Health Psychology, 2nd Edition

LH) as well as stimulating lactation (through the release of oxytocin) and maintaining
blood pressure (through the release of vasopressin). However, it also releases ACTH
(after stimulation by the hypothalamus), which stimulates the adrenal cortex – this is
known as the hypothalamic–pituitary–adrenal (HPA) axis response. This is a most
important response system, which we consider in some detail shortly.

The adrenal glands

There are two adrenal glands located on the top of each kidney (see Figure 2.2).
The adrenal glands are best considered as being two glands within one. Each has a
central core, called the adrenal medulla, which secretes the hormones adrenaline and
noradrenaline (also known as epinephrine and norepinephrine), which act on the visceral
organs in the same way as neurons in the nervous system. In other words, they increase

BIOPSYCHOSOCIAL PATHWAYS 21

FIGURE 2.2Continued

Constricts pupils

Stimulates flow

of saliva

Constricts bronchi

Slows heartbeat

Stimulates peristalsis

and secretion

Stimulates bile

release

Contracts bladder

Contracts bladder

bladder

bladder

bladder

bladder

bladder