2. 1 Endocrine System Modified from: http://www2.kumc.edu/instruction/nursing/nrsg812/endocrine/ Images from: http://www.endocrineweb.com/ gened.emc.maricopa.edu/bio/bio181/BIOBK/BioBookENDOCR.html

3. 2 Mechanisms of Hormone Action Certain secretory cells release chemical agents (hormones) for the purpose of mediating biologic responses in distant Target Cells. Hormones sources –Single amino acid (catecholamines) –Chains amino acids (peptide hormones of hypothalamus) –Cholesterol (steroids)

4. 3 Mechanisms of Hormone Action Hormones control and integrate many body functions with this system. In general, hormonal control regulates the metabolic functions of the body, the types of effects that occur inside the cell and determined the character of the cell itself. The endocrine system works with the nervous system to regulate: metabolism, water and salt balance, blood pressure, response to stress, and sexual reproduction.

5. 4 3 Forms of Hormonal Communication 1. Endocrine = hormones are secreted into blood to regulate the function of distant target cell 2. Paracrine = endocrine cells secrete into surrounding extracellular space. Target cells are neighbors 3. Neuroendocrine = Directly into blood (norepin), & into brain interstitial space (Vasopressin)

6. 5 Endocrine System Endocrine System Hormones/Glands whose functions are solely endocrine include: pituitary (hypophysis) pineal thyroid parathyroids adrenals pancreas

7. 6 Hypothalamus and Pituitary Pituitary has direct neural and blood connection to the hypothalamus Hypothalamus sends releasing factors to anterior pituitary Hypothalamus stimulates posterior pituitary via neural pathway

8. 7 Hypothalamus Hypothalamus can synthesize and release hormones from its axon terminals into the blood circulation. controls pituitary function and thus has an important, indirect influence on the other glands of the endocrine system. exerts direct control over both the anterior and posterior portions of the pituitary gland. regulates pituitary activity through two pathways: a neural pathway and a portal venous pathway.

9. 8 Hypothalamus Neural pathways extend from the hypothalamus to the posterior pituitary lobe, where the hormones are stored and secreted. Portal venous pathways connect the hypothalamus to the anterior pituitary lobe, carry releasing and inhibiting hormones

10. 9 Pituitary Gland Pituitary Gland is located at the base of the skull in an indentation of the sphenoid bone. Is joined to the hypothalamus by the pituitary stalk (neurohypophyseal tract) and consists of the anterior pituitary and the posterior pituitary

11. 10 Anterior pituitary gland (adenohypophysis) Called the master gland, because its anterior lobe has direct control over the secretion of: ADH - antidiuretic hormone (vasopressin) ACTH - adrenocorticotrophic hormone TTH - thyrotrophic hormone GH - growth hormone FSH - follicle stimulating hormone LH - leutinizing hormone

12. 11 Posterior pituitary Stores and secretes hormones made in the hypothalamus and contains many nerve fibers. ADH (Antidiuretic Hormone/Vasopressin), which controls the rate of water excretion into the urine Regulates Na+ & K+ reabsorption in the kidneys this influences blood volume & blood pressure Oxytocin, which, among other functions, helps deliver milk from the glands of the breast.

13. 12 Adrenal Glands Adrenal Glands have an outer cortex and an inner medulla. The adrenal cortex and medulla are major factors in the body's response to stress.

14. 13 Kidneys—Renal Hormones Renin is an hormone/enzyme (released from juxtaglomerular cells)

15. 14 Thyroid Gland Thyroid function is regulated by the hypothalamus and pituitary, feedback controls an intrinsic regulator mechanism

16. 15 Thyroid Problems Thyroid gland enlargement may or may not be associated with abnormal hormone secretion. An enlarged thyroid gland can be the result of: iodine deficiency (Goiter) inflammation, or benign or malignant tumors

17. 16 Parathyroid Glands There are 4 parathyroid glands located behind the thyroid. Parathyroid Glands are important in calcium metabolism phosphorus metabolism

18. 17 Pancreas endocrine gland, secreting the hormones insulin and glucagon, exocrine gland, producing digestive enzymes. Secretes insulin, glucagon (regulate blood sugar)

19. 18 Cellular Mechanisms of Hormone Action Hormonal interaction with target cells begin with reversible binding to specific receptors 1. Interactions with membrane receptor (protein) 2. Interactions with nuclear receptors (steroid)

20. 19 Amino Acid Based Hormones Bind to receptor sites on cell membranes Amino acid hormone binding causes changes to occur receptor can activate carrier molecules which transport substances across the membrane receptor can activate second messengers

21. 20 Second Messengers Second Messengers set a series of reactions in motion Activate adenylate cyclase, generates cAMP from ATP cAMP activates other proteins within the cell increases glycogenolysis & lipolysis Open Ca2+ ion channels, activates calmodulin Hydrolyzes phospholipase C into inositol triphosphate & diacylglycerol

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23. 22 Steroid Hormones Steroid hormones are produced by chemical modification of cholesterol Major classes steroid hormones glucocorticoids (cortisol) mineralocorticoids (aldosterone) androgens (testosterone) estrogens (estradiol) Vitamin D metabolites

24. 23 Steroid Hormones Diffuse into cell and influence DNA Bind to a protein associated with DNA Cause DNA to increase synthesis of specific amino acids

25. 24 Feedback Loops The release of a hormone is often triggered by a change in the concentration of some substance in the body fluids. Each hormone has a corrective effect, eliminating the stimulus, which then leads to a reduction in hormone secretion. This process is called a negative feedback homeostatic control system to keep hormones at normal levels. (if levels increased it would be called positive feedback)

26. 25 Blood Sugar Control Insulin and glucagon are produced by small groups of cells in the pancreas (islets of Langerhans). Beta cell make insulin (beta cells) and Alpha cells that make glucagon Insulin is released when the blood sugar rises too high. Insulin tells the cells to use sugar. Glucagon is produced when the blood sugar is falling too low. Glucagon tells the liver to release sugar that was stored there when the blood sugar was higher.