One of the two major systems that are affected by the stress response is the which results in increased production and/or secretion of corticotrophin-releasing factor, adrenocorticotropic hormone, and cortisol.

The two major systems involved in the stress response are the Nervous System [the Sympathetic subdivision of the Autonomic Nervous System (ANS)] and the Endocrine System (glands which secrete hormones intonthe bloodstream).
The Endocrine System's response during acute and/or chronic stress (adaptation) involves first the Hypothalamic release of Corticotropin-Releasing Hormone (CRH), which stimulates the Anterior Pituitary (via the blood) to release AdrenoCorticoTropic Hormone (ACTH), which then activates the Adrenal Cortex to release glucocorticoid hormones (i.e. Cortisol), amongst others into the bloodstream. Cortisol then has many effects on tissues and organs throughout the body to allow better generalized coping with the initial stress stimulus.

The basic repeating unit of nucleic acids are known as nucleotides. a nucleotide consists of three distinct chemical groups.