What gets on your “nerves”? I want students to describe a stimulus. I will build a text box with student responses below the question? 4 Vocab: stimulus, a change in the environment that causes an organism to react.

STIMULUS Any change or signal in the environment that can make an organism react. EX: A soccer ball comes zooming toward you. EX: A friend tells you a funny joke. EX: You touch a hot stove.

How do you react? I will build two text boxes: voluntary and involuntary responses. Is it seeing/hearing/feeling the stimulus that causes us to respond like this? Vocab: response

RESPONSE What your body does in reaction to the stimulus. EX: You kick the soccer ball toward the goal. EX: You laugh at the joke. EX: You scream, pull your hand away, hop around, and shake your arm.

VOLUNTARY VS. INVOLUNTARY RESPONSES Body chooses to respond to the stimulus. EX: Choose to kick the ball, choose to not answer the phone when a friend calls. INVOLUNTARY Body automatically responds to the stimulus. EX: heart beats, salivate when something yummy is put in front of you, wrinkle your nose when you smell something stinky.

HOMEOSTASIS The process by which an organisms internal environment is kept stable in spite of changes in the external environment. The nervous system helps maintain homeostasis by directing the body to respond appropriately to the information it receives. EX: When you are hungry, your nervous system directs you to eat. This action maintains homeostasis by supply your body with energy it needs.

I think this is the right place to begin the demo I think this is the right place to begin the demo. The hot sauce demo is a great example of an involuntary response and of the body maintaining homeostasis. We can introduce it after we introduce stimulus and response but it’s a great example to recall when discussing the next couple of slides. Spicy demonstration of homeostasis. Students can volunteer to taste a hot sauce. What is the response to the hot sauce/stimulus?

The Three Functions Of The Nervous System What are the 3 functions of the nervous system? We have seen them or discussed them already.

Receive information 1a receiving information is a function of the nervous system Think of our examples: seeing a bad driver, tasting hot sauce. What do these pictures represent? Our senses. 3a This is how we receive information from outside of our body.

1. RECEIVES INFORMATION Your body checks conditions outside of the body and inside the body. SENSES help monitor changes and keeps the body informed externally.

Nerves also receive information of changes happening internally. 3b We also receive information from inside our body. Think about what happens when your bladder is full or you fill up with gas. That full bladder is a stimulus and we have receptors inside our body that receive that stimulus/ that information and let us know that we need to go the bathroom or burp. We don’t need anything outside of our body to tell us this. Nerves also receive information of changes happening internally.

Respond to information 1b Our nervous system responds to information. Recall student examples of responses. I slow down or speed up to get away from the bad driver. Going to the bathroom, that’s a response. Remember our responses to what gets on our nerves. 5 We had two columns: voluntary and involuntary responses. Remember the response to the hot sauce, it was uncontrollable. 2 All of our responses, voluntary or not, would not be possible without a nervous system. voluntary involuntary

2. RESPOND TO INFORMATION Any change or signal in the environment that can make an organism react to a stimulus. Body (Brain) voluntarily or involuntarily chooses to react to the stimulus.

Maintain homeostasis 1c The last function of the nervous system is maintaining homeostasis. This is almost completely an involuntary response. The spicy hot sauce is a good example. Our body wants to cool our mouth off. Or when our bladder fills up, our body sends a signal to brain saying “find a bathroom, get rid of the soda and maintain homeostasis”. Maintaining our body temp. or our blood pressure are other examples of maintaining homeostasis.

3. MAINTAINING HOMEOSTASIS The nervous system maintains homeostasis by directing the body to respond appropriately to the information it receives. EX: Keeping body temp., glucose levels, and blood pressure regulated.

HOW IS A STIMULUS AND RESPONSE TRASMITTED? NERVE CELLS…NEURONS! A cell that carries information through your nervous system. The message that a neuron carries is called a nerve impulse.

The neuron Dendrites Dendrites axon axon Cell body and nucleus Vocab: neuron, dendrite, axon This is the neuron, the primary cell in the nervous system. 9 the neuron is a cell that carries information through the nervous system. Notice the electricity. The nervous system receives and responds to information. The electricity represents the movement of that message. We call that a nerve impulse. Cell body and nucleus Cell body and nucleus

Dendrites 8 dendrites carry information to the cell body. You can see the dendrites on this nerve cell, they might receive information from any of these senses – directly from your ears or eyes or tongue. The dendrite might receive information from internal receptor to lower or raise your body temp or blood pressure.

DENDRITE Thread-like extensions on a cell body. Carries impulses toward the cell body. Impulse will be transmitted from the dendrite, to the cell body, and down the axon.

axon 7 the axon is an extension from the nerve cell or neuron that carries information away from the cell. 10 This information or message is the nerve impulse. It’s traveling by electricity. It might be a message to … (use student examples of responses, or reactions to spicy demo) or to kick a ball

AXON Carries impulses away from the cell body. All nerves cells have ONE axon. The end of the axon is an AXON TIP. The AXON TIP transmits the piece of information to the next nerve cell. Each neuron can have one or more axon tip.

PATH OF NERVE IMPULSE (STIMULUS/RESPONSE) SENSORY NEURON INTERNEURON MOTOR NEURON

SENSORY NEURON Picks up stimulus from the internal or external environment and converts each stimulus into a nerve impulse. The impulse travels along the sensory neurons until it hits an INTERNEURON. EX: Nerve receptors (dendrites) in ears pick up the sound of the phone ringing. The stimulus is converted to a nerve impulse that travels to the interneuron.

INTERNUERON From the sensory neurons, the nerve impulse passes to interneurons in the brain. The brain interprets the impulses from many interneurons. EX: The interneurons make you realize the phone is ringing. Your brain decided that you should answer the phone.

MOTOR NEURONS The message from the brain travels from the INTERNEURON to the MOTOR NEURON. The motor neurons send the impulses (message) to the muscles to carry out the response. EX: Your muscles walk you to the ringing phone, you pick up the phone, and say “hello?”

Path of a nerve impulse Sensory neuron Motor neuron interneuron Stimulus Vocab: nerve impulse, sensory nerve, interneuron, motor neuron 13aThe sensory neuron senses the stimulus. What are our senses? We have internal sensors to monitor our internal environment. 13b The interneuron carries the impulse from one nerve to another. Here, from a sensory neuron to a motor neuron. Sometimes there might be multiple interneurons. 13d The motor neuron delivers the impulse to the muscle or gland that will respond. Use the student examples of stimuli and responses. These are individual cells. So, how does this impulse travel from one neuron to the next? Let’s look closer at this point where the axon of one nerve meets the dendrites of another nerve. Motor neuron interneuron Response

PATH OF A NERVE IMPULSE

How does the nerve impulse cross the gap between the axon tip and the next neuron? The axon tips release chemicals that enable the impulse to cross the gap at the synapse.

Synapse 14 This is a synapse where the axon of one nerve and dendrites of another meet. At the synapse, the nerve carrying the impulse releases chemicals or chemical messengers that the next nerve picks up at the dendrites. This impulse from stimulus to sensory neuron, across the synapses, the interneuron and the motor neuron travels at 120 m/s or 4.5 miles/hr (speed walking, jogging)

SYNAPSE Space between each axon tip and the next dendrite. Chemical messengers cross this space to pass the message to the next nerve cell.

REACTION TIME The time it takes for a message to travel along your nerve pathways beginning from picking up the stimulus to the delivery of the response