Endocrine System Flashcards
(10 cards)
What is a hormone?
A chemical messenger secreted by endocrine cells into the bloodstream to regulate distant target cells.
What factors affect hormone concentration?
Secretion rate (most important) and inactivation/excretion rate (e.g., by liver or kidneys).
How is hormone secretion typically regulated?
Mostly by negative feedback — the hormone or its downstream effect inhibits further secretion.
What is hormonal synergism?
When two or more hormones produce the same effect, and their combined effect is greater than the sum of their individual effects.
What is hormonal permissiveness?
When one hormone allows another to exert its full effect.
What is hormonal antagonism?
When one hormone opposes the action of another.
How does the anterior pituitary release hormones?
Hypothalamic hormones travel through a portal system to stimulate or inhibit anterior pituitary hormone secretion.
How does the posterior pituitary release hormones?
Hormones made by hypothalamic neurons are released directly into the blood from axon terminals in the posterior pituitary.
What is an example of a hormone with negative feedback?
Cortisol inhibits the release of CRH (from the hypothalamus) and ACTH (from the anterior pituitary), reducing cortisol secretion.
