2. The Endocrine System Hormone System

3. What are endocrine hormones? 1.Chemical signals sent from one cell to another target cell. 2.Chemicals for direct cell-to-cell communication. 3.Chemicals that cross a gap between to adjacent cells.

4. Three chemical types used for cell-to-cell communication.

5. Four methods of cell-to-cell communication are found in the human body, ranging from direct to remote communication.

6. Endocrine hormones Produced by endocrine (“ductless”) glands and secreted directly into the bloodstream. Endocrine hormones affect a target cell. Two types: peptides (water soluble; proteins) and steroids (water insoluble; lipids).

7. Hormones and Receptors

8. Non-steroid (or Peptide) Hormones Peptide hormones do not enter the cell directly. These hormones bind to receptor proteins in the cell membrane and release secondary messengers within the cell to alter its activity.

9. (cytoplasm) (nucleus) peptide or amino acid-derived hormone (first messenger) (extracellular fluid) cyclic AMP- synthesizing enzyme cyclic AMP ATP inactive enzyme (second messenger) active enzyme reactant product plasma membrane nuclear envelope receptor The hormone binds to a receptor on the plasma membrane of a target cell 1 The activated enzymes catalyze specific reactions 4 The second messenger activates other enzymes 3 Hormone–receptor binding activates an enzyme that catalyzes the synthesis of a second messenger, such as cyclic AMP 2

10. Steroid Hormones Steroid hormones CAN enter the cell directly through the cell membrane and bind to receptors inside of the target cell to alter its activity. These hormones may directly stimulate transcription of genes to make certain proteins.

11. gene plasma membrane ribosome hormone receptor steroid hormone mRNA (nucleus) RNA polymerase DNA (cytoplasm) new protein (extracellular fluid) A steroid hormone diffuses through the plasma membrane The hormone binds to a receptor in the nucleus or to a receptor in the cytoplasm that carries it into the nucleus The hormone–receptor complex binds to DNA and causes RNA polymerase to bind to a nearby promoter site for a specific gene RNA polymerase catalyzes the transcription of DNA into messenger RNA (mRNA) The mRNA leaves the nucleus, then attaches to a ribosome and directs the synthesis of a specific protein product 1 2 3 4 5 nuclear envelope

12. Role of the Hypothalamus The Hypothalamus monitors the body for temperature, pH and other conditions. Hypothalamus directs the pituitary gland if conditions need to be corrected/altered.

13. Role of the Pituitary Gland The pituitary was formerly known as the “master gland” that signals other glands to produce their hormones when needed. The anterior lobe of the pituitary receives signals directly from the hypothalamus and responds by sending out the appropriate hormone signaling to other endocrine glands. The posterior pituitary receives oxytocin or antidiuretic hormone (ADH) from the hypothalamus, relays them to the body as necessary.

14. hypothalamus pituitary (anterior lobe) capillary bed endocrine cell blood flow blood flow capillary bed pituitary (posterior lobe) Oxytocin and ADH (blue triangles) are secreted into the blood via capillaries in the posterior pituitary Endocrine cells of the anterior pituitary secrete hormones (red squares) in response to releasing hormones; the pituitary hormones enter the bloodstream Neurosecretory cells of the hypothalamus produce oxytocin and ADH Releasing or inhibiting hormones (green circles) are secreted into capillaries feeding the anterior lobe of the pituitary Neurosecretory cells of the hypothalamus produce releasing and inhibiting hormones 1 2 1 2 3

15. Pituitary Hormones Pituitary HormoneFunctions Follicle-stimulating hormone (FSH) Stimulates egg maturation in the ovary and release of sex hormones. Luteinizing hormone (LH) Stimulates maturation of egg and of the corpus luteum surrounding the egg, which affects female sex hormones and the menstrual cycle. Thyroid-stimulating hormone (TSH) Stimulates the thyroid to release thyroxine. Adrenocorticotropic hormone Causes the adrenal gland to release cortisol. Melanocyte-stimulating hormone Stimulates synthesis of skin pigments. Growth hormone (GH)Stimulates growth during infancy and puberty. Antidiuretic hormone (ADH) Signals the kidney to conserve more water. OxytocinAffects childbirth, lactation, and some behaviors.

16. Endocrine Hormones GlandHormonesFunctions ThyroidThyroxineRegulates metabolism CalcitoninInhibits release of calcium from the bones ParathyroidsParathyroid hormoneStimulates the release of calcium from the bones. Islet cells (in the pancreas) InsulinDecreases blood sugar by promoting uptake of glucose by cells. GlucagonIncreases blood sugar by stimulating breakdown of glycogen in the liver. TestesTestosteroneRegulates sperm cell production and secondary sex characteristics. Ovaries Estrogen (in both sexes) Stimulates egg maturation, controls secondary sex characteristics, nurturing and maturation of sperm (in males). ProgesteronePrepares the uterus to receive a fertilized egg. Adrenal cortex Epinephrine (“Adrenaline”) Stimulates “fight or flight” response. Adrenal medulla Glucocorticoids Part of stress response, increase blood glucose levels and decrease immune response. AldosteroneRegulates sodium content in the blood. Testosterone (in both sexes) Adult body form (greater muscle mass), sex drive (in both). Pineal glandMelatoninSleep cycles, reproductive cycles in many mammals.

17. Use the table on the last slide to diagnose the following endocrine issues: 1.A patient who feels cold and listless all the time. 2.A patient who is constantly keyed up and nervous. 3.An elderly patient who is having chronic trouble falling asleep at night. WHATISWRONG?WHATISWRONG?

18. Homeostasis and Hormones Examples of how some hormones help to maintain homeostasis. 1.Thyroid and temperature control 2.Thyroid, Parathyroid and calcium 3.Pancreas and glucose control

19. The thyroid produces thyroxine, which increases metabolism. Thyroid-stimulating hormone is released by the pituitary. The following diagram is illustrating a negative feedback loop that controls body temperature regulation. SOCOLD!SOCOLD!

20. Temperature Control

21. Calcitonin from the thyroid inhibits calcium release from the bones. Parathyroid hormone stimulates release of calcium from the bones. The following diagram illustrates a negative feedback loop that controls blood calcium level. BUTILOVESODA!BUTILOVESODA!

22. Blood Calcium

23. Insulin from the pancreas lowers blood glucose by stimulating body cells to take up glucose. Glucagon from the pancreas increases blood sugar by stimulating the liver to break down glycogen into glucose. The following diagram illustrates the negative feedback loop that controls blood sugar. SOHUNGRY!SOHUNGRY!

24. Blood Sugar Control

25. Other hormone roles… Controlling sleep cycles (melatonin) Controlling reproductive cycles (melatonin, sex hormones) Growth (growth hormone) Responding to stress (epinephrine)

26. Hormones are EVERYWHERE! Many other organs besides the endocrine glands produce hormones. Kidneys produce several hormones that regulate blood pressure, which is essential for kidney function. The digestive system produces several hormones that regulate appetite. Even FAT CELLS secrete hormones called Prostaglandins that MIMIC estrogen!!! :-/