The Nervous System

1. The Nervous System A Brief Overview!

2. What you will understand at the end of this lecture: • Functions of the nervous system • Divisions of the nervous system • Parts of the nervous system • Nerve cell (neuron) structure • How a message travels throughout your body

3. Nervous System Functions • Communication! • Receive info • Process info • Respond to info • Maintain homeostasis • Homeostasis: the process of maintaining the balance inside your body, regardless of your external environment (ex. Maintaining a normal temperature)

4. Thinking Feeling Moving Tasting Seeing Hearing Talking Smelling Touching Nervous System Functions

5. Function #1: Receiving Info • Nervous System receives info from INSIDE and OUTSIDE your body • Helps you be AWARE of your surroundings • Keeps internal body conditions in check (normal) ex. Blood sugar level, heart rate, temperature

6. Function #2: Responding to Info • STIMULUS: signal that triggers nervous system to react • Ex. Mosquito buzzing, phone ringing, ball flying toward your face • NS responds to stimulus • RESPONSE: what your nervous system tells your body to do to react to the stimulus • Ex. You hit mosquito, you answer phone, you catch the ball

7. Central Nervous System Peripheral Nervous System Divisions of the Nervous System http://www.thepharmamarketing.com/imgposter/CH5183.jpg

8. Brain and spinal cord Brain: controls body’s functions Spinal cord: connects brain to nerves of peripheral nervous system to relay messages Central Nervous System

9. Somatic Nervous System Controls VOLUTARY actions Autonomic Nervous system Controls tasks you do not think about Breathing, heart rate, body temp. Divided into sympathetic and parasympathetic systems Peripheral Nervous System Divided into Somatic and Autonomic Nervous system

10. Peripheral Nervous System http://www.montana.edu/wwwai/imsd/rezmeth/anatomy.htm

11. Peripheral Nervous System Calm- ing Energy Conser-vation Fight or flight http://www.drstandley.com/images/nervous5.bmp

12. Nervous System Organization http://homepage.psy.utexas.edu/homepage/class/Psy301/Salinas/sec2/Brain/transparencies03.html

13. Organization • Cells --> tissues --> organs --> organ systems • Nerve cell --> nerves --> brain --> central nervous system (brain and spinal cord) • Nerve - bundle of nerve cells held together by connective tissue

14. Neuron Structure • Specifically designed to carry messages • Main parts: Dendrites, cell body, axon, axon tip

15. Neuron Structure • Dendrites: receives incoming stimulus, sends message to cell body • Cell body: contains organelles, passes message to axon • Axon: carries message (impulse) awas from the cell body towards the next neuron’s dendrites • Axon tip: end of axon, message reaches here and jumps to next neuron’s dendrites

16. Neuron to Neuron: Passing the message along http://www.ascd.org/ASCD/images/publications/books/sprenger1999_fig1.2.gif

17. Neuron to Neuron: Passing the message along http://psych.hanover.edu/krantz/neurotut.html

18. Neuron Types • Sensory neuron: senses stimulus, changes it into an impulse • Interneuron: passes impulse from neuron to neuron • Motor neuron: sends impulse to muscle or gland or part of body that needs to respond to stimulus

20. Neurons (SEM picture)

21. Nerve Impulse (Message) • Travels from dendrites --> cell body --> axon --> axon tips --> jumps synapse (space between 2 neurons) --> dendrites --> cell body --> axon --> axon tips • Impulses can travel 120 m/s • Impulses travel across synapse either as an electrical signal or a chemical signal