Adrenaline is a very important hormone and neurotransmitter that has functions in the brain and body. In some sources it is also referred to as epinephrine. Adrenaline is secreted from the adrenal glands in the body and some neurons in the brain around the brain stem. It is a very important hormone in stimulating the body. It enables the emergence of fight or flight behavior, acceleration of the heartbeat and high blood sugar. It prepares the necessary environment for the muscles to contract and consume energy.
It is produced naturally in the body and can be given as an external medicine. Maybe you have watched in the movies, in cases such as a heart attack, the patient is immediately given a big needle. Here is the adrenaline given to stimulate that heart. There is also a respirable adrenaline. This form of adrenaline can be administered when other treatment options do not work in patients with asthma. When given as a medicine, it can cause anxiety, tremors and sweating. Sometimes it can also lead to the occurrence of heart arrhythmias, such as tachycardia.
Duties in the Sympathetic Nervous System
90% of the adrenaline circulating in the body is produced in the adrenal glands. It has been observed that the adrenaline level is very low if these glands are removed. Adrenaline affects many muscles and neurons in the sympathetic nervous system. It performs its effects through alpha and beta receptors. Cells that respond to adrenaline are called adrenergic. You may have seen the expression of adrenergic neuron. But remember, most neurons in the sympathetic nervous system respond to noradrenaline, not adrenaline.
Let's reinforce what we have learned with an example about the adrenaline secretion's increasing. At 8 o'clock, you walk alone on the road at a time when the weather starts to darken. You noticed that a dog 100 meters ahead is running towards you. As soon as you notice, you can perceive the dog as a threat and start the adrenaline release. Your muscles contract to flight or fight. By increasing your blood sugar, your cells are fed more. The oxygen demand of the body is met by accelerating the heartbeat. Then as the dog approached you, he suddenly changed the road and the danger passed. Since the hormones are slow-acting molecules, your heartbeat doesn't return to normal immediately. This is because hormones such as adrenaline affect the intracellular signaling mechanism via G-coupled proteins. If it only affected ion channels, the effect would disappear much more quickly.
When is adrenaline secreted?
One of the factors that will trigger the adrenaline secretion in the body is exercise and sports. However, in order for the adrenaline to be secreted, the heartbeat needs to be accelerated a little. When your muscles begin to strain a bit, it activates hormones to make your body work easier. The blood flow in the liver is slightly reduced and the blood is directed to more needed areas. With the secretion of adrenaline, more glucose is given to the blood for muscle cells to use. The lung bronchi are expanding to facilitate breathing. Studies show that bronchial stenosis in asthma patients reverses with adrenaline administration.
The second factor that will increase the amount of adrenaline in the brain and body is stress and fear. Numerous experiments have been carried out on this subject. In one study, one group is given adrenaline, the other group is given nothing. After the injection, films are watched on both groups. Participants who received adrenaline in their body were found to have more negative facial expressions in movies than the control group. It was observed that the negative emotion felt as the amount of adrenaline increased. There is a clear link between adrenaline and fear.
Role in Memory
It has been observed that adrenaline plays a role in storing emotional stimulating events in horror films. Adrenergic hormones such as adrenaline improve long-term memory in humans. During the day, we take a lot of things into our brains and delete unnecessary ones in our sleep. Thanks to this information filter system of the brain, memory only records the important ones. How does he decide which events are important? At this point, hormones such as serotonin and adrenaline label events that stimulate us emotionally, information. This information is reinforced in our sleep and taken into long-term memory. In addition, adrenaline has roles in long-term stress compliance and emotional memory coding. It can activate arousal and fear memory in pathological conditions such as post-traumatic stress disorder.
Animal and human experiments so far have revealed that adrenaline has a powerful effect on memory. Giving the adrenaline to the participants during or after the learning process made it easier to code the information. The researchers found that ren adrenoceptors were involved in the coding of information. Since adrenaline does not have the ability to cross the blood brain barrier, it can show its effect partially through çevresel adrenoceptors in the peripheral nervous system.
How does adrenaline work?
After it is produced in the adrenal glands, adrenaline must mix with blood and go to target organs. This hormone, which has receptors in almost every organ, has different functions according to the type of tissue. For example, we mentioned that it is given to patients with asthma. It has the feature of relaxing the muscles around the respiratory tract. However, it provides contraction of the muscles around most of the small vessels, arterioles. Even if the hormone is the same, the receptors are different. Your key is the same but the doors are different. Each door leads to a different house.
Receptors play a big role in the working mechanism of adrenaline. We wrote that there are alpha and beta receptors. Binding of adrenaline to these receptors causes a series of metabolic events to begin. Binding to alpha receptors prevents the pancreas from secreting insulin. Instead, glycogenolysis begins. The stored glycogen is converted to glucose. The aim is to increase glucose and supply glucose to muscles and other cells. Binding to the beta adrenergic receptor initiates glucagon synthesis in the pancreas. On the other hand, it increases the release of adrenocorticotropic hormone (ACTH) in the pituitary gland in the brain. In the meantime, lipolysis also occurs in the fat tissue separation process. With the breakdown of glycogen into glucose and the decomposition of fats, the nutrients needed by the cells are provided and the amount of glucose and fatty acid in the blood is increased.
