permissive effect: h action requires recent/simultaneous exposure to a second h | synergistic effect: more than one h produces same action, and combined effects are larger than solo effects | antagonistic effect: one h opposes actions of a second h
amine hormones
S/are synthesized by modifying certain amino acids | always retain an amino group: NH3+
peptide v. protein hormones
peptide hormones consist of 3-49 amino acids | protein hormones consist of 50-200 amino acids
hormone
a molecule that is released in one part of the body but regulates the activity of cells in other parts of the body | the human body has approx 50 types
lipid-soluble hormones
bind to receptors within target cells | EX/steroid hormones, thyroid hormones, nitric oxide
transport proteins
most l-s h molecules travel in blood bound to ----- | L/synthesized in liver | F/make l-s hormones temporarily w-s; retard passage of small hormone molecules through kidney filters, thus slowing rate of h loss; provide ready reserve of h in bloodstream
general pattern of lipid-soluble hormone action
enter cell | bind to receptor | h-receptor complex alters cell's gene expression | new mRNA forms, enters cytosol, directs synthesis of a new protein, often an enzyme, on the ribosomes
organs and tissues that contain hormone-secreting cells
first messenger binds to receptor on membrane | binding causes adenylate cyclase to convert ATP into cyclic AMP | cAMP activates several enzymes | activated enzymes catalyze physiological responses
