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Unformatted text preview: 1 Outline 10: Hormones & Sex I. Hormones versus Neurotransmitters Neurotransmitters - released directly adjacent to the target cell Hormones - carried by the blood to targets in the body Several neurotransmitters are also considered hormones: epinephrine, norepinephrine, CCK, angiotension II. Types of Hormones A. Amino Acid derivatives (e.g., norepinephrine) B. Protein & peptide hormones (long & short chains of amino acids) Typically affect cells by the same route as peptide neurotransmitters, i.e., bind to receptors on the outer cellular membrane Most hormones released by the hypothalamus and pituitary are peptide hormones. C. Steroid hormones (all steroid hormones contain 4 carbon rings) 1. How they work in general - Typically easily pass through cellular membranes and bind to receptors in the cell cytoplasm or the nucleus -Can have both relatively fast effects (change in membrane permeability to ions) and slower effects via alterations in gene expression 2. Some steroid hormones: cortisol- released by adrenal gland corticosterone - released by adrenal gland estrogens e.g., estradiol released by gonads and by adrenal glands androgens e.g., testosterone " " " " 3. Sex steroids (also called "gonadal steroids", although they are also produced in smaller quantities by the adrenals) Androgens and estrogens commonly exert their effects by increasing the synthesis of some types of RNA and proteins (i.e. by altering gene expression) 2 Some genes activated by gonadal steroids are called "sex-limited genes ", because the effects are seen more strongly in one sex than the other e.g., estrogen effects on breast development androgen effects on facial hair Other effects are not sex limited, e.g., androgen stimulates pubic hair growth in both sexes The 2 major known sex differences in sex steroid production are : (1) females produce relatively more estrogens and males produce relatively more androgens (2) females have cycles of hormone production, males typically do not (at least do not have cycles spanning days) III. Control of hormone release A. Pituitary Gland-- The Master Gland 1. Hormones released by the Posterior Pituitary include oxytocin and vasopressin 2. Hormones released by the Anterior Pituitary : adrenocorticotropic hormone (ACTH) - controls secretions of adrenal cortex thyroid stimulating hormone (TSH) - controls secretions of the thyroid prolactin - controls secretions of the mammary glands somatotropin (aka growth hormone, GH) - promotes body growth Follicle simulating hormone (FSH) Control secretions of the gonads Luteinizing hormone (LH) " " " (aside: in males LH is sometimes called interstitial cell stimulating hormone, 2 Some genes activated by gonadal steroids are called "sex-limited genes ", because the effects are seen more strongly in one sex than the other...
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- Spring '08