Week 9 - Disorders of the Pituitary Gland and Adrenal Cortex Flashcards
Why are individuals with acromegaly likely to develop diabetes?
Acromegaly is the clinical condition caused by excess growth hormone, almost always due to a benign tumour.
Growth hormone stimulates glycolysis, inhibits glycogenesis and increases gluconeogenesis - similar actions to glucagon and adrenaline, antagonising the effects of insulin.
How does growth hormone exert most of its action? What inhibits GH release?
Growth hormone binds to its receptors on hepatocytes, which secrete insulin-like-growth-factor 1 (IGF-1). IGF-1 binds a specific receptor on cells to cause bone growth, soft tissue hyperplasia, and metabolic effects.
Somatostatin inhibits GH release.
Distinguish between Cushing disease and Cushing syndrome.
Cushing disease features from excess glucocorticoid due to a ACTH-secreting pituitary tumour.
Cushing syndrome is the constellation of signs and symptoms associated with glucocorticoid excess.
How does cortisol exert its actions?
Steroid hormones bind intracellular receptors that then bind DNA promotor regions to affect gene transcription
What is the role of glucocorticoids in the immune system?
- Cortisol is a potent anti-inflammatory hormone
- It primarily suppresses the activity of lymphocytes: reduces cytokine secretion and inhibits their proliferation
- High doses of potent exogenous glucocorticoids are used in chemotherapy against lymphoproliferative disease
How is mineralocorticoid secretion affected in pituitary failure?
Unaffected
Aldosterone secretion is mainly controlled by the renin-angiotensin system and the serum potassium concentration, rather than ACTH.
Distinguish between Cushing disease and Cushing syndrome.
Cushing disease features from excess glucocorticoid due to a ACTH-secreting pituitary tumour.
Cushing syndrome is the constellation of signs and symptoms associated with glucocorticoid excess.
How does cortisol exert its actions?
Steroid hormones bind intracellular receptors that then bind DNA promotor regions to affect gene transcription
What is the role of glucocorticoids in the immune system?
- Cortisol is a potent anti-inflammatory hormone
- It primarily suppresses the activity of lymphocytes: reduces cytokine secretion and inhibits their proliferation
- High doses of potent exogenous glucocorticoids are used in chemotherapy against lymphoproliferative disease
How is mineralocorticoid secretion affected in pituitary failure?
Unaffected
Aldosterone secretion is mainly controlled by the renin-angiotensin system and the serum potassium concentration, rather than ACTH.
