Endocrine System
Charles Paul Lambert in Physiology and Nutrition for Amateur Wrestling, 2020
The adrenal gland has two important areas from which it secretes hormones. One is the adrenal medulla and the other is the adrenal cortex. Both the adrenal medulla and the adrenal cortex are involved in the “fight or flight” response. The adrenal medulla secretes epinephrine (adrenaline) and norepinephrine (noradrenaline) while the adrenal cortex secretes the glucocorticoid cortisol and the mineralocorticoids, primarily aldosterone. Epinephrine has a myriad of effects, like stimulating the breakdown of glycogen in muscle and liver cells, increasing the strength of contraction of the heart, and liberating fatty acids and glycerol from triglycerides at the adipocyte. Also, epinephrine acts to cause dilation of the precapillary sphincters of the arterioles in skeletal muscle capillary beds allowing for increased perfusion, i.e., blood flow to skeletal muscle during exercise. Norepinephrine generally increases heart rate and causes vasoconstriction all over the body. As opposed to the hormonal control of the release of epinephrine and norepinephrine from the adrenal medulla it is under direct sympathetic nervous system control. That is, when “fight or flight” situation arises, the nervous system stimulates the release of epinephrine and norepinephrine from the adrenal medulla.
The adrenal glands and other abdominal endocrine disorders
Professor Sir Norman Williams, Professor P. Ronan O’Connell, Professor Andrew W. McCaskie in Bailey & Love's Short Practice of Surgery, 2018
The weight of a normal adrenal gland is approximately 4 g. There are two distinct components to the gland: the inner adrenal medulla and the outer adrenal cortex (Figure52.1). The adrenal glands are situated near the upper poles of the kidneys, in the retroperitoneum, within Gerota’s capsule. The right adrenal gland is located between the right liver lobe and the diaphragm, close to and partly behind the inferior vena cava (IVC). The left adrenal gland lies close to the upper pole of the left kidney and the renal pedicle. It is covered by the pancreatic tail and the spleen (Figure52.2). The adrenal glands are well supplied by blood vessels. The arterial blood supply branches from the aorta and the diaphragmatic and renal arteries and varies considerably. A usually single large adrenal vein drains on the right side into the vena cava and on the left side into the renal vein.
A Biopsychosocial Approach to Anxiety
Stephen M. Stahl, Bret A. Moore in Anxiety Disorders: A Guide for Integrating Psychopharmacology and Psychotherapy, 2013
Cortisol is a glucocorticoid, a class of steroid hormone, released from the zona fasciculata of the adrenal gland in response to stressful stimuli (Radley et al., 2011). The release of cortisol is controlled by the HPA axis. As already described, CRH secretion by the hypothalamus triggers the release of ACTH from the pituitary gland, which subsequently travels through the blood to the adrenal gland, resulting in glucocorticoid secretion. Cortisol has a multitude of functions in the body, including suppression of the immune response, increasing blood glucose levels, and aiding metabolism. Of greater interest in recent years is cortisol's role in an adaptive response to stress. Cortisol is secreted during the body's “fight or flight” response to danger or threat (Korte, Koolhaas, Wingfield, & McEwen, 2005). The transient release of cortisol during a response to stressful or fearful stimuli results in several advantageous changes to aid in survival, substantiated by several lines of clinical evidence, such as increased energy, resourceful emotional memory encoding, hypervigilance, and heightened attention (Munck, Guyre, & Holbrook, 1984). While the release of cortisol to mediate an adaptive response to danger is beneficial in the short term, high levels of cortisol in the long term can have harmful physical and psychological effects.
Management of adreno-cortical adenomas using microwave ablation: study of the effects of the fat tissue
Published in International Journal of Hyperthermia, 2022
Anna Bottiglieri, Martin O’Halloran, Giuseppe Ruvio, Laura Farina
Figure 2 shows a three-dimensional (3 D) model representing a pyramidal-shaped adrenal gland and the position of the gland on the top of the kidney. First, a pyramidal shell is designed within a three dimensional (3 D) full-wave electromagnetic software (CST MWS Suite 2018, Darmstadt, Germany). The shell is scaled to reproduce the dimensions of the medulla (inner shell) and the cortex (outer shell) [35]. The geometries representing the medulla and cortex are 13 mm and 24 mm in height, 40 mm and 60 mm in width, 20 mm and 30 mm in thickness. A fat capsule envelope the modeled adrenal tissues. The dimensions of the fat capsule are 45 mm in height, 108 mm in width and 30 mm in thickness. Finally, the model of the adrenal gland is arranged on top of a kidney model (49 mm in height, 32 mm in width and 33 mm in thickness) in agreement with [31]. Table 1 lists dielectric and thermal properties assigned to each tissue of the model. For the cortex and medulla, the dielectric properties at the operating frequency of 2.45 GHz reported in [30] are loaded into the material library of the CST MW Studio software. The dielectric properties of fat and kidney as well as the values related to the specific heat capacity, thermal conductivity and density of each material are acquired from the literature [36] and manually loaded into the material settings of the simulation software.
The controlling role of nitric oxide within the shell of nucleus accumbens in the stress-induced metabolic disturbance
Published in Archives of Physiology and Biochemistry, 2021
Yasaman Husseini, Alireza Mohammadi, Gila Pirzad Jahromi, Gholamhossein Meftahi, Hedayat Sahraei, Boshra Hatef
The adrenal gland has two parts, medulla and core. The HPA axis terminates to the core, and sympathetic nerves stimulate the medulla part (Tsigos and Chrousos 2002). Previous studies have shown that, in chronic stress, the weight of the adrenal gland increased due to the increase in hyperplasia in the cerebrospinal region of the adrenal glands. This hyperplasia is due to the anterior pituitary hormone (ACTH) trophic effect on the activity of the adrenocortical fasiculatus cells, which can increase the volume and the number of these cells. Therefore, increase in the adrenal gland weight is one of the most important indicators of chronic stress (Bali and Jaggi 2015). Here, L-arginine at 1 μg/rat, that decreased the level of cortisol, increased the adrenal weight. It is proposed that VTA (Ventral tegmental area), which has a two-way communication with the NAc, is of two-way communications with locus coeruleus as the brain's noradrenaline source. The effects of locus coeruleus ultimately increase the modular activity of the adrenal gland (Mehendale et al.2004, Haghparast et al.2012, Ferrucci et al.2013). Our results showed that all doses of L-arginine increased the weight of the gland in stress conditions, especially 1 μg/rat, with probably further stimulation of the brain stem and following the increase in the adrenergic system activity in the medullary of adrenal gland. However, we did not find any scientific discussion to confirm above hypothesis and more experiences are needed to clarify the phenomena.
Influence of shift type on sleep quality of female nurses working monthly rotating shifts with cortisol awakening response as mediating variable
Published in Chronobiology International, 2018
Cortisol, which is a hormone secreted by the adrenal gland, plays a crucial role in stress responses and helps the human body adapt to its environment (Engert et al. 2013). When sleep begins, the hypothalamic–pituitary–adrenal (HPA) axis becomes inert (Marković et al. 2011). Occasional sleep loss is associated with the activation of the HPA axis, while waking up in the middle of the night is caused by the sudden release of cortisol (Chapotot et al. 2001). The cortisol awakening response (CAR) refers to a rapid increase in cortisol levels within 30–45 min of waking, which is closely related to HPA axis activity (Powell and Schlotz 2012). Shift rotations stimulate HPA axis activity in the neuroendocrine system, which disrupts the negative regulation of corticosteroids (Bostock and Steptoe 2013). Kantermann et al. (2012) posited that a negative correlation exists between the morning and pre-sleep cortisol levels of shift workers and sleep duration. Thus, shift type may also influence cortisol patterns in the body. The CAR is the most representative of an individual’s cortisol release rhythm; it plays a crucial role in activating the HPA axis during the waking process so as to help individuals face anticipated stress. Thus, it is an important physical index of adaptability to one’s environment (Clow et al. 2010). At present, the most common way of expressing the CAR is using CARi, which is the net increase in cortisol levels during the 30–45 min after waking (Park et al. 2014; Rapcencu et al. 2017).