Endocrine CBL: Cortisol

Where is cortisol synthesised and secreted?

• Cortisol is synthesized in the adrenal cortex, in the zona fasciculata, one of the layers of the adrenal glands located on top of the kidneys.

• cortisol is secreted by from the adrenal glands

What hormone type is cortisol?

• glucocorticoid hormone

What is the function of cortisol?

• manages stress

• maintains blood pressure and cardiovascular reactivity

• responsible for regulating gluconeogenesis and glycogenolysis

• regulates immunological and inflammatory responses

• regulates cognitive function, memory, sleep and mood

• inhibits osteoblast function

• stimulates lipolysis in adipose tissues and increases free fatty acids

What can induce rising cortisol levels?

• stress, septicaemia, hypoglycaemic conditions or severely low blood pressure or going through a surgery - all of these release cortisol

What happens when cortisol is secreted in excess by the adrenal glands?

• it has a direct feedback to the anterior pituitary gland, asking it to shut down the ACTH levels and also has a feedback directly to the hypothalamus telling it to shut down CRH secretion

What hormones regulate cortisol secretion?

• (Corticotrophin releasing hormone) Released by the hypothalamus

• CRH stimulates the anterior pituitary to release adrenocorticotropic hormone (ACTH),

• which in turn prompts the adrenal cortex to secrete cortisol

CRH production in (hypothalamus) → stimulates release of ACTH (anterior pituitary) → prompts secretion of cortisol (adrenal glands)

When are cortisol levels highest?

Between 8-9am in the morning

When do cortisol levels decrease?

after midday until midnight then they start to rise untl they reach their peak at 8am