ENDOCRINE SYSTEM

1. ENDOCRINE SYSTEM

2. Mechanisms of Chemical Signaling: a Review Water-Soluble/Nonsteroid Hormones Lipid-Soluble/Steroid Hormones

3. Pathway Example Pathway Example Example Pathway Hypothalamic neurohormone released in response to neural and hormonal signals Low blood glucose Stimulus Stimulus Suckling Stimulus Receptor protein Sensory neuron Sensory neuron Pancreas secretes glucagon ( ) Hypothalamus/ posterior pituitary Hypothalamus Endocrine cell Neurosecretory cell Blood vessel Neurosecretory cell Hypothalamus secretes prolactin- releasing hormone ( ) Posterior pituitary secretes oxytocin ( ) Blood vessel Blood vessel Target effectors Liver Anterior pituitary secretes prolactin ( ) Smooth muscle in breast Target effectors Glycogenbreakdown,glucose releaseinto blood Response Endocrine cell Blood vessel (a) Simple endocrine pathway Milk release Response (b) Simple neurohormone pathway Target effectors Mammary glands Milk production Response Figure 45.2a–c (c) Simple neuroendocrine pathway Control Pathways and Feedback Loops • There are three types of hormonal control pathways

4. One Chemical Signal, Different Effects

5. ENDOCRINE GLANDS • Are ductless and secrete hormones directly into the bloodstream • Target Cells – the cells that a hormone directly affects; if a cell does not have receptors or the receptors don’t respond, the hormone has no effect.

6. Human Endo-crine Glands

7. Most hormones operate by a negative feedback system or feedback inhibition – a stimulus produces a response that opposes the original stimulus; an environmental change “feeds back” to inhibit the original stimulus.

8. The Reproductive Cycle of the Human Female

9. THYROID GLAND • Located in the neck, is the target gland of thyroid-stimulating hormone (TSH) • When the thyroid is stimulated by TSH it releases the hormones Triiodothyronine (T3) and Thyroxine (T4), which regulates the metabolic rate of your body tissues

10. Feedback control loops regulating the secretion of thyroid hormones T3 and T4

11. PARATHYROID GLANDS • These are four pea-shaped organs that rest on the thyroid. They secrete parathyroidhormone which increases blood calcium levels – the opposite effect of what calcitonin does

12. An example of how feedback regulation maintains homeostasis

13. THE PITUITARY GLAND • Often called the “master gland” because it secretes so many hormones (9 total!) • Has two parts: AnteriorPituitary and Posterior Pituitary

14. Remember the acronym: “MAP TO FLAG” to remember the nine pituitary hormones

15. The pituitary sits just below the hypothalamus which regulates the anterior pituitary by secreting neurosecretory hormones that can stimulate or inhibit the actions of it

16. Hormones of the hypothalamus and pituitary glands Nerve cells that release hormones into the blood

17. ANTERIOR PITUITARY • Secretes seven hormones: • Growth Hormone (GH) – stimulates bone and muscle growth • Adrenocorticotropic Hormone (ACTH) stimulates the adrenal cortex to secrete hormones (corticosteroids)

18. ADRENAL CORTEX • ACTH – causes the adrenal cortex to produce its different hormones • Glucocorticoids – target the liver and promote the release of glucose

19. Adrenal Cortex: • Mineralcorticoids – target the kidney and promote the retention of water • Ex: Aldosterone – increases recovery of Na and increases excretion of K and H ions into the urine

20. Thyroid-Stimulating Hormone (TSH) Anterior Pituitary Gland: • Stimulates the thyroid to secrete thyroxine Follicle-Stimulating Hormone (FSH) • Stimulates the follicle to grow in females, oogenesis, and spermatogenesis

21. Anterior Pituitary Gland: Luteinizing Hormone • Causes the release of the ovum during the menstrual cycle in females and testosterone production in males

22. Prolactin Anterior Pituitary Gland: • Stimulates the mammary glands to produce milk

23. Anterior Pituitary Gland Melanocyte-Stimulating Hormone (MSH) : Regulates skin color in lower vertebrates, although its function in humans is unknown

24. Posterior Pituitary Gland: • Secretes Two Hormones: (made by hypothalamus) • Antidiuretic Hormone (ADH) – acts on the kidneys, increasing water retention and thus decreasing urine volume.

25. Oxytocin – is secreted by the stimulation of the nipples during breast feeding and sexual intercourse; it also stimulates uterine contractions during labor Posterior Pituitary Gland

26. ADRENAL GLANDS • Adrenal Medulla – secretes epinephrine (adrenaline) and norepinephrine(noradrenaline)“fight-or-flight” response – increase HR, BP, metabolism, etc

27. Glucose homeostasis maintained by insulin and glucagon

28. THE PANCREAS • Glucagon – stimulates the liver to convert glycogen into glucose and to release that glucose into the blood • Insulin – has the opposite effect of glucagon

29. Major Vertebrate Endocrine Glands and Some of Their Hormones

30. Major Vertebrate Endocrine Glands and Some of Their Hormones (Pancreas–Thymus)

31. What is the advantage of having both a nervous system and an endocrine system? What does the hormone thyroxine affect?

32. What is one effect of an iodine deficient diet? Insulin stimulates cell to remove sugar from the blood while ___________ stimulates the release of glucose from cells.

33. A shortage of dietary iodine makes it impossible for the thyroid gland to produce thyroxine. What would happen to blood levels of thyroxine and the thyroid gland as a result? The role of ADH is to:

34. What is the difference between Type I and Type II diabetes?

35. The thyroid also increases the concentration of calcitonin which decreases the blood’s concentration of calcium.