Endocrine System

1. Endocrine System

2. What is the endocrine system? • Second great controlling system of the body • Body system that contains internal organs that secrete hormones.

3. So, what is a hormone? • Slowly acting chemical messenger that is released into the blood

4. So, where do hormones work? • So glad you asked that question! • Target cells or target organs • Location where a given hormone affects

5. What do hormones do? • Hormones cause certain changes. • What are these changes? • Changes in plasma membrane permeability or electrical state • Synthesis of proteins or certain regulatory molecules (enzymes) in the cell. • Activation or inactivation of enzymes • Stimulation of mitosis

6. In English please… • Hormones control all activities in the body • They alter or change functions of cell to get a response

7. 3 types of hormones • Steroidal Hormones • Insoluble in water, carried in the blood and released near the vicinity of the target cell • Nonsteriodal hormones • Unable to enter target cells and instead bind to receptors situation on the target cell’s plasma membrane • Prostaglandins • act locally, affecting only the organ where they are produced

8. What controls hormones? • Negative feedback • The chief means of regulating blood levels of nearly all hormones • Triggered by some internal or external stimulus • Rising hormone levels inhibit further hormone release • In other words, a stimuli triggers hormone production… then that hormone may either stimulate or inhibit other hormones

9. Major Endocrine Organs • Pituitary • Thyroid • Parathyroid • Adrenal • Pineal • Thymus • Pancreas • Gonads

10. Pituitary • Structure • Size of grape • Located at the base of the brain • Attached to the hypothalamus • 2 parts • Anterior pituitary • Posterior pituitary • Function • Often called the “master gland” because of its great influence on the body organs

11. Hormones of the Anterior Pituitary Gland • Prolactin (PRL) • Stimulates milk production in women after childbirth • Can affect sex hormone levels in men and women • Growth hormone (GH) • Stimulates growth in childhood • Important for maintaining healthy body composition • In adults, important for muscle mass, bone mass, and fat distribution • Adrenocorticotrophin (ACTH) • Stimulates production of cortisol (“stress hormone”) by adrenal gland. Helps maintain blood pressue and blood glucose levels

12. More… • Thyroid stimulating hormone (TSH) • Stimulates thyroid to produce thyroid hormones • Thyroid hormones – regulate metabolism, energy, growth, and development • Lutenizinghomone (LH) • Regulates testosterone in men and estrogen in women • Follicle Stimulating hormone (FSH) • Promotes sperm production in men • Stimulates ovaries to release eggs (ovulate) in women

13. Posterior Pituitary Hormones • Oxytocin • Causes milk letdown in nursing mothers and contractions during childbirth • Antidiuretic hormone (ADH) • Regulates water balance • If not secreted properly can lead to kidney problems and too much sodium

14. Thyroid Gland • Structure • Small gland in back of neck • In front of trachea and below Adam’s apple • Function • Controls metabolism

15. Thyroid Gland Hormones • Thyroxin • Increase rate at which cells release energy from carbs • Calcitonin • Regulates the blood concentration of calcium

16. Thyroid Disorders • Hypothyroidism • Stunted growth • Mental retardation • Sluggish • Weight gain in adults • Hyperthyroidism (Grave’s disease) • Restlessness • Weight loss • Anxiety • Can cause Goiter (enlarged thyroid)

17. Parathyroid gland • Structure • Behind thyroid • Four tiny glands • Function • Help maintain calcium and phosphorus levels

18. Parathyroid Hormones • Parathyroid hormone (PTH) • Takes calcium from bones to make it available in the blood

19. Parathyroid disorders • Hyperparathyroidism • Can be caused by a tumor • Increases PTH secretion • Bones soften • Too much calcium can cause kidney stones • Hypoparathyroidsm • Too little PTH • Too little calcium affects nervous system

20. Adrenal Glands • Structure • 2 organs… 1 located above each kidney • Function • Outer portion called adrenal cortex and are essential for life • Inner portion is the adrenal medulla and are not essential for life

21. Hormones of the Adrenal Medulla • Epinephrine & Norepinephrine • Increased heart rate, breathing rate, elevated blood pressure (fight or flight response to stress)

22. Hormones of the Adrenal Cortex • Aldosterone • Helps kidneys conserve sodium and excrete potassium, maintaining blood pressure • Cortisol • Keeps blood glucose stable • Adrenal Sex Hormones • Androgens (male) and estrogens (women)

23. Adrenal Disorders • Cushing’s Syndrome • Hypersecretion of cortisol • Blood glucose remains high, retains too much sodium, puffy skin, masculinzing effects in women • Addison’s Disease • Hyposecretion • Decreased blood sodium, dehydration, low blood pressure, increased skin pigmentation

24. Pancreas • Structure • Large gland behind stomach • Function • Helps body maintain healthy blood sugar levels • Contains islands of cells called islets of Langerhans which secrete glucagon and insulin

25. Hormones of Pancreas • Glucagon • Stimulates liver to break down glycogen, raises blood sugar • Insulin • Decreases blood sugar concentrations, affects the uptake of glucose cells

26. Disorders Related to the Pancreas • Diabetes Mellitus • Results from an insulin deficiency, blood sugar rises and excess is excreted in the urine • Type I • Insulin dependent; often inherited immune disorder that destroys pancreatic cells • Type II • Can be controlled with diet and exercise • Hypoglycemia • Low blood sugar; can be caused by too much insulin

27. Pineal Gland • Located between the cerebral hemispheres • Secretes melatonin • Important for maintaining Circadian rhythums (light and dark activity)

28. Thymus Gland • Large in young children • Gradually shrinks with age • Secretes thymosins – important to immune function

29. Reproductive Glands • Testes and ovaries • Testosterone, progesterone, estrogen