Humoral stress pathway

The adrenal gland produces cortisol in response to intermediate hormones, called adrenocorticotropin hormone (ACTH) and corticotropin-releasing hormone (CRH) via the humoral stress pathway, which extends from the brain to the adrenals (Figure 50-2). Once the body has received an environmental stress signal, it is detected by neurons in the cerebral cortex and transmitted to the hypothalamus. The hypothalamus then releases CRH via the classic secretory pathway into the anterior pituitary. CRH stimulates release of... 

Figure 50-2. Induction of the humoral stress pathway. Once an environmental stress is detected by the CNS, this signals the hypothalamus to release CRH into the anterior pituitary. ACTH is then released from the pituitary into the blood and eventually binds membrane receptors in cells of the adrenal cortex. Cortisol is synthesized and leaves the cell via free diffusion into the blood and is eventually distributed to the hypothalamus and pituitary to inhibit release of CRH and ACTH, respectively, through a negative feedback loop.

A. The humoral stress pathway can no longer regulate cortisol levels via a negative feedback loop. 

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