* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Leap 2 - Teacher - Teacher Enrichment Initiatives
Central pattern generator wikipedia , lookup
State-dependent memory wikipedia , lookup
Types of artificial neural networks wikipedia , lookup
Neuroeconomics wikipedia , lookup
Action potential wikipedia , lookup
Apical dendrite wikipedia , lookup
Embodied cognitive science wikipedia , lookup
Aging brain wikipedia , lookup
Multielectrode array wikipedia , lookup
Microneurography wikipedia , lookup
Neuroregeneration wikipedia , lookup
Endocannabinoid system wikipedia , lookup
Activity-dependent plasticity wikipedia , lookup
Metastability in the brain wikipedia , lookup
Axon guidance wikipedia , lookup
Neural oscillation wikipedia , lookup
Premovement neuronal activity wikipedia , lookup
Caridoid escape reaction wikipedia , lookup
Mirror neuron wikipedia , lookup
Optogenetics wikipedia , lookup
Sparse distributed memory wikipedia , lookup
Neuromuscular junction wikipedia , lookup
Clinical neurochemistry wikipedia , lookup
Electrophysiology wikipedia , lookup
Development of the nervous system wikipedia , lookup
Channelrhodopsin wikipedia , lookup
End-plate potential wikipedia , lookup
Neural coding wikipedia , lookup
Holonomic brain theory wikipedia , lookup
Feature detection (nervous system) wikipedia , lookup
Pre-Bötzinger complex wikipedia , lookup
Synaptogenesis wikipedia , lookup
Nonsynaptic plasticity wikipedia , lookup
Neuroanatomy wikipedia , lookup
Single-unit recording wikipedia , lookup
Chemical synapse wikipedia , lookup
Molecular neuroscience wikipedia , lookup
Synaptic gating wikipedia , lookup
Biological neuron model wikipedia , lookup
Nervous system network models wikipedia , lookup
Stimulus (physiology) wikipedia , lookup
Making the leap part 2 observing Transmission of information through neurons Teacher pages Activity description: After making observations and inferences in Making the Leap Part 1, students will rotate through six stations, each with Station Cards that explain how nerve impulses are transmitted through neurons. In this way, information is automatically chunked into small batches for students. Using the six station cards and a Neuron Graphic Organizer, students will utilize multiple learning styles to describe, illustrate, explain, and make analogies as they construct understanding about the electrochemical process of conducting information through neurons. Activity Background: The nervous system is like an electrical network that relays information to and from the brain and spinal cord, allowing communication among all body systems and the brain. Sensory information, such as temperature, touch, vision, taste, and sound is received by the nervous system. It is relayed through neural networks to the brain or spinal cord, which make up the central nervous system (CNS). In the CNS, information is interpreted. Messages are sent from the CNS through specific nerve pathways so the appropriate body part or system responds. dendriTes nuCleus There are millions of nerve cells (neurons) in the body. They form Axon complex nerve pathways Axon Tip between the CNS and other body systems. Neurons are especially designed to transmit nerve impulses. Neurons have extensions off of the Cell Body cell body called dendrites and axons (Figure 1). Figure 1 neuron Positively Aging®/CAINE 2009© The University of Texas Health Science Center at San Antonio ConTenT lesson neurotransmission: Content lessons Using a Neuron Graphic Organizer, station cards, and images provided in this lesson, students will be able to: n Explain how neurons transmit signals via an electrochemical process n Compare and contrast their observations and inferences from Making the Leap Part 1 with information provided in this activity Activity overview Activity objectives: 1 When a stimulus begins the transmission of information, an impulse travels through a single neuron first as an electrical impulse. How does this electrical impulse happen? The stimulus changes the balance of charged particles in the neurons relative to body tissues around the neurons. eleCTriCAl energy in A neuron Important elements and compounds in neurons are sodium, potassium, calcium, chloride, and some proteins. All of these chemicals can exist as charged particles called ions. Ions can have either a positive or negative charge depending upon the numbers of protons and electrons. If there are more protons than electrons, the charge will be positive. If there are more electrons than protons, the charge will be negative. Unbalanced positive and negative charges within neurons cause an impulse to travel through the neuron. Table 1 Important Ions in the Nervous System Ion sodium potassium Calcium Chloride protein Charge +1 +1 +2 -1 + or – Charges possible Numbers of Extra Protons or Electrons 1 more proton than electrons 1 more proton than electrons 2 more protons than electrons 1 more electron than protons How do the charged ions make the electrical impulses travel through neurons? Neurons at rest have more negatively charged proteins and chloride inside them than positively charged particles. This means, at rest, a neuron has a slightly negative charge as compared to the charge outside of the cell (Figure 2). iMpulse in neuron ACTion poTenTiAl node oF rAnvier ++ ++ +++ ++ Myelin sheATh Cell Body (soMA) Figure 2 negative Charge in neuron Positively Aging®/CAINE 2009© The University of Texas Health Science Center at San Antonio ++ ++ ConTenT lesson neurotransmission: Content lessons How do the impulses begin their journey through the neuron? It all starts with a stimulus. A stimulus is anything that causes a reaction. A stimulus can be external, when it occurs outside the body (such as a temperature change or hitting your arm), or it can be internal, (such as feeling thirsty when the body needs water). Activity overview, continued Dendrites receive impulses and carry them to the cell body. Axons carry information away from the cell body. “Information” in the nervous system travels through neurons as electrical impulses. 2 If the overall charge of a neuron becomes positive enough to fire off an impulse, it will travel from its point of origin and ultimately through the axon. As the impulse travels, it causes a burst of positively charged activity. As the impulse travels along the axon, it comes to the end of the neuron, also known as the axon tip or terminal. There is not a direct connection between the axon tip of one neuron and the dendrite of another neuron. Surprisingly, a gap (synapse) exists (Figure 3). The impulse is in an electrical form when it reaches the synapse and cannot cross in that form. What happens to the electrical impulse? How can it “leap” across the gap between one neuron and the next? This is where the chemical portion of “electrochemical” comes into it. Sending Cell Vesicle Transporter Synapse Receptor Molecules Neurotransmitter Receiving Cell Figure 3 synapse (Adapted from http://www.drugabuse.gov/NIDA_notes/NNvol21N4/Impacts.html) Chemical Energy in the Neuron: We have all seen energy transformations when chemical energy is transformed to electrical, then radiant and thermal energy in a battery powered flashlight. In a neuron, a similar energy transformation takes place, except the electrical energy is transformed to chemical energy at the end of axons (axon terminal). When the electrical impulse reaches the axon terminal, it causes a special chemical (neurotransmitter) to be released. The neurotransmitter crosses the synapse, in a chemical form, to the dendrites of the next neuron. This starts the electrical impulse in the next neuron. Positively Aging®/CAINE 2009© The University of Texas Health Science Center at San Antonio ConTenT lesson neurotransmission: Content lessons If enough sodium ions move in, an impulse will be sent. If not, no impulse will be sent. It is an “all or none” event. Eventually, potassium ions will move out of the neuron and sodium stops moving into the cell. This causes the neuron to return to its negatively charged resting state. Neurons expend energy to move sodium and potassium in and out of the cell. Activity overview, continued When a stimulus occurs, it causes a change in the arrangement of the potassium (+1) and sodium (+1) ions in and around the neurons. Sodium (+1) ions will begin to move into the neuron. The overall charge of the neuron begins to change. Sodium ions have a positive charge, so the neuron becomes less negative as sodium ions move inside. 3 The chemical neurotransmitter is no longer needed; it served only to prompt an electrical signal to travel through the receiving neuron. Four things can happen to the leftover neurotransmitter as the impulse continues its journey in electrical form. The neurotransmitter can: 1. diffuse or drift out of the cell 2. be destroyed by chemical reactions that take place in the “receiving” neuron 3. be destroyed by specialized “clean up” glial cells 4. be reabsorbed back into the “sending” neuron - this reabsorption will signal cells to STOP releasing additional neurotransmitter, until the next stimulus occurs. This signaling to STOP releasing additional neurotransmitter is an example of a negative feedback loop. In a negative feedback loop, an action will continue until something tells it to stop. The thermostat on an air conditioner works this way. When the temperature becomes too warm, the air conditioner will start to run. When the thermostat senses that the temperature has become cooler, it will relay that information to the air conditioner and the air conditioner will stop making cold air. Neurotransmitters: There are at least 100 different neurotransmitters, and they have different functions. The neurotransmitters are synthesized from the proteins in the food we eat. Table 1 lists common neurotransmitters and their functions within the body. When the body receives a stimulus, the area of the brain that processes the stimulus and the resulting response determines which of the neurotransmitters will be activated. Positively Aging®/CAINE 2009© The University of Texas Health Science Center at San Antonio ConTenT lesson neurotransmission: Content lessons Remember, neurons are like wires. Similar to the chemicals in a battery in a flashlight, the chemical itself does not travel along the network or “wires”, only the impulse does. What happens to the special chemical neurotransmitter once it has reached the next neuron? Activity overview, continued Neurotransmitters are stored as molecules in storage areas called vesicles in the axon terminals of the “sending” neuron. They wait for an electrical impulse to come. If the impulse is strong enough, it acts as a signal for the neurotransmitter to leave the vesicle and cross the synapse to the dendrites of the next neuron, or the “receiving” neuron. The neurotransmitter will diffuse out of the axon tip or terminal, and be “accepted” by specialized receptor areas on the dendrite of the next neuron. The receptors are specialized, so they receive only their “own” neurotransmitter. As the neurotransmitter is received by the receptor, it triggers electrical impulses which travel through the neuron to the axon tip at the next synapse and the process repeats through a network of neurons until the information reaches its destination. 4 Table 1: Common neurotransmitters and Their Functions Neurotransmitter Function We’ve learned that different areas of the brain control intelligence, emotions, feelings, memory, and physiological functions. The neurotransmitters in the brain facilitate these functions. No stimulus or response can happen in the nervous system without the neurotransmitters. The neurotransmitters can either cause an effect or feeling (excitatory) or prevent an effect or feeling (inhibitory). These chemical compounds exist in a delicate balance (equilibrium). The type of neurotransmitter activated, either inhibitory or excitatory, is dependent on the activity and the part of the brain involved. Physical activity, for example, causes release of neurotransmitters called endorphins. Endorphin release triggers feelings of well being. That is why an individual generally feels good after exercise. Also, endorphin release will mask feelings of pain. Endorphin release in long distance runners masks the discomfort associated with extreme physical activity, so they are able to keep going. Feelings of depression are closely related to neurotransmitters, such as serotonin. Serotonin is often reabsorbed back into the sending neuron after it has relayed the electrical information to the receiving neuron. Sometimes, too much serotonin is reabsorbed, and not enough remains in the synapse. This can cause feelings of depression. Commonly prescribed antidepressants such as Prozac prevent the “reuptake” of serotonin back into the sending neuron. This allows more to remain in the synapse and relieving feelings of depression. Such antidepressants are known as “Selective Serotonin Reuptake Inhibitors” or SSRIs. Positively Aging®/CAINE 2009© The University of Texas Health Science Center at San Antonio ConTenT lesson neurotransmission: Content lessons Fight or flight Long term memory, hunger, sleep/ wake cycle dopamine Pleasure / reward system, movement, attention, memory serotonin Emotions, sleep, satiety Acetylcholine Thirst, body temp, short term memory, motor function glutamate Neuron activity (increases it), learning / cognition memory endorphins Emotion, pain, pleasure, appetite. Released with exercise gABA (gamma-aminobuyricacid) Neuron activity (slowed), anxiety, memory, anesthesia Activity overview, continued Adrenalin (epinephrine) norepinephrine (noradrenalin) 5 5 sets of Making the Leap Station Cards Colored pencils 1 Copy Processing Out Section per student Activity instructions: • • • • • • • Set up six stations so there are five copies of the same Making the Leap Station Cards at each station. Divide class into six groups. Assign each group to a station. Instruct students to read the station card carefully and to look at the illustrations on the card. They should re-read the card and then discuss it in their group. Individually, students should work on their Making the Leap Flow Chart, filling in information and diagrams as instructed on the flow chart. When most students have completed the station, ask students to rotate to the next station. Repeat until all stations have been completed. Cut out the dice at the end of the activity and use for review. Management suggestions: Laminate the Making the Leap Station Cards for durability and reuse. Be sure to circulate among the stations to help direct discussion and answer questions about the flow chart. suggested Modifications: Visit students needing assistance more frequently as you circulate through the stations. You might also provide a flow chart that is partially filled to help these students complete their task and to ensure they have correct information at the end of the activity. suggested extensions: Students develop “claymation” videos showing process of impulse traveling through the nervous system. Examples can be found on the Internet to give students an idea of what these might look like. This idea might also be used instead of the stations for high ability students needing enrichment. Positively Aging®/CAINE 2009© The University of Texas Health Science Center at San Antonio ConTenT lesson neurotransmission: Content lessons Materials: Activity overview, continued Many different substances and activities can affect the function of neurotransmitters. Some of these include: emotions, physical activity, genetic makeup, illness, foods consumed, starvation, pain, injury, drugs, and chemicals in our environment. Remember, all bodily functions and activities require neurotransmitters. A well-functioning, healthy body requires the release and synthesis of neurotransmitters. This release and synthesis must occur in such a way as to maintain optimum balance. 6 references used: Merck manual of diagnosis and therapy - 18th ed. (2006). Section 16 Neurologic disorders and neurotransmission, p 207. Nervous System. (2009). In Compton’s by Britannica. Retrieved June 29, 2009, from Encyclopædia Britannica Online School Edition: http://school.eb.com/comptons/article-205350 Walker, Richard; Parker, Steve; and Winston, Robert. (2007). The Human Body (Book & DVD). DK Publishing, Inc., 256 pp. Positively Aging®/CAINE 2009© The University of Texas Health Science Center at San Antonio ConTenT lesson neurotransmission: Content lessons National Institutes of Health Medline Plus Website accessed from http://www.nlm.nih.gov/medlineplus/ on July 29, 2009 Activity overview, continued National Institute on Drug Abuse (NIDA) for Teens. Retrieved June 20, 2009 from http://teens.drugabuse.gov/blog/tag/neurons/ 7