1. Nervous System

2. Meet Your Nervous System You have about 150 billion brain cells Your brain is about 2% of your body’s weight, but it uses about 20% of your energy. Left half of brain controls right side of body, and vice versa Longest cell in the body = neuron (sciatic nerve cell) that goes from spine to foot; about 3 feet long

3. What are the functions of the nervous system? 1. Send sensory information (touch, sight, smell, taste and sound) from the body to the brain 2. Send commands from the brain to the body 3. Balance and Coordination 4. Reflexes and Instincts 5. Thinking and speech 6. Memory 7. Emotions 8. Dreams …and more!!

4. What are the 2 parts of the nervous system? 1. Central Nervous System (CNS) = the brain and the spinal cord 2. Peripheral Nervous System (PNS) = all the nerves in the rest of your body

5. Classify: Label each of the following as central nervous system or peripheral nervous system: 1.A group of nerve cells in the brain that store a memory 2.A nerve cell in the skin that feels pain when you burn your finger 3.A group of brain cells that control body temperature 4.A nerve in your leg that makes a leg muscle move when you run 5.A nerve cell in your spinal cord that connects the brain to a muscle cell

6. Higher level thinking, memories, emotions Voluntary movements, balance, posture, and speech Connects brain to spinal cord and controls involuntary processes, like breathing

7. What is a neuron? -a nerve cell (synapse: gap between neurons)

8. What are the 3 types of neurons? 1. Sensory Neurons: receive sensory information (stimuli of touches, sounds, looks, tastes, or smells) and sends the information to CNS 2. Motor Neurons: carry commands from CNS to muscles and other cells in the body. 3. Interneurons: connect sensory neurons and motors neurons in the central nervous system

9. How do neurons transmit impulses (send message to other cells)?

10. How neurotransmitters work :

11. What is a neurotransmitter? A tiny molecule that carries a message across a synapse. Released from the axon of one neuron, into the dendrite of another neuron.

12. How do neurons transmit impulses (send message to other cells)? 1. The dendrites receive a signal from another neuron 2. An electrical impulse travels very quickly down the axon 3. When the electricity reaches the end of the axon, neurotransmitters are released across the synapse. 4. The neurotransmitters travel to the dendrites of the next neuron, and trigger a new electrical impulse in that neuron.

13. What is a reflex arc? 1) A sensory neuron sends a signal that part of your body is in immediate danger. 2) The impulse reaches your spinal cord. 3) The spinal cord sends a command (without going to the brain) through motor neurons that makes you react quickly

14. Sum It Up 1. What are the parts of the CNS? 2. What are 4 functions of the nervous system? 1. Why do we need neurotransmitters?