Endocrine System

1. Endocrine System Hank

2. Word parts • -crin: to secrete • Diuret-: to pass urine • Endo-: within • Exo-: outside • Hyper-: above • Hypo-: below • Para-: beside • Toc-: birth • -tropic: influencing

3. Vocabulary • Hormones: substances secreted by the endocrine system and enter the blood stream, acting on target cells • Targetcells: cells with specific receptors on which hormones can take action • Paracrinesecretions: affect only neighboring cells • Autocrinesecretions: affect only the secreting cell

4. Characteristics of the Endocrine System • Uses chemical signals that bind to receptor molecules • Help regulate metabolic processes • Control the rate of chemical reactions • Transport substances across cell membranes • Regulate water and electrolyte balances • Produce hormones

6. Hormones • Steroids: formed from cholesterol • Examples: estrogen, testosterone, aldosterone, cortisol • Amines: formed from amino acids • Examples: norepinephrine and epinephrine • Peptides: formed from amino acids • Examples: antidiuretics, oxytocin, thyrotrophin • Proteins: formed from amino acids • Examples: parathyroid hormone, growth hormone, Glycoproteins: formed from a protein and a carbohydrate • Examples: follicle-stimulating hormone, luteinizing hormone, thyroid stimulating hormone

7. Steroid Hormones • Carried in the bloodstream • Soluble in lipids (oils) • Can diffuse across cell membranes • Activates genes on DNA to make proteins

8. Non-steroid Hormones • Amines, peptides and proteins • Bind to receptors in target cell membranes • Delivers a message to the target cell (signal transduction) • Starts a biochemical chain reaction to alter cell processes

9. Prostaglandins • Prostaglandins: a group of biochemicals that regulate cells • Produced by the liver, kidneys, heart, lungs, thymus, pancreas, brain, and reproductive organs • Very potent and synthesized just before they are released • Act locally, not over the entire body

10. Control of Hormone Secretions • The hypothalamus regulates the pituitary gland’s release of hormones that stimulate other glands to release hormones • The nervous system stimulates glands directly Ex: adrenaline being released in times of panic 3. Glands respond directly to changes in the internal environment Ex: Insulin being released when blood glucose levels are high

11. The Pituitary Gland • ThePituitarygland: (hypophysis) located at the base of the brain in the hypothalamus • Controlled by the brain • Each hormone acts on a specific group of cells • Some hormones inhibit actions but most stimulate actions to happen

12. Growth Hormone • GrowthHormone (GH): stimulates cells to increase in size and divide • Speeds up the rate of cellular metabolism • Nutrition affects the amount of growth hormone available

13. Hormones in the Pituitary Gland • Prolactin (PRL): stimulates a woman’s milk production in women and maintains normal sperm production in men • Thyroid-stimulatinghormone (TSH): controls the thyroid excretions • AdrenocorticotropicHormone (ACTH): controls the production and secretion of hormones in the adrenal gland

14. Hormones of the Pituitary Gland • Follicle-stimulatingHormone (FSH) and LuteinizingHormone (LH): hormones of the reproductive organs • Ovaries: stimulates release of egg into the uterine tube • Testes: stimulates production of sperm • AntidiureticHormone (ADH): regulates the water concentration of body fluids • Oxytocin (OT): contracts smooth muscles in the uterus and stretches the cervix and the birth canal during childbirth

15. Thyroid Gland • ThyroidGland: secretes hormones that will be released into the blood stream at a later time • Thyroxine (T₃) and triiodothyronine (T₄): help regulate the metabolism of carbohydrates, lipids and proteins • Have a lot of iodine in them • Calcitonin: regulates the concentrations of blood calcium and phosphorus

16. Parathyroid Glands • ParathyroidGlands: located beside the thyroid glands • ParathyroidHormone (PTH): increases blood calcium and phosphorus concentrations • Affects bones: stimulates osteoclasts and inhibits osteoblasts • Affects kidneys: stimulates kidneys to conserve calcium and release phosphorus • Affects intestines: stimulates calcium absorption from food

17. Adrenal Glands • AdrenalGlands: a mass of adipose tissue near the kidneys • Epinephrine and norepinephrine: have long lasting effects • Increase heart rate, breathing rate and blood glucose levels • “Fight-or-flight” response

18. Adrenal Gland • Aldosterone: helps regulate the concentration of mineral salts • Conserves sodium and excretes potassium • Stimulates water conservation • Secreted if blood pressure falls too low

19. Adrenal Gland • Cortisol: affects glucose metabolism and influences protein and fat metabolism • Keeps blood sugar levels normal between meals • AdrenalSexHormones: Stimulated at early development of reproductive organs • androgens: male and estrogens: female • found in the skin, liver and adipose tissue

20. Pancreas • Pancreas: has both exocrine and endocrine glands • Exocrine: secrete digestive juices • Endocrine: secrete hormones • Glucagon: stimulates the liver to break down glycogen and convert amino acids into glucose to RAISE blood sugar levels • Insulin: stimulates the liver to form glycogen from glucose to LOWER blood sugar levels

21. Other Glands • PinealGland: secretes melatonin when it gets dark • Melatonin: acts on regions of the brain that function as the “biological clock” • Regulates your day and night cycles • Thymus: in the lungs and secretes thymosins • Thymosins: affect the production of white blood cells