Understanding the Endocrine System: Glands, Hormones, and Feedback Mechanisms

1. Recap • What is one major function of the Endocrine System? • What is a target cell (or organ)? • Explain how negative feedback works using any of the following examples: • Thirst • Home Heating System • Sweating • Or, your own example

2. The Endocrine System Ch. 9b

3. Glands and Organs of the Endocrine System • Pituitary Gland • Hypothalamus • Thyroid Gland • Parathyroid Gland • Adrenal Gland • Pineal Gland • Thymus Gland • Pancreas • Gonads

4. Exocrine vs. Endocrine Glands • Endocrine Glands • Ductless glands that produce hormones that they release into the blood or lymph • Exocrine Glands • Release their products at the body’s surface or into body cavities through ducts

5. Pituitary Gland • Attached to the Hypothalamus • 2 lobes • Anterior lobe (Made up of glandular tissue) • Posterior lobe (Made up of nervous tissue)

6. Anterior Pituitary Gland • There are 6 hormones released by the anterior pituitary • Growth Hormone (GH) • Responsible for the growth of skeletal muscles and long bones • Stimulates cells to grow and divide • Cause fats to be broken down and used for energy

7. Posterior Pituitary Gland • Doesn’t make hormones, it stores hormones made by the hypothalamus • Oxytocin • Released during childbirth and in nursing women • Causes contractions during childbirth and milk ejection during nursing • Antidiuretic Hormone (ADH) • A chemical that inhibits or prevents urine production • In large amounts, can increase blood pressure

8. Pituitary – Hypothalamus Relationship • The pituitary gland is known as the “Master Endocrine Gland” • Yet, all of pituitary’s glands are controlled by the hypothalamus

9. Thyroid Gland • Located at the base of the throat • Makes two hormones • Thyroid Hormone • Body’s major metabolic hormone • Controls the rate at which glucose is converted into body heat and energy • Calcitonin • Decreases calcium levels in the body by causing it to be deposited in bones

10. Thyroid Gland

11. Parathyroid Gland • Connected to the Thyroid • Makes one hormone • Parathyroid hormone (PTH) • Most important regulator of calcium homeostasis in the blood

12. Quick Quiz 1 of 2 • What gland produces the Growth Hormone (GH)? • Where is the thyroid gland located?

13. Adrenal Glands • Located on the kidneys • Produces 3 major groups of steroid hormones called corticosteroids • When stimulated by the Sympathetic Nervous System (SNS), releases 2 hormones • Epinephrine (adrenaline) • Increases heart rate, blood pressure, blood glucose levels • Norepinephrine

14. Adrenal Glands

15. Pancreas • Located close to the stomach in the abdomen • 2 important hormones • Insulin • Acts on just about all body cells and increases their ability to transport glucose • Absolutely necessary for the use of glucose in the body • Glucagon • Opposite of insulin • Stimulated by low blood sugar levels

16. Pancreas

17. Pineal Gland • Located in the brain • Only secretes one hormone • Melatonin • Levels rise and fall during the course of the day • High levels at night make us drowsy • Low levels during the daylight hours • Important in establishing the body’s day-night cycle

18. Pineal Gland

19. Thymus Gland • Located in the upper thorax (chest) • Decreases in size throughout adulthood • Produces one hormone • Thymosin • Influences immunity in children

20. Gonads • Hormones of the Ovaries • Located in the female pelvis • Produces two groups of steroid hormones • Estrogens • Stimulates the development of the secondary sex characteristics • Helps maintain pregnancy and prepare the breasts for milk • Progesterone

21. Gonads • Hormones of the Testes • Located outside the male pelvis • Produces the male sex hormones • Testosterone • Promotes the growth and maturation of the reproductive system organs • Causes the development of the male’s secondary sex characteristics

22. Quick Quiz 2 of 2 • What hormone is necessary for glucose use in the body? • What is melatonin?