The Endocrine System

1. The Endocrine System

2. The Endocrine System • Chemical messages (hormones) are released into the bloodstream • Some of the major processes controlled by hormones include… • Reproduction • Growth and Development • Body Defense • Maintaining Homeostasis • Regulating Metabolism

3. What are Hormones? • Hormones are produced by specialized cells • Cells secrete hormones into extracellular fluids (blood, lymph) • Blood transfers hormones to target sites • These hormones regulate the activity of other cells!

4. What are Hormones? • Two major chemical classifications of hormones • Amino acid-based hormones • Examples: proteins, peptides, amines • Steroids: made from cholesterol

5. What do Hormones cause? • Synthesis of proteins, such as enzymes • Activation or inactivation of enzymes • Stimulation of mitosis • Changes in the plasma membrane • These changes all have one common goal – to cause some larger, long-lasting change in the body!

6. What causes Hormones to be Released? • Some sort of stimulus will trigger hormones to be released! • Hormonal Stimulus • Some hormones released will stimulate other hormones to be released

7. What causes Hormones to be Released? • Humoral Stimulus • Changing blood levels of ions & nutrients will stimulate hormones to be released • Examples: Low blood Ca2+ causes Parathyroid hormone (PTH) to release Ca2+ from bone into blood. • ADH will cause water to be reabsorbed into blood

8. What causes Hormones to be Released? • Neural Stimulus • Nerve fibers stimulate hormones to be released • Examples: norepinephrine and epinephrine released during stress

9. What are some of the major endocrine organs?

10. Endocrine Organs • Hypothalamus • Found in brain • Releases hormones that regulate the pituitary gland

11. Endocrine Organs • Pituitary Gland • Hangs from hypothalamus, broken into two lobes • Releases hormones to control other glands • Hormones released by the two lobes include…

12. Endocrine Organs • Posterior Lobe • Oxytocin: contraction of uterus, release of milk • Antidiuretic hormone (ADH): reabsorption of water by kidneys • Anterior Lobe • Prolactin: milk production • Follicle-Stimulating Hormone (FSH): production of ova and sperm • Lutenizing Hormone (LH): stimulates ovaries and testes • Thyroid Stimulating Hormone (TSH): stimulates thyroid gland • Growth Hormone (GH): stimulates growth, especially of bones and muscles

13. Endocrine Organs • Gigantism • Most of the tallest people in the world are so because they have a tumor on their pituitary gland • This causes an overproduction of GH

14. Leonid Stadnyk – 8 ft 5 in

15. Robert Wadlow – 8 ft 11 in • Tallest man ever on record • Lived to be only 22

16. Endocrine Organs • Pineal Gland • Found in brain • Produces Melatonin, which helps establish day/night cycle

17. Endocrine Organs • Thyroid Gland • Found at base of throat • Produces Thyroid Hormone, which controls the rate at which glucose is used & converted to body heat and energy

18. Endocrine Organs • Hyperthyroidism: overactive thyroid • Produce too much thyroid hormone • Symptoms include increased heart beat, tremors, weight loss, and diarrhea • Hypothyroidism: underactive thyroid • Produce too little thyroid hormone • Can be brought on by iodine deficiency or genetics • Symptoms include poor muscle tone, fatigue, decreased heart beat, weight gain, and constipation

19. Endocrine Organs • Parathyroid • Tiny gland masses on the back of the thyroid gland • Produces Parathyroid Hormone (PTH), which controls calcium release from the bones into the blood

20. Endocrine Organs • Thymus • Sits right above heart in the upper chest • Produces Thymosin, which helps mature T cells (immunity)

21. Endocrine Organs • Adrenal Glands • Sits on top of the kidneys • Produce Aldosterone, which helps with water balance of urine/blood • Produce Glucocorticoids, which increase blood glucose levels • Produce Epinephrine/Norepinephrine, which helps with short-term stresses • Some sex hormones also made here

22. Endocrine Organs • Pancreas • Located at curvature of duodenum just underneath the stomach • While produces enzymes that help with digestion, it also produces hormones such as… • Insulin, which increases ability of cells to transport glucose across their plasma membranes, thereby reducing glucose levels of blood

23. Diabetes • There are generally two types of diabetes • Type 1/ Juvenile • Pancreas self-destructs, causing lack of production of insulin. • Without insulin, sugar can not be absorbed by the body • Symptoms of Type 1 diabetes (when not treated!) are • Very high blood sugar • Weight loss • 3 ‘Ps’ • Polydipsia - Excessive thirst • Polyphagia - Excessive hunger • Polyuria - Excessive urination

24. Type 1 • Treatment of Type 1 diabetes • Diet • Daily Insulin Injections • Or -- • Insulin pump that continuously releases insulin into body.

25. Diabetes • Type 2 / Adult Onset • Body cells become resistant to insulin • Or • Pancreas is not producing enough insulin • Symptoms of Type 2 diabetes (when not treated) are • Moderately high blood glucose levels • Polydipsia, Polyphagia & polyuria (3Ps) • When glucose flushes out of body along with water, resulting dehydration. • Because glucose is unavailable, the body will use fats and proteins for energy instead which can cause weight loss.

26. Diabetes • Treatment of type 2 diabetes • Diet • Reduce the amount of sugar in diet and encourage weight loss • Oral medications that help • increase absorption of sugar • increase production of insulin • decrease release of internal glucose stores • Lastly, insulin injection if all above fail.

30. Endocrine Organs • Gonads • Male: Testes • Produces Androgen hormones (especially Testosterone), which promotes male sex characteristics and helps sperm production • Stimulated to be released b/c of Lutenizing Hormone (LH) • Female: Ovaries • Produces Estrogen, which promotes female sex characteristics, stimulates growth of uterine lining • Stimulated to be released b/c of Follicle-Stimulating Hormone (FSH) • Produces Progesterone, which stimulates growth of uterine lining