Researchers uncover a shocking reason why the human brain is the most expensive organ to run. It constantly consumes 20% more energy to keep your body up and going. As it turns out, the brain's excessive energy consumption is due to a leak.
Understanding the Human Brain
According to Johns HopkinsMedicine, the brain is a complex organ that controls memory, thought, emotion, touch, vision, motor skills, breathing, and every other process that enables the body to prosper and work. The brain makes up for the central nervous system with the spinal cord.
An average adult will have a brain that weighs approximately 3 pounds and is composed of 60% fat. The other 40% combines salts, carbohydrates, proteins, and water. The brain itself isn't a muscle, contrary to popular belief, but contains nerves, blood vessels, neurons, and glial cells.
The most expensive organ of the body works by sending and receiving chemical and electrical signals throughout the human body. Different signals control different bodily processes, and the brain interprets each one. Some of these messages are kept within the brain, while some are relayed via the spine and across the body's networks of nerves and extremities. To do this, the body relies on billions of neurons.
Energy Leak: Why Does the Brain Use so Much Energy?
In a study published in the journal Science Advances, titled "Synaptic vesicle pools are a major hidden resting metabolic burden of nerve terminals," researchers found small sacs dubbed vesicles that hold messages being transmitted between cells in the brain that may constantly be oozing out energy. Researchers suspect that the leakages are a trade-off for the brain's ability to fire at all times without a moment's notice.
Timothy Ryan, senior author and a professor of biochemistry at Weill Cornell Medicine, New York City, explains that the brain is considered the most expensive organ to run. Previously, scientists have assumed that the energy suck is due to the brain's electric activity, which means that neurons or brain cells are constantly firing electrical signals to each other to communicate. The process is known to burn large amounts of energy molecules known as adenosine 5'-triphosphate (ATP)
However, over the past decades, clinical studies have shown that the brains of people in vegetative states or comas still consume massive energy amounts despite minimal electrical brain activity.
In recent years, Ryan and his team have analyzed junctions in the brain known as synapses, where neurons communicate and meet by launching tiny vesicles packed with chemical messengers known as neurotransmitters. The team previously showed that active synapses use a significant among of energy. However, in the new study, where researchers inactivated rat neuron synapses in Petri dishes using a toxin, the team realized that synapses alone consumed more energy than neurons firing.
They found that a proton pump was responsible for almost 44% of all energy used in resting synapses. Upon closer investigation, the team uncovers that the proton pump was forced to constantly keep working and burning ATP due to the vesicles "leaking" protons. Inactive synapses are prepared to launch the vesicles right away by pre-packing them with neurotransmitters. This is done with the help of yet another pump that sits on the vesicles' surfaces. This type of pump known as transporter proteins changes its shape to accommodate the neurotransmitters inside, and in exchange, it grabs protons from inside the vesicle, changes its shape once again, and spits out protons out of the vesicle.
For this intricate process to work, the vesicles must first have a high concentration of protons inside compared to their surroundings. However, researchers found that even when the vesicles were full, the transporter proteins continued to change shape despite not carrying neurotransmitters back into the vesicles.
Ryan explains that the team discovered the processes' inefficiencies. And although the leakages are small, it adds up to trillions that end up being a larger expense even without any electrical activity in the brain, reports LiveScience.
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