1. Endocrine System Biology 2122

2. Introduction (1) What are hormones? (2) What are the functions of hormones? (3) What are the types of hormones? – Amino Acids – Steroids – Eicosanoids

3. How do Hormones Work? (1) Action on Target Cells – Membrane permeability – Synthesis of proteins or enzymes Or inhibits – Induces secretory activity – Stimulates mitosis (2) Target-Specific – Target cell receptor sites – “Turns on cell” – “Dynamic”

4. How do Hormones Work? (3) Half-Life (4) Interaction – Target Cells – Permissive – Synergistic – Antagonistic (5) Control of Release – Negative feedback – Endocrine Gland Stimuli Humoral stimuli Neural stimuli Hormonal stimuli

5. Plasma Membrane Receptors (1) Second Messenger System – All amino acid hormones (except thyroid)

6. Plasma Membrane Receptors (2) Intracellular – Direct Gene Activation – Lipid soluble; steroid – Binds to intracellular receptors – Binds to DNA – Activates a gene

7. (1). Somatotroph cells produce GH (2). Secretion – GHRH – stimulates release (GHIH) inhibits – Produced in the hypothalamus (3). Effects – Anabolic – protein synthesis – Targets bones and muscles – Stimulates epiphyseal plates during development (4). Disorders – Gigantism and Acromegaly Anterior Pituitary Hormones-HGH

8. (1). Also referred to as thyrotropin. – Produced by thyrotroph cells (2). Secretion – TRH or thyrotropin releasing hormone stimulates the release of TSH – Negative feedback – rising levels of thyroid hormones ANIMATION (3). Effects – Moderates normal thyroid gland activity. Thyroid-Stimulating Hormone

9. (1). ACTH – adrenocorticotropic hormone secreted – corticotroph cells (2). Stimulation-Secretion – CRH – corticotropin-releasing hormone – hypothalamus Levels peak in the morning – Negative feedback (3). Effects – Stimulates the Adrenal gland (cortex) to release Glucocorticoids Cortisol (stress hormone) Adrenocorticotropic Hormones

10.  (1). FSH and LH – gonadotrophic cells  (2). Stimulus-Secretion ◦ Puberty ◦ GnRH – prompts the anterior pituitary to release hormones ◦ ANIMATION ANIMATION  (3). Effects ◦ (a). LH  FSH - maturation of follicle  Ovulation  Stimulates interstitial cells - testosterone in males ◦ (b). FSH – stimulates gamete production; follicle development. Gonadotropins

11. (1). PRL or prolactin is a protein hormone. –P–Produced by the lactrotroph cells (2). Stimulus – Secretion –P–PRH and PRH –P–PRH plays dominant role – dopamine prevents secretion (3). Effects –S–Stimulate milk production in the breasts Prolactin

12. Acromegaly

13. (1). Production- hypothalamic neurons (2). ADH or Antidiuretic Hormone – Reabsorption of water – collecting tubules – Release stimulated by – increasing osmolarity Diabetes insipidus (3). Oxytocin – Stimulated release by positive feedback – contractions during birth – Milk ejection – Synthetic – induce contractions Posterior Pituitary Gland Hormones

14. (1). Produces TH or thyroid hormones ◦ T 4 or thyroxin; T 3 or triiodonthyronine (2). Stimulus – Secretion ◦ Hypothalamus (TRH) -  Pituitary (TSH) --  TH ◦ Stress - cold, pregnancy – cause hypothalamus to produce TRH. ◦ Rising TH levels – negative feedback to hypothalamus-pituitary axis. (3). Effects ◦ Increases BMR ◦ body heat production (stimulates enzymes to increase glucose oxidation) Thyroid Gland

15. Synthesis of TH

16. (1). Myxedema – hypothyroid (2). Goiter (3). Cretinism – Infant hypothyroidism (4). Grave’s Disease – Hyperthyroid Thyroid Imbalances

17. (1). Polypeptide hormone – Parafollicular cells of the thyroid – Lowers calcium blood levels – Reabsorption back into the bones (2). Stimulus for release – 20% above normal levels for calcium blood levels – Lower than normal – inhibitory effect (3). More important in childhood – Due to developing bones and keeps calcium levels in check Calcitonin

18. (1). Cells in the parathyroid gland – Oxyphil and chief cells (secretes ) PTH (2). Stimulus and Secretion – Hypocalcemia -----  PTH Parathyroid Hormones Bone Osteoclast activity increased Intestines Increases calcium absorption Kidney Increases calcium reabsorption

19. (1). Adrenal gland has two distinct regions ◦ (a). Cortex - outer region ◦ (b). Medulla - inner region (2). Hormones produced – corticosteroids ◦ 12 total (3). Steroid Hormones – Not stored in cells – rate of release depends on productivity (4). Cortical regions ◦ (a). Zona glomerulosa – mineralocorticoids ◦ (b). Zona fasciculata – glucocorticoids ◦ (c). Zona reticualaris – adrenal sex hormones called gonadocorticoids. Adrenal Hormones

20. (1). Produced in the zona glomerulosa of the cortex ◦ Mostly aldosterone ◦ Balances ions and water (2). Stimulus and Secretion ◦ Renin-angiotensin mechanism ◦ Elevated K+ levels (3). Disorders ◦ Aldosteronism ◦ Addison’s disease Mineralocorticoids

21. (1). Produced in the zona fasciculata – Metabolic hormones (2). Cortisol is the main hormone – Gluconeogenesis; lipolysis; protein metabolism (3). Stimulation and secretion – ACTH from the anterior pituitary (low levels of hormones) (4). Disorders – Cushing’s syndrome – Addison’s disease Glucocorticoids

22. (1). Androgens produced in the zona reticularis – Converted to testosterone and estrogen (2). Stimulus and secretion – ACTH released from anterior pituitary (3). Effects – Males – Female libido; pubic and axillary hair in females; estrogen after menopause Gonadocorticoids