Key Terms
Scope of control
Growth, metabolism, reproduction, stress response, water balance, blood glucose, calcium regulation.
Primary class
Steroid hormones.
Example
TSH from anterior pituitary stimulates thyroid to release T3 and T4. Rising T3/T4 levels feed back to hypothalamus and a
Signal cascade
1. Hormone binds receptor.
Up-regulation
Prolonged low hormone levels cause the cell to increase receptor numbers; cell becomes more sensitive.
Down-regulation
Rising hormone levels cause the cell to decrease receptor numbers; cell becomes less responsive.
Humoral stimuli
Change in blood chemistry triggers hormone release.
Hormonal stimuli
One hormone triggers release of another hormone.
Neural stimuli
Nervous system directly signals an endocrine gland to release hormones.
RAAS cascade (tested frequently)
Low blood pressure detected by kidneys → kidneys release renin → renin cleaves angiotensinogen (liver protein) into angi
Function
Control basal metabolic rate. Affect nearly all cells except adult brain, uterus, testes, blood cells, and spleen.
Production pathway
TSH from anterior pituitary → follicle cells of thyroid → thyroglobulin + iodine → T3 and T4. Iodine concentrated in thy
Negative feedback
Rising T3/T4 inhibit both hypothalamus and anterior pituitary; TSH drops.
Iodine deficiency
Cannot synthesize T3/T4. TSH keeps rising with no result.
Hypothyroidism
Low metabolic rate; weight gain; cold sensitivity; reduced mental activity. In children: cretinism (intellectual and gro