Acute stress response on circulatory system.
When the body experiences stress, the hypothalamus in the brain sends a signal to the pituitary gland to release a hormone called ACTH. ACTH then signals the adrenal glands to release stress hormones such as adrenaline and cortisol. These hormones then travel through the bloodstream and reach the heart, causing an increase in heart rate and blood pressure. This increased heart rate and blood pressure allows more blood to flow to the muscles, providing them with the oxygen and energy needed to respond to the perceived threat.
Adrenaline also causes the blood vessels in the skin and internal organs to constrict, redirecting blood flow to the muscles. This process, called vasoconstriction, increases blood pressure and helps to ensure that the muscles have enough oxygen to respond to the perceived threat.
Cortisol also plays a role in the stress response by increasing the amount of glucose, or sugar, in the bloodstream, providing the body with an additional source of energy.
While these changes in the circulatory system can be beneficial in the short term, allowing the body to respond quickly to a perceived threat, prolonged or chronic stress can have negative effects on the circulatory system, increasing the risk of heart disease, stroke, and other health problems.
Additionally, during the alarm stage, the sympathetic nervous system (SNS) is activated, which causes the release of catecholamines like adrenaline and noradrenaline. These hormones increase heart rate and blood pressure, and cause blood vessels to constrict in non-essential areas such as the skin and gut, and dilate in essential areas such as muscles and brain. This helps to ensure that the body has enough oxygen and energy to respond to the perceived threat.
The increased blood flow to the muscles also causes a release of glucose from the liver, providing an additional source of energy for the muscles. This is known as the glycogenolysis.
It's also worth mentioning that, along with the physiological changes that occur during the alarm stage of the stress response, there are also psychological changes that occur. The person may feel anxious or panicked, and their attention and focus may become more heightened.
The alarm stage of the stress response is a normal and adaptive response in the short term, but if it persists for prolonged periods of time, it can lead to chronic stress, which can have negative effects on the body and mind. Chronic stress can lead to a variety of health problems, such as cardiovascular disease, diabetes, depression and anxiety.
One other important aspect to consider is that, during the alarm stage of stress response, the body also activates the coagulation system and the inflammatory response. This is done in order to prepare the body for potential injuries and bleeding that could occur during a physical fight or flight response. Platelets and clotting factors are activated which lead to the formation of a clot or thrombus, this could be problematic if the thrombus forms in a blood vessel that supplies the heart or brain, leading to a heart attack or stroke.
The inflammatory response is activated by the release of pro-inflammatory cytokines, which could increase the risk of chronic diseases like autoimmune disorders, cancer, and chronic obstructive pulmonary disease (COPD) if it persists for prolonged periods of time.
In summary, during the alarm stage of the stress response, the body activates a complex physiological response to prepare for a perceived threat. The body releases stress hormones and activates the SNS, which cause an increase in heart rate, blood pressure, and blood flow to the muscles, as well as activating the coagulation and inflammatory response. While this response is adaptive in the short term, chronic stress can have negative effects on the body and mind, leading to a variety of health problems.