What happens inside the human body and the brain when it faints?

Perhaps you have even experienced the feeling of lightheadedness, the stomach can be sore, the sweaty palms, the vision closed, then, wake up on the floor, look at the ceiling and realize you have fainting. What happened?

Fainting can be caused by a number of factors. The last identified cause is not enough blood supply to the brain.

So far, the most common cause of syncope has been reduced blood pressure due to a strong vasovagal reaction . This reflex is named after the vagus nerve, which runs from the brain to the heart, lungs and gastrointestinal tract.

The work of vagus nerve is to regulate the human sympathetic nervous system. This is half of the autonomic nervous system. It all works without people having to think about it. Sympathetic functions are often considered characteristic of rest and digestion.

Syncope is a protective mechanism of the human body.

For example, in the heart, the vagus nerve releases a neurotransmitter called acetylcholine . Acetylcholine binds to special pacemaker cells to slow heart rate. Behaviors such as deep, slow breathing during yoga try to increase sympathetic activity, slow the heart and lead to a more relaxed state.

Although relaxation is a good thing, too much slowing of heart activity is not recommended because when it leads to a brief loss of consciousness. You need your heart rate to be a certain number of beats per minute to fully contribute to overall blood pressure.

The other half of the autonomic nervous system is a combat reaction, a function that is opposite to the sympathetic nervous system.

It ensures that small blood vessels in the body's tissue maintain a basic contraction level. This resistance when blood flows through all narrow blood vessels contributes to a sufficient blood pressure for the entire system.

The increase in activity reverses this resistance, allowing blood to stay in peripheral tissues instead of towards the heart and brain. Lack of resistance, along with reduced heart rate, causes blood pressure to drop significantly.

However, think of a person who fainted when he saw blood. What is happening there can lead to this overactive vasovagal reaction?

Usually, when the body feels initial stress like seeing blood, it activates a fearful reaction that increases the activity of the sympathetic nervous system and increases heart rate. The reflex body compensates by increasing sympathetic activity to slow the heart rate back to normal. But if the sympathetic system compensates too much and reduces the heart rate too much, blood pressure can drop too much, the brain will lack oxygen and you lose consciousness.

Although the cause of fainting, loss of consciousness is often brief, most people will come immediately after touching the floor or even slipping in a chair. In this sense, some researchers have suggested that syncope is a protective mechanism of the human body.