Interaction between Cortisol and the Limbic System
The limbic system plays an essential role in the regulation of emotional health. The system comprises of hypothalamus, hippocampus, and amygdala that assist in managing and controlling hormonal, emotional, and visceral responses within and outside our bodies. Stress is associated with neuroendocrine, neuroanatomical, and neurotransmitter disorder. However, the interconnection between neuropeptide and neurotransmitter circuit in the brain stem, limbic, and cortical area make it difficult to differentiate the functions of the two. Several systems regulate the stimuli responsible for the body’s alteration. For instance, two systems accountable for anxiety and mood changes are the hypothalamic-pituitary-adrenaline (HPA) axis and the autonomic nervous system. The sympathoadrenal medullary (SAM), in conjunction with the sympathetic and parasympathetic nervous system, would initiate a response to any psychological disorder for stress adaptation and revert the body to its routine homeostasis nature.
When the body senses a life-threatening situation, it generates a “fight-or-flight” response, which acts as a defense system. The reactions commence in mind where, after sensing something unusual, the eye may send a signal to the amygdala, which processes it and, upon perceiving danger, relay distress to the hypothalamus. The prefrontal cortex assists the amygdala in processing the information as it controls our thoughts hence regulating our emotional responses. The hypothalamus then communicates with other body parts via the autonomic nervous system that triggers the fight-or-flight response while also monitoring the control mechanisms. After the amygdala relays the distress information, the hypothalamus stimulates the sympathetic nervous system by signaling the adrenal gland via autonomic nerves to release adrenaline hormone into the bloodstream. As the hormone circulates through the body, it brings some physiological effects while also releasing glucose, which ensures an adequate supply of energy.
With the diminishing surge of adrenaline, the hypothalamus stimulates the HPA axis that connects the pituitary glands, hypothalamus, and adrenaline glands. HPA axis depends on the hormonal responses. Upon perception of danger, the hypothalamus secretes corticotropin-releasing hormone (CRH), which sails to the pituitary gland to stimulate the discharge of adrenocorticotropic hormone (ACTH). The process continues with ACTH traveling to adrenaline glands, triggering cortisol release. Cortisol maintains the body fight and flight response, keeping it on high alert to any dangerous situation. A rise in cortisol level, as a result, increases the heartbeats, shoving blood to the heart, muscles, and other critical parts of the body. It also increases the BP and pulse rate. It can further stimulate faster breathing, allowing a wide opening of the small airways in the lungs. Such boosts the volume of oxygen the lungs take per to breathe, thus increasing the amount of oxygen reaching the brain, which ultimately increases alertness. The senses of the body also become sharper.
Upon the departure of the danger, which is regarded as a short-term condition, cortisol levels decrease as the parasympathetic nervous system sets in to regulate the stress response hormones. It put a brake to the fight-or-flight response and returns the body to its normal homeostatic process. Short-term stress releases a large volume of cortisol. However, if there is continuous activation of HPA, for example, experiencing stress for a longer duration, the stress-response system will adjust in an attempt to deal with the situation. The system will secrete less cortisol because a lot is still present in the body. The condition thus results in an imbalance of cortisol and ineffective performance of the stress-response system.