Why Do People Faint?

Fainting is the temporary loss of consciousness technically termed as syncope. Losing consciousness is not uncommon to us. We see and hear about a lot of people getting soft in the knees and then gradually becoming unconscious while in the middle of something. But why do people faint? What triggers syncope in people? There are people who seem to faint for no reason at all. However, most people faint when hearing distressing news, or when something grave happens. There are others who faint when feeling immense pain, seeing their nightmare or when having panic or anxiety attacks. A familiar situation happens when people see blood; it occurs during accidents, medical operations or in bloodlettings. Then again, why do people faint for no reason? Why do people faint at the sight of blood or why do people faint when donating blood?

Scientists and researchers have identified fainting as the result of insufficient blood flow and oxygen supply to the brain caused by many different conditions such as those mentioned above. How exactly do these situations minimize the blood flow to the brain? For one, some of these instances are grounds for heart rhythm changes. Panic and anxiety attacks, including encounters with something that one fears, may cause a rapid heart rate, also known as tachycardia (tachy meaning fast and cardiac pertaining to  heart). It is an abnormal heart rhythm with either the upper or lower chambers of the heart responsible for its production. The quick beating of the heart decreases the time for blood to fill it, and as a result, there is less blood available for distribution throughout the body particularly the brain. In effect, the person having tachycardia will then have a syncopal period.

Another change in heart rhythm happens the other way around. Bradycardia (brady meaning slow) is the measured beating of the heart, limiting its function to pump blood, which is a common consequence of old age. With the decreased ability of the heart, less blood and oxygen will be able to reach the brain. A decrease in heart rate and amount of blood pumped may also arise to what is known as vasovagal syncope. Vasovagal syncope occurs when there is a drop in the blood pressure due to the chemical imbalance between adrenaline and acetylcholine. While adrenaline is responsible for the rush of blood, acetylcholine is in charge of the opposite. When there is an excess of this chemical, the blood vessels loosen up and dilate, and the heart rate slows. This becomes a greater challenge for the blood to be pumped to the brain. This reduced circulation to the brain usually precedes syncope.

These are the two main responses that a person who sees or donates blood naturally comes up with. For other people who seem to have no reason at all for fainting may have other physical or psychological deficiencies. Whatever these may be, they are all responsible for the decreased flow of blood to the brain that revolves around the heart’s inability to pump blood, the incapacity of blood vessels to channel the blood or simply the lack of blood. Ironic though that for others, it is still blood that triggers the lack of its flow in our brain.

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