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NERVOUS SYSTEM The excitable highway. Brainstorm  Groups of 3-4  On Chart Paper, make a mind map of what you know of the nervous system  Thoughts,

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Presentation on theme: "NERVOUS SYSTEM The excitable highway. Brainstorm  Groups of 3-4  On Chart Paper, make a mind map of what you know of the nervous system  Thoughts,"— Presentation transcript:

1 NERVOUS SYSTEM The excitable highway

2 Brainstorm  Groups of 3-4  On Chart Paper, make a mind map of what you know of the nervous system  Thoughts, ideas, knowledge

3 Gallery Walk  Take about 3-4 Minutes to look around at other groups Mind Maps  Bring your group’s marker to add any thoughts or ideas  What do these mind maps look like?

4 Learning Goals  Learn the components of a neuron  Differentiate amongst the three different types of neurons

5 Nerve Cell (Neuron)  Dendrite: Receivers  Cell Body: Houses the nucleus and the majority of the organelles of the cell  Nucleus: Brain of the cell Nodes of Ranvier

6 Nerve Cell (Neuron)  Axon: Conducts the nerve impulse along the cell  Myelin Sheath: Some neurons are covered in a fatty myelin sheath  Axon Terminals: relay messages to other neurons  Nodes of Ranvier: Gaps where there is no myelin covering

7 Nerve Highway  Neurons are the primary component of the nervous system  Nervous system includes the brain, spinal cord and peripheral ganglia  Neurons can be divided into different specialized neurons: Sensory, Motor and Interneurons

8 Different types of Neurons  Split into 3 different groups  Using Chart Paper, describe your group’s designated neuron  Designate a few members to present findings to the class

9 Sensory Neuron  Convert external stimulus into an internal stimulus  Stimulated by sensory input (touch, sound, smell, temperature) and send information to the brain  Unlike neurons from the central nervous system, which are activated by other neurons, sensory neurons are activated by a physical sensory input

10 Motor Neuron  Composed of neurons within the CNS, and extend axons out of the CNS, to control muscular contractions  Somatic Motor Neurons: Control skeletal muscular contractions  Visceral Motor Neurons: Innervate cardiac and smooth muscle

11 Interneurons  All neurons within the CNS are composed of interneurons  Local connections within specific neurons  Form chain networks and “highways”

12 Recap  Neuron/Nerve Cell Structure  Sensory Neuron  Motor Neuron  Interneuron

13 Learning Goals  Understand the concept of an Action Potential  Look at the importance of the Sodium-Potassium Pump

14 How do Neurons transmit a nerve impulse  Nerve Impulse: a message that is sent or convey information along a neuron  Measured using oscilloscope (voltage expressed in millivolts mV – measure of the electrical potential difference between two points)

15 Resting Potential  Voltmeter is attached along the axon of a neuron, we can monitor the difference in voltage  -65 mV

16 Threshold  Sodium pumps begin to open, changing the flux in gradient

17 Action Potential - Depolarization  Rapid change in polarity across the membrane  All or none principle  Sodium Gates Open  + 40 mV

18 Action Potential – Repolarization  Potassium gates open and potassium flows down the concentration gradient  -70mV

19 Refractory Period  After the depolarization period, the axon undergoes a “limbo” period, where the Sodium gates cannot open  This ensures the AP can only move towards the axon terminal  -65 mV

20 DEMO  PHET Neuron

21 Speed of Transmission  In Myelinated axons, gated Sodium-Potassium pumps are concentrated at the Nodes of Ranvier  The action potential skips from node to node, creating a faster action potential  Therefore AP’s travel faster on myelinated axons that non-myelinated axons

22 Recap  Nerve Impulse  Resting Period  Action Potential  Depolarization  Repolarization  Refractory Period  Speed of Transmission

23 Draw an Action Potential Graph  Graph out a Nerve Impulse  Include, stages of an action potential charges, extra/intracellular sodium and potassium levels, Na, K gates,

24 Recap

25 How do Neurons transmit messages  Recall that axons end in branched axon terminals.  Axon terminals are within close proximity to dendrites of other neurons  No physical contact, separated by a gap called the synaptic cleft (synapse)

26 Learning Goals  How do neurons send messages amongst each other  Learn a few of the primary neurotransmitters

27 Synapse – Relayed Message  Occurs when an AP reaches the axon terminal  Triggers the influx of Sodium to the terminal  Stimulates vesicles filled with Neurotransmitter to fuse with the synaptic membrane to release the neurotransmitter  Neurotransmitter cross the synaptic cleft and bind to receptors proteins on the post synaptic membrane to trigger Sodium gates to open, causing an action potential to begin

28 Reuptake  Neurotransmitter is either reabsorbed by the presynaptic neuron OR  Broken down by specific enzymes  Acetylcholine > acetylcholinerase

29 Neurotransmitter  Chemicals that transmit signals from a neuron to a target cell across the synapse  Depending on the neurotransmitter, can cause a excitatory or inhibitory response  Acetylcholine (ACh) – responsible for muscular contractions at the neuromuscular junction  GABA – primary inhibitory transmitter in the brain

30 Neurotransmitter Project  STSE – Society, Technology, Science, Environment  Form groups of 2 people  Sign up for a topic on things that may effect neurotransmitters or disorders of the brain  Create a 5-7 minute presentation on your specific topic – Can be a powerpoint, skit, demo, etc…  Include a 1 page (double spaced) write up of your findings – APA format referencing  Presentations on Monday!

31 Example  GOOGLE “MOUSE PARTY” – interactive demo

32 iPad work Period  Use iPad’s to work on project!

33 Learning Goals  Learn the components of the Central Nervous System (CNS)  Understand the functions of the CNS

34 Central Nervous System  Composed of the brain and spinal cord  Sensory information is received, motor initiation begins  Protected by bone – skull and vertebrae  Also cushioned by Cerebrospinal fluid

35 Central Nervous System  Brain contains interconnecting cavities called ventricles, which connect to the central canal of the spinal cord.

36 Spinal Cord  Spinal cord is protected by individual vertebrae  Vertebrae are separated by intervertebral discs

37 Spinal Cord  Grey matter contains sensory neurons, motor neurons and interneurons. Dorsal Root of the spinal nerve contains sensory fibers entering grey matter  Ventral Root contains motor fibers exiting the grey matter  Join before leaving the vertebral column

38 Spinal Cord  White matter contains tracts of neurons taking information to or from the brain  Dorsally: Ascending tract to the brain  Ventrally: Descending tract away from the brain

39 The Brain  The brain is composed of: cerebrum, diencephalon, cerebellum, brain stem  Divided into 2 hemispheres  Each hemisphere is composed of the frontal lobe, parietal lobe, occipital lobe, and temporal lobe

40 The lobes  Frontal Lobe: Higher order processes, executive functions and movement  Parietal Lobe: integrating sensory information  Occipital Lobe: Visual processing centers  Temporal Lobe: Auditory perception

41 The Brain  Gallery Activity -  Cerebrum  Cerebellum  Medulla Oblongata


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