first things first, you’re now feeling four times the amount of pressure that you’d feel on the surface, which would, as you can imagine, cause the spongy tissue in your lungs to contract, leaving you with very little workable material in there to expand and contract.

Dive Response

A couple of other interesting things happen, and they’re commonly termed “dive response”. One of the first things that happens is that your body responds to the added pressure by constricting blood flow to your limbs so that the heart and brain can have priority – the body sort of figures it can live without limbs, but it can’t live without a brain and the brain needs the heart pushing as much of the oxygenated blood it can get. Funny how the brain gets to make these decisions – wonder what your arms and legs would think of this…

Anyway, with the extra blood expanding the vessels in the chest, this helps the body balance pressure with the outside environment.

Another interesting thing that happens is that on the deepest dives, your heart rate can dip as far only 14 beats per minute – that’s actually lower than a person in a coma. In fact, it’s about a third the heart rate of a person in a coma. We’re not quite sure how it works, but somehow your body’s self-preservation manages to keep you conscious even though your heart is barely beating.

Pressure is a tremendous force on our body, whether it’s very low or very high. But what if the pressure is really high, from being really far underwater?

Curriculum Reference Links

Physical World / Systems and Interactions / 3: Students should be able to investigate patterns and relationships between physical observables
Biological World / Systems and Interactions / 4: Students should be able to describe the structure, function, and interactions of the organs of the human digestive, circulatory and respiratory systems

10 Fun Facts: The Hab

1. Aquarius is the the world’s only permanent undersea research station.

2. Most missions last about two or three weeks.

3. Fabien Cousteau, grandson of Jacques Cousteau, beat his grandfather’s record month-long underwater expedition by spending 31 days on the Aquarius Reef Base in 2014.

4. The lab is used by NASA, the US Navy, and researchers and educators from around the globe for training and research.

5. The internet connection is better in the Hab than at many places above the water.

6. You have to swim underneath the facility in order to enter it.

7. Crew members are called aquanauts (NOT aquaNUTS!)

8. In 1994, a crew of scientists and divers had to evacuate Aquarius and climb up a rescue line to the surface in 15-foot seas after one of the habitat’s generators caught fire.

9. Aquarius was featured in the comic strip Sherman’s Lagoon in 2012.

10. The Hab was originally built in Texas.

10 Fun Facts: Coral

1. Reefs usually grow up on the east shore of land masses.

2. Parts of a coral reef can be harvested to make medications to treat cancers and other illnesses.

3. A coral reef isn’t a single organism; it’s actually a community of life that lives and thrives in one location.

4. Only about one percent of the world’s oceans contain coral reefs. That’s about the size of France.

5. Coral reefs are the largest biological structures on earth.

6. Corals are related to jellyfish and anemones.

7. There are over 2,500 species of corals. About 1,000 are the hard corals that build coral reefs.

8. Reefs grow where there are stronger wave patterns and currents to deliver food and nutrients.

9. The Great Barrier Reef is 500,000 years old.

10. Most coral reefs grow just about two centimeters per year.

10. Most coral reefs grow just about two centimeters per year.

10 Fun Facts: Invasive Species

1. To be considered invasive, a species must adapt to a new area easily. It must reproduce quickly. It must harm property, the economy, or the native plants and animals of the region.

2. Some invasive species are introduced accidentally, but others are brought deliberately.

3. Ship ballast water transports between 3,000 and 7,000 foreign species daily around the globe.

4. The total loss to the world economy as a result of invasive non-native species has been estimated at 5% of annual production

5. Invasive species have contributed to 40% of the animal extinctions that have occurred in the last 400 years.

6. Rodents are some of the worst invasive species.

7. There are an estimated 50,000 wild ring-necked parakeets in parks across London and southeast England.

8. Black and Norway rats annually consume stored grains and destroy other property valued over $19 billion.

9. Northern Pacific seastars reproduce very quickly. In one area where they were introduced, their population reached an estimated 12 million seastars in just two years.

10. Starlings were introduced to New York in the late 1800s, as part of an attempt to bring animals that were mentioned in Shakespeare‘s work to America.

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