Physiology of Stress

When a stressor is sensed by an animal, messages are received by the hypothalmic area of the brain. The hypothalamus responds in two different ways (see diagram below):

1. Nerve impulses are passed along the sympathetic nervous system to the adrenal medulla, which in turn increases secretion and synthesis of the hormone adrenaline and noradrenaline. Adrenaline prepares the body for fight or flight; increases blood sugar, vasoconstriction and increases blood pressure, increases respiratory rate, increases muscle tone, increases nerve sensitivity.

2. A releasing factor is passed from the hypothalamus into the anterior pituitary gland which in turn increases ACTH (adreno-cortico-tropic-hormone) which in turn causes the adrenal cortex to secrete steroid hormones or “corticoids” which have a number of physiological effects; increases metabolic rate, break down of fatty acids and protein, antibody production decreases, reproductive capacity decreases, ulceration of the stomach and intestinal tract.

The first pathway is based on the nervous system and is almost instantaneous. The second pathway is based on hormones and may take minutes or hours before responses are apparent.


Source: http://www.s-cool.co.uk/a-level/psychology/stress/revise-it/what-is-stress ;


Last modified: Saturday, 28 January 2023, 10:07 AM