Heart has its own 'mini-brain' that controls its beat

Every beat of your heart is not a random act, but the result of complex interplay between your brain and heart. But did you know there is a smaller brain – a mini nervous system tucked away in the heart that commands each pulsation?

It’s a fascinating world within our body that scientists from Karolinska Institutet and Columbia University have started decoding.

Their research shows that the heart has a “mini-brain.” This means the heart has its own nervous system that controls its heartbeat. Moreover, scientists say this system is much more complex than previously thought.

Mini-brain of the heart

Until now, people thought the heart was controlled solely by the autonomic nervous system. This system sends signals from the brain to control different functions.

The heart’s own neural network was seen as a simple structure and was believed to just relay brain signals. However, new research shows that the heart’s nervous system plays a much more advanced role.

The heart’s complex nervous system

“This ‘little brain’ has a key role in maintaining and controlling the heartbeat, similar to how the brain regulates rhythmic functions such as locomotion and breathing,” explains Konstantinos Ampatzis, the principal researcher at Karolinska Institutet and leader of this research.

In the study, researchers discovered several types of neurons in the heart, each serving a unique purpose.

One of these groups of neurons has pacemaker properties, meaning it helps regulate the heart’s rhythm.

This discovery of the mini-brain challenges the existing understanding of how the heart beats, and suggests that the heart’s nervous system is much more complex than previously believed.

The finding could have significant implications for how we treat heart conditions in the future, especially those related to rhythm, like arrhythmias.

Studying the heart’s mini-brain

The researchers used zebrafish for their study. Zebrafish hearts are similar to human hearts in several ways, including heart rate and general function. This similarity makes zebrafish a good model for understanding the human heart.

“We were surprised to see how complex the nervous system within the heart is,” said Ampatzis. He noted that understanding this system could lead to new insights into heart diseases. It might even help develop new treatments for conditions like arrhythmias.

To explore the heart’s neural network, the researchers used several advanced techniques. These included single-cell RNA sequencing, anatomical studies, and electrophysiological methods.

These tools helped them understand the composition, organization, and function of the heart’s neurons.

New possibilities for treatment

The next step for the researchers is to understand how the heart’s mini-brain interacts with the actual brain. They aim to see how these systems work together under different conditions, such as exercise, stress, or disease.

“We will now continue to investigate how the heart’s brain interacts with the actual brain to regulate heart functions under different conditions such as exercise, stress, or disease,” said Ampatzis.

The experts hope to identify new therapeutic targets by studying disruptions in the heart’s neural network.

The study was a collaboration with researchers from Columbia University in the U.S.A. It received funding from organizations like the Dr. Margaretha Nilsson Foundation, Erik and Edith Fernström Foundation, StratNeuro, and Karolinska Institutet.

The heart: An incredibly efficient organ

The heart’s primary function is to pump blood throughout the body, thus delivering oxygen and nutrients while removing waste products.

The organ is incredibly efficient. It beats about 100,000 times a day, pumping around 2,3 fluid ounces (70 milliliters) of blood with each beat. This adds up to nearly 158 pints (75 liters) of blood every minute!

Despite its size, the heart is strong enough to pump blood throughout the entire body, reaching every cell, tissue, and organ.

The heart works harder when you stand up. Gravity causes blood to pool in the lower parts of your body, so the heart has to pump more forcefully to keep the blood flowing upward.

Interestingly, it only takes about 30 seconds for blood to travel from your heart to your toes and back again.

The heart can keep beating outside the body under the right conditions, which makes heart transplants possible. It can also adapt to physical activities. For example, an athlete’s heart can grow larger and pump blood more efficiently over time.

A better understanding of the interaction between the heart and brain could improve treatments for mental health conditions that are associated with heart problems.

The study is published in the journal Nature Communications.

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