1. Chapter 39 Endocrine System Section 39-1

2. Endocrine System Function: To communicate and coordinate body systems with chemical messengers delivered through the bloodstream. Chemical messengers: HORMONES Regulated by: Negative feedback loops Endocrine Organs: Hypothalamus, pituitary gland, pancreas, ovary, testes, thyroid, parathyroid, and adrenal gland.

3. Endocrine Glands of the Human Body

4. Hormones are specific! Hormones only attach to their target cell. Target cells have unique receptors for specific hormones Ex: estrogen only attach to estrogen receptors, insulin cannot attach to estrogen receptors.

5. Comparing Nervous and Endocrine Systems NervousEndocrine CellsNeurons Endocrine cells Chemical Signal NeurotransmitterHormone Speed of onsetSeconds Seconds to hours Duration of action Very brief unless neuron activity continues Brief or may last for days

6. Neurons connect directly to target cells. Endocrine cells release hormones into bloodstream to reach target cells.

7. Pancreas releases insulin into the blood Body cells absorb glucose Blood glucose level decreases Normal blood glucose level Blood glucose level decreases Pancreas releases glucagon into blood Liver converts glycogen to glucose Blood glucose level increases Liver converts glucose to glycogen Blood Sugar Feedback Loop Section 39-2 Sugar = glucose What is the control center? What are the effectors?