ENDOCRINE - Chemical Signals: The Endocrine System I. Types...

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Chemical Signals: The Endocrine System I. Types of Chemical Signals A. Pheromones : secreted by exocrine glands; targets external to the body. A. Local regulators or local hormones : 1. paracrines: Transport is by simple diffusion to surrounding cells. Solely affect cells w/ receptors a. Histamines- trigger allergic response cause blood vessels to vasodilation b. Prostaglandins-throughout body, made of fatty acids, involved in a wide variety of responses/aspirin-prostaglandin inhibitor c. nitrous oxide (NO): present in most mammalian tissues; rapid but short- lasting effects. Involved in smooth muscle relaxation, penile erection, immune responses, and can act as a ‘sort of’ neurotansmitter. 2. neurocrine: neurotransmitters are chemical signals directly to an adjacent cell. B. Hormones : secreted by endocrine glands and transported by circulatory system (blood) to distant targets. Two basic hormone types are amino-acid based and steroids. 1. peptide hormones: polypeptide or protein hormones; lipophobic; examples include insulin and glucagon. 2. Amines (made from tyrosine) released from thyroid and adrenal cortex a. catecholamines: epinephrine(adrenaline) and norepinephrine(like epinepherin); lipophobic(hydrophilic)-don’t dissolve in fat b. thyroid hormones: thyroxine; lipophilic(hydrophobic)-dissolve in fat 3. Steroids: made from cholesterol; lipophilic; sex hormones and adrenocorticocoids(aldosterone , progesterone, testosterone, estrogen
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ENDOCRINE - Chemical Signals: The Endocrine System I. Types...

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