The Physiology of Stress

Overview

The endocrine system of the human body comprises the glands that help in maintaining the homeostasis. Further, each gland in this system release and produce hormones that enter the body through the bloodstream to specific organs. Thus, in order to live a full life, it is important for this system to function properly. The hormones in the endocrine systems "acts" as the chemicals that control the body system ( Spencer et al. 2015). To be specific, they control growth, metabolism, sexual function, development, and reproduction. Some of the glands in the endocrine system include the Hypothalamus, Pituitary, Thyroid, and Parathyroid glands. For the purposes of this study, I will focus on the pituitary endocrine gland.

The Pituitary Gland

In the endocrine system, the pituitary gland is the central organ that controls most of the most of the basic physiological functions such as reproduction, growth, and metabolic hemostasis. It is located under the optic chiasm at the base of the brain, inside a depression between the sella turcica and the upper surface of the sphenoid bone. Most importantly, this gland consists of two major parts which are the neurohypophysis and the adenohypophysis. The two parts are involved in either hormone secretion or hormone production. Also, it is also referred as the “Master Gland” due to its ability to direct other organs and endocrine glands to either induce or suppress hormone production.

Pituitary Hormones: In this gland, the hormone is produced by the posterior or anterior lobes which aid in different functions of the body. The anterior lobes secret the anterior hormones while posterior lobe secrets the vasopressin and oxytocin which are known as an antidiuretic hormone. The latter hormones functions in maintaining and stabilize the level of water in the body regardless of the water intake. In simple terms, its role is the secretion of the dilute urine. With this, it helps in conserving the body’s water to ensure that much of it is not lost. Normally, these hormones function in the organs such as the vascular system and the kidney where most of the water loss and intake take place ( Allain et al. 2018). On the other hand, the anterior hormones include the adrenocorticotropic and endorphins that function in the nervous system to reduce pain sensitivity. It works with other hormones such as luteinizing hormone (LH), follicle stimulating hormone (FSH) and antidiuretic hormone (ADH) in order to make the functions of the body complete. LH I females stimulates the final maturation of the ovulation. The Graafian follicle, and the development of the corpora lutea. In the males, it helps in the testosterone production stimulation by the testis. Other than maintaining spermatogenesis, the facilitate the development of the accessory sex organs such as the prostate, vas deferens, and seminal vesicles.

Pituitary Implication and Response to Stress: Pituitary gland is the central point for “stress circuit” in the body system. The human body system is able to respond to either perceived or real threat through the interplay between the nervous system and hormones. In short-term, the response of these hormones helps the body to deal with any immediate threat. As a result, the hormonal systems shut down from undertaking any function. The body is said to be in an inner calm or balance (steady state) while in absence of stress. Thus, stress is a threat to the steady state or homeostasis of the body and it creates an imbalance of the body hormones. Restoration of homeostasis in the body system requires an adaptive response either physical or behavioral. Chronic or unremitting stress conditions may have negative health consequences but responding in and of itself is healthy. The stress circuit in the body helps in dealing with serious physical threats. When the body is under acute stress, the hypothalamus, a brain region releases corticotropin-releasing hormone (CRH) which responses through the pituitary gland. An example of an acute stress is where you tell your boss that you haven’t done with the task and he or she gives you an extra time. The additional time reduces the threat over the stress response system. A signal is sent to all the brain levels telling it to calm and switch off the Hypothalamic-Pituitary-Adrenal (HPA) axis. As a result, the pituitary glands stop production of adrenaline and cortisol hormones. Some physical observation may include heart rate returning to normal, temperature cools down, and also, stomach start digesting your food again (Atmaca et al. 2017) . An example of chronic stress is said you getting a reminder every day that you are suffering from an incurable disease and living days reducing that you constantly feel stressed. The HPA axis responds by telling the body to suppress functions such as eating appetite and increase blood pressure. Chronic stress is harmful to your health!

Stress-related Disorder

Pituitary Tumors: One of the most common stress-related disorder is pituitary tumors or pituitary adenomas. The HPA axis response to a short burst of stress by stimulating the hormonal overproduction in the pituitary glands and thus, causing endocrine disturbances. In the short-term, as these tumors enlarge, they compress the normal pituitary and thus, resulting to absent or decreased hormone production, visual loss from optic chiasm and a constant headache. In the long-term, the pituitary disorder results in internal bleeding and into an intracranial surgery.

Treatment: First, the treatment of pituitary tumors depends on whether or not there is excessive production of hormones. Some of the treatments include surgery, radiation, and medicines to treat pituitary tumors. However, the combination of more than one treatment is used. For example, a tumor can be removed using a surgery while medicines can be used to shrink the remaining part of the tumor and relieve symptoms.

References

Allain, E. P., Venzl, K., Caron, P., Turcotte, V., Simonyan, D., Gruber, M., ... & Vanura, K. (2018). Sex-dependent association of circulating sex steroids, pituitary hormones and treatment-free survival in patients with chronic lymphocytic leukemia.

Atmaca, M., Ozer, O., Korkmaz, S., Taskent, I., & Yildirim, H. (2017). Evidence for the changes in pituitary volumes in patients with post-traumatic stress disorder. Psychiatry Research: Neuroimaging ,  260 , 49-52.

Spencer, S. J., Emmerzaal, T. L., Kozicz, T., & Andrews, Z. B. (2015). Ghrelin’s role in the hypothalamic-pituitary-adrenal axis stress response: implications for mood disorders.  Biological Psychiatry ,  78 (1), 19-27.