Nervous System

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 myelinatedaxons 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