The endocrine system consists of glands that release hormones to regulate bodily functions. The major glands include the pituitary gland, thyroid gland, parathyroid glands, pancreas, adrenal glands, and gonads. Each gland produces specific hormones that target other glands or body systems to perform functions like calcium regulation, metabolism, growth, and reproduction. Hormones travel through the bloodstream and act through receptor pathways or nuclear receptors in cells.

2. Controls many body functions - exerts control by releasing special chemical substances into the blood called hormones - Hormones affect other endocrine glands or body systems Consists of several glands located in various parts of the body. 1.Pituitary gland

4. The Pituitary Gland is divided into 2 areas Posterior Pituitary: oxytocin antidiuretic hormone ( ADH ) Anterior Pituitary: thyroid-stimulating hormone ( TSH ) growth hormone ( GH ) adrenocorticotropin ( ACTH ) follicle-stimulating hormone ( FSH ) luteinizing hormone ( LH ) prolactin

5. 2. Thyroid Gland - lies in the anterior neck just below the larynyx. - Two lobes, located on either side of the trachea, connected by a narrow band of tissue called the isthmus . - Sacs inside the gland contain colloid thyroxine ( T4 ) triiodothyronine ( T3 ) “ C” cells within the thyroid produce the hormone calcitonin .

6. Calcitonin , when released, lowers the amount of calcium in the blood. hypothyroidism, or Myxedema. hyperthyroidism, commonly called Graves’ disease. Long term hyperthyroidism: Exopthalmos bulging of the eyeballs In severe cases - a medical emergency called t hyrotoxicosis can result.

7. 3. Parathyroid Glands small, pea-shaped glands, located in the neck near the thyroid usually 4 - number can vary regulate the level of calcium in the body produce parathyroid hormone -  level of calcium in blood Hypocalcemia can result if parathyroids are removed or destroyed.

8. 4. Pancreas Islets of Langerhans specialized tissues in which the endocrine functions of the pancreas occurs include 3 types of cells: alpha (  ) beta (  ) delta (  ) each secretes an important hormone .

9. Alpha (  ) cells release glucagon , essential for controlling blood glucose levels. When blood glucose levels fall,  cells  the amount of glucagon in the blood. Beta Cells (  ) release insulin (antagonistic to glucagon). Insulin  the rate at which various body cells take up glucose. Thus, insulin lowers the blood glucose level. Delta Cells (  ) produce somatostatin , which inhibits both glucagon and insulin.

10. 5. Adrenal Glands 2 small glands that sit atop both kidneys. Each has 2 divisions, each with different functions. Adrenal Medulla catecholamine hormones norepinephrine epinephrine Adrenal Cortex steroid hormones glucocorticoids mineralocorticoids androgenic hormones

11. 6. Gonads and Ovaries the endocrine glands associated with human reproduction. Ovaries: located in the abdominal cavity adjacent to the uterus. Manufacture estrogen protesterone Testes: located in the scrotum produce sperm for reproduction Manufacture Testosterone

12. Hypothalamic Hormones/Factors Corticotropin releasing hormone (CRH)- ACTH Thyrotropin releasing hormone (TRH)- TSH Gonadotropin releasing Hormone (GnRH)- FSH,LH Prolactin release inhibiting hormone (PRIH)- Prolactin Prolactin releasing factor (PRF)- Prolactin

13. Growth hormone releasing hormone (GHRH)- GH Growth hormone releasing inhibiting Factor (GHRIF)- GH Malinocyte-stimulating hormone releasing factor (MSH-RF)- α , β & ᵞ -MSH MSH release inhibiting factor (MSH-RIF)- α , β & ᵞ -MSH

14. At cell membrane receptors a) Through alteration of intracellular cAMP concentration b) Through IP3/DAG pathway c) Tyrosin kinase pathway Adrenalin Glucagon TSH,FSH,LH,PTH ACTH Calcitonin Vesopressin(V 2 ) Vasopressin(V 1 ) Oxytocin Insulin Growth hormone Prolactin

15. Steroidal hormones Glucocorticoids Mineralocorticoids Androgens Estrogens Progestins At nuclear receptor Thyroid hormones

17. Stimuli which cause growth hormone release Fasting Hypoglycaemia Exercise Stress Gh secretion is ↓ by ↑ in plasma free fatty acids High dose of glucocorticoids β adrenergic agonist Gh secretion is ↑ by 5HT agonist α adrenergic agonist

18. Growth hormone inhibitors Somatostatin 14 amino acid Inhibit secretion of- GH TSH Prolactin Insulin Glucagon G.I secretions By pitutary By Pancreas

19. Synthetic octapeptide of somatostatin 40 times more potent Long acting Use Acromegaly Secretory diarrhoeas associated with carcinoids, AIDS, cancer chemotherapy