Understanding the evolution of lungs through physical principles

How fluid dynamics and transport shaped the structure of our lungs in the course of evolution

2013-10-04

(Press-News.org) Two French physicists, Bernard Sapoval and Marcel Filoche from École Polytechnique in Palaiseau, France, suggest in a study published in EPJ E how evolution has shaped our lungs through successive optimisations of physical parameters such as conservation of energy and speed of delivery.

Our respiratory system consists of a bronchial tree designed to transport air through the lungs combined with an alveolar system designed to capture the oxygen. Both are subjected to different type of optimisations. Only tree-like structures, the paper shows, are able to efficiently feed organs above a small size, below which organs are solely fed by diffusion. Specifically, the authors first show that energy losses of fluids during transport are minimised in a tree-like structure of fractal dimension 3. Second, they indicate that this optimised tree is also 'space-filling' to optimise proximity to the working alveolae. Third, they show that a system designed to reduce the time spent to transport fluids throughout an organ has the same fractal optimisation.

In an evolutionary perspective, the size of primitive multi-cellular species was necessarily limited by nutrients' diffusion speed. One hypothesis defended in this study is that larger primitive animals have thus been conditioned by a progressive Darwinian selection of tree-like 'space-filling' nutrient distribution systems. Then, their genetic material was ready to be shared to allow mammalian respiration. Successive inspirations and expirations cycles had to be optimised so that external air could reach the alveoli before expiration starts. This form of evolutionary tinkering, the authors believe, would have allowed the emergence of mammalian respiration—as opposed to fish-style breathing through gills.

Similarly, the paper shows that the structure of the alveolar system is indeed optimal to allow efficient transport of oxygen from the air to the blood. This new insight into the lung's evolutionary process stems from the physical principles underlying the architecture of living systems.

### References: B. Sapoval and M. Filoche (2013), Optimisations and evolution of mammalian respiratory systems, European Physical Journal E, DOI 10.1140/epje/i2013-13105-1

For more information visit: http://www.epj.org

The full-text article is available to journalists on request.

ELSE PRESS RELEASES FROM THIS DATE:

International research collaboration reveals the mechanism of the sodium-potassium pump

2013-10-04

It's not visible to the naked eye and you can't feel it, but up to 40 per cent of your body's energy goes into supplying the microscopic sodium-potassium pump with the energy it needs. The pump is constantly doing its job in every cell of all animals and humans. It works much like a small battery which, among other things, maintains the sodium balance which is crucial to keep muscles and nerves working. The sodium-potassium pump transports sodium out and potassium into the cell in a fixed cycle. During this process the structure of the pump changes. It is well-established ...

Surprisingly simple scheme for self-assembling robots

2013-10-04

CAMBRIDGE, MA -- In 2011, when an MIT senior named John Romanishin proposed a new design for modular robots to his robotics professor, Daniela Rus, she said, "That can't be done." Two years later, Rus showed her colleague Hod Lipson, a robotics researcher at Cornell University, a video of prototype robots, based on Romanishin's design, in action. "That can't be done," Lipson said. In November, Romanishin — now a research scientist in MIT's Computer Science and Artificial Intelligence Laboratory (CSAIL) — Rus, and postdoc Kyle Gilpin will establish once and for all that ...

Dartmouth researcher finds a new role for the benefits of oxygen

2013-10-04

Hanover, N.H.—In a study published in published in EMBO Molecular Medicine, a Dartmouth researcher found that dying heart cells are kept alive with spikes of oxygen. During a heart attack when the flow of oxygen-rich blood to a section of the heart is interrupted, and not quickly restored, heart muscle begins dying. Deprived of oxygen and other essential nutrients, cell death continues occurring over a period of time leading to progressive loss of heart function and congestive heart failure. Current therapies are not effective at limiting cell loss—they only slow down ...

Well-connected hemispheres of Einstein's brain may have sparked his brilliance

2013-10-04

TALLAHASSEE, Fla. - The left and right hemispheres of Albert Einstein's brain were unusually well connected to each other and may have contributed to his brilliance, according to a new study conducted in part by Florida State University evolutionary anthropologist Dean Falk. "This study, more than any other to date, really gets at the 'inside' of Einstein's brain," Falk said. "It provides new information that helps make sense of what is known about the surface of Einstein's brain." The study, "The Corpus Callosum of Albert Einstein's Brain: Another Clue to His High ...

Stem cells engineered to become targeted drug factories

2013-10-04

A group of Brigham and Women's Hospital, and Harvard Stem Cell Institute researchers and collaborators at MIT and MGH have found a way to use stem cells as drug delivery vehicles. The researchers inserted modified strands of messenger RNA into connective tissue stem cells—called mesenchymal stem cells—which stimulated the cells to produce adhesive surface proteins and secrete interleukin-10, an anti-inflammatory molecule. When injected into the bloodstream of a mouse, these modified human stem cells were able to target and stick to sites of inflammation and release biological ...

Ultraviolet light to the extreme

2013-10-04

WASHINGTON, D.C. Oct. 4, 2013 -- When you heat a tiny droplet of liquid tin with a laser, plasma forms on the surface of the droplet and produces extreme ultraviolet (EUV) light, which has a higher frequency and greater energy than normal ultraviolet. Now, for the first time, researchers have mapped this EUV emission and developed a theoretical model that explains how the emission depends on the three-dimensional shape of the plasma. In doing so, they found a previously untapped source of EUV light, which could be useful for various applications including semiconductor ...

NSF awards $12 million to SDSC to deploy 'Comet' supercomputer

2013-10-04

The San Diego Supercomputer Center (SDSC) at the University of California, San Diego, has been awarded a $12-million grant from the National Science Foundation (NSF) to deploy Comet, a new petascale supercomputer designed to transform advanced scientific computing by expanding access and capacity among traditional as well as non-traditional research domains. Comet will be capable of an overall peak performance of nearly two petaflops, or two quadrillion operations per second. "Supercomputers such as Comet and our data-intensive Gordon system are helping to fulfill the ...

New kind of microscope uses neutrons

2013-10-04

CAMBRIDGE, MA -- Researchers at MIT, working with partners at NASA, have developed a new concept for a microscope that would use neutrons — subatomic particles with no electrical charge — instead of beams of light or electrons to create high-resolution images. Among other features, neutron-based instruments have the ability to probe inside metal objects — such as fuel cells, batteries, and engines, even when in use — to learn details of their internal structure. Neutron instruments are also uniquely sensitive to magnetic properties and to lighter elements that are important ...

Reading literary fiction improves 'mind-reading' skills

2013-10-04

NEW YORK (October 3, 2013)—Heated debates about the quantifiable value of arts and literature are a common feature of American social discourse. Now, two researchers from The New School for Social Research have published a paper in Science demonstrating that reading literary fiction enhances a set of skills and thought processes fundamental to complex social relationships—and functional societies. Ph.D. candidate David Comer Kidd and his advisor, professor of psychology Emanuele Castano performed five experiments to measure the effect of reading literary fiction on participants' ...

Analysis of little-explored regions of genome reveals dozens of potential cancer triggers

2013-10-04

A massive data analysis of natural genetic variants in humans and variants in cancer tumors has implicated dozens of mutations in the development of breast and prostate cancer, a Yale-led team has found. The newly discovered mutations are in regions of DNA that do not code for proteins but instead influence activity of other genes. These areas represent an unexplored world that will allow researchers and doctors to gain new insight into the causes and treatment of cancer, said the scientists. "This allows us to take a systematic approach to cancer genomics," said Mark ...

Understanding the evolution of lungs through physical principles

ELSE PRESS RELEASES FROM THIS DATE:

LAST 30 PRESS RELEASES: