The nervous system

1. The nervous system

2. Nervous and endocrine systems The nervous and endocrine glands systems interact to control and coordinate the body’s -responses to change in its environment -growth & development -reproduction

3. A. Nervous system: Nervous control depends mainly on the functioning of neurons (nerve cells).

4. 1. Stimulus: a change in the external or internal environment which initiates and impulse. examples: vision, smell, taste, pressure, temperature, pain, equilibrium. • A demonstration

5. 2. Impulse: an electro-chemical charge generated along a neuron. • Electro-inside neuron • Chemical: between neurons http://en.wikipedia.org/wiki/Action_potential http://ffden-2.phys.uaf.edu/212_fall2003.web.dir/Casey_Adamson/Personal%20Web%20Page.htm

6. 3. Receptors: structures specialized to detect certain stimuli 4. Response: a reaction to a stimulus http://meredithbond.com/blog/stimulus-and-response/

7. 5. Neuron: the basic cellular unit of the nervous system (specially designed for the transmission of impulses.) Our brain has millions of neurons.

8. Neuron

9. Neuron a. Terminal branches: ends of axons that secrete neurotransmitters. b. Synapse: gap between adjacent neurons (terminal branches of one neuron and the dendrites of the next) or the gap between neuron and effector.

10. 6. neurotransmitter • Neurotransmitter: chemical substance which starts the transmission of the nervous impulse (Acetylcholine degraded by cholinesterase)

11. Neurotransmitter con’t • Acetylcholine is the most common neurotransmitter. • Dopamine is another neurotransmitter that brings pleasure. http://www.muscular-dystrophy.org/research/news/3262_study_compares_two_treatments_for_myasthenia_gravis

12. Why do you think the nervous system is important?

13. How do neurotransmitters work to transmit the nervous impulse in humans? 1. Nervous impulse travels down an axon to the tips of a terminal branch. 2. The terminal branch secretes neurotransmitter into the synapse gap. 3. The neurotransmitter travels to the next neuron and causes depolarization of that neuron-thus a new nervous impulse is started in the next neuron.

14. video Synapse Structure and Function • http://www.youtube.com/watch?v=rWrnz-CiM7A

15. Neurons may release chemicals to stimulate each other. An example of a muscle being stimulated by a neuron appears after the reflex path pictured in number four in the diagram.

16. More complex animals have a central nervous system which includes a brain and a nerve cord (spinal cord). • Brain: a large mass of neurons located in the cranial cavity—contains three major divisions.

17. Cerebrum: center for voluntary activity; interprets sensory impulses, initiates some motor activities, and responsible for memory, thinking, and reasoning.

18. Cerebellum: coordinates motor activities and aids in maintaining balance. • Medulla: controls involuntary activities such as breathing, heartbeat, blood pressure and peristalsis ( is part of the brain stem),

19. Video The nervous system http://www.youtube.com/watch?v=sjyI4CmBOA0

20. Spinal cord: lies within, and is protected by, the vertebrae of the spinal column. http://www.quantumday.com/2012/06/walking-again-after-spinal-cord-injury.html

21. -- is continuous with the brain coordinates activities between the brain and other body structures (bridge between the brain and the peripheral nervous system) -- it is also a center for reflex actions.

22. Peripheral nervous system -- is located outside the central nervous system and consists of the nerves extending throughout the body. http://www.umm.edu/imagepages/8679.htm

23. Peripheral nervous system • somatic: voluntary control • automatic: involuntary