1. I. Regulatory Systems Both the Nervous System and the Endocrine System are responsible for cellular communication within an animal, and maintaining homeostasis. A. The Endocrine System is slower and involves the production of hormones

2. What are Hormones? B. Hormones are chemical signals (proteins) that communicate within an animal C. Hormones are secreted from the endocrine cell into the blood stream where they are carried to other tissues (target cell.)

3. What are Glands What are Glands D. A gland is a organ that releases hormones. E. Specific hormones affect specific target cells

4. The Pancreas F. The Pancreas is a gland that secretes digestive enzymes as well as hormones. G. The pancrease releases 1. Insulin 2. Glucagon

5. H. The Pancrese is filled with blood vessels, allowing the insulin to directly enter the bloodstream

6. Insulin I. Insulin is a hormone that is secreted in response to high blood glucose levels. J. A normal adult blood glucose level is 90mg/100ml

7. Glucagon K. However, when blood sugar gets too low an opposing hormone glucagon is released from the pancreas to put back glucose (which is stored in the liver) back into the blood

8. The Nervous System: A. The Nervous System uses high speed messages.

9. The Nervous System: B. The basic unit is the NEURON C. A neuron is a specialized nerve cell which transmits information to and from the brain

10. Chemicals: D. Neurotransmitters – chemicals which carry the electrical messages from one neuron to the next transmitting the signal.

11. Neurotransmitters

13. Parts of the Neuron: E. Dendrites – pick up sensory information and are elaborately branched F. Axon – transmits electrical impulses from the dendrites to the terminal branches G. Myelin Sheath – protects and insulates the axon, and focuses the impulse

14. Reflex Arc – 1. A tap on the knee stimulates sensory receptors, generating a nerve signal. 2. The signal travels along a nerve pathway to the spinal cord. 3. At the spinal cord, the signal is transmitted from the sensory nerve to a motor nerve. 4. The motor nerve sends the signal back to a muscle in the thigh. 5. The muscle contracts, causing the lower leg to jerk upward. The entire reflex occurs without involving the brain.