1. + Unit 8: Physiology Control Systems of the Body: The Nervous & Endocrine Systems

2. + Unit 8: Physiology Left SidePgRight SidePg Unit Page48Table of Contents49 Neuron/Synapse50C.N. – Control Systems51 Homeostasis52Section 35-253 Flow Map: I Blood Glucose54Flow Map: Leptin & Humger55

3. + Nervous System Overview Ultimate control of all organ systems. Responsible for communication between parts of the body and interactions with the environment STRUCTURES: brain, spinal cord, & peripheral nerves

4. + Neurons Neurons: nerve cells that carry electrical impulses through the body Impulse = message

5. + TYPES OF NEURONS 1.SENSORY NEURON- receives info from senses (stimuli) 2.INTERNEURON- processes info (in brain & spinal cord) 3.MOTOR NEURON- sends impulse to effector (muscle or gland)

6. + Reflex Arc The impulse travels up sensory neurons, to the spinal cord (interneuron), then immediately travels down motor neurons for a response. The pathway the impulse travels is called the reflex arc

7. + Reflex Arc Receptor (sense organ)  sensory neuron  spinal cord  motor neuron  effector (muscle)

8. + Reflex Arc Sensory Neuron Interneuron Motor Neuron

9. + Structure of a Neuron Axon terminals Myelin sheath Cell body Nodes Axon Dendrites Nucleus

10. + Dendrites Dendrites: receive impulses

11. + Cell body Cell body: contains nucleus & cytoplasm

12. + Myelin Sheath Myelin Sheath: covers the axon; sends the impulse faster

13. + Axon Axon: transmit impulses away from cell body

14. + Nodes Nodes: gaps where impulses jump from one node to the next

15. + Axon terminals Axon terminals: transmits impulse (message) to next cell

16. + Action Potential An impulse begins when a neuron is stimulated by another neuron or by the environment. Gates in the sodium channels open allowing positively charged sodium (Na+) ions to flow into the cell.

17. + This reversal of charges is called the nerve impulse or ACTION POTENTIAL Gates in the potassium channels open, allowing potassium (K+) ions to flow OUT of the cell. This restores the negative potential

18. + The action potential continues to move along the axon in one direction toward the axon terminals. - - - - - - - - - - - - - At Rest 1. + + - - - - - - - - - - Action Potential 2. 3. - - - - + + - - - - - 4. - - - - - - - - - + + -

19. + Synapse Synapse: Synapse: at the end of the axon terminal where a neuron can transfer an impulse to another neuron. Synaptic Cleft The small space between the two neurons is called the Synaptic Cleft Neurotransmitters: Neurotransmitters: chemical signals that transmit an impulse across the synapse to another cell

20. + Homeostasis Homeostasis: The relative maintenance of the body’s internal environment All systems of the body contribute toward maintaining homeostasis The Endocrine System (hormones) works in conjunction with the Nervous System to maintain homeostasis

21. + Endocrine System Overview Maintenance of internal homeostasis ( the internal environment in the body) Regulation of growth and development of an organism. Made up of GLANDS that release hormones into the bloodstream Hormones: chemical "messengers" that control body functions

22. + Major Glands of the Endocrine System

23. + Pituitary Gland Communicates with the hypothalamus to control many body activities (Master Gland) Produces & secretes NINE hormones that affects other glands and organs

24. Hormones of the Pituitary Human Growth Hormone (HGH)- controls growth and height Follicle stimulating Hormone (FSH) / Luteinizing Hormone (LH) – control gonads (development of sperm and eggs/release of sperm and eggs) Thyroid Stimulating Hormone (TSH)- controls the thyroid (metabolism) Adrenocorticotropic Hormone (ACTH)- stimulates growth of the adrenal gland (stress hormones)

25. Pancreas The pancreas produces insulin and glucagon needed for cells to absorb sugar from the blood Insulin – metabolizes sugar Glucagon – maintains blood level of glucose

26. + Negative Feedback Loop Negative Feedback Loop One hormone causes the opposite effect of another hormone. Both are used to maintain homeostasis Examples: Insulin & Glucagon Leptin

27. + Negative Feedback Loop Involving the Pancreas STEP 1: The pancreas releases insulin when there is too much sugar in the blood. STEP 2: Insulin stimulates the liver to remove sugar from the blood and store it as glycogen. STEP 3: When there is not enough sugar in the blood, the pancreas releases glucagon. STEP 4: Glucagon signals the liver to release glucose back into the blood

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29. + Negative Feedback Loop Involving Leptin STEP 1: Fat cells produce leptin when they are filled. STEP 2: Leptin is transported in the blood to the brain where it helps to suppress a person appetite. STEP 3: When the fat is used, the amount of leptin decreases, which causes the brain to start to feel hunger again

30. Individuals without the gene to produce Leptin