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Nerves, Hormones, & Homeostasis

Nerves, Hormones, & Homeostasis. http://ehumanbiofield.wikispaces.com/Neuron+Structure+NLL. http://www.youtube.com/watch?v=xRkPNwqm0mM. http://www.youtube.com/watch?v=lh4pdaWYu7A. http://www.biologyreference.com/Oc-Ph/Peripheral-Nervous-System.html. http://i-biology.net/.

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Nerves, Hormones, & Homeostasis

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  1. Nerves, Hormones, & Homeostasis http://ehumanbiofield.wikispaces.com/Neuron+Structure+NLL

  2. http://www.youtube.com/watch?v=xRkPNwqm0mM http://www.youtube.com/watch?v=lh4pdaWYu7A http://www.biologyreference.com/Oc-Ph/Peripheral-Nervous-System.html

  3. http://i-biology.net/

  4. http://i-biology.net/

  5. The Reflex Arc

  6. The reflex arc – nerve impulse conduction Receptor to CNS: Sensory neuron Within CNS: Relay neuron CNS to effector: Motor neuron http://i-biology.net/ http://msjensen.cehd.umn.edu/1135/links/animations/flash/0016-swf_reflex_arc.swf

  7. Nerve impulses are conducted along the neuron The nerve impulse results from a change in concentrations of sodium (Na+) & potassium (K+) ions across the membranes of a neuron. These changes are called depolarization and repolarizations Resting potential: the electrical potential across the membrane of a cell that is not conducting an impulse Action potential: the reversal (depolarization) & restoration (repolarization) of the electrical potential across the plasma membrane as a nerve impulse passes along a neuron.

  8. The Action Potential http://www.youtube.com/watch?v=ifD1YG07fB8

  9. Resting Potential: Is the electrical potential across the plasma membrane of a cell that is not conducting an impulse Resting potential is maintained by Active transport Some potassium ions diffuse back out, leaving the outside more positive and the inside more negative. Sodium ions pumped out Potassium ions pumped in http://i-biology.net/

  10. Action Potential • Is the reversal (depolarization and restoration (repolarization) of the electrical potential across a plasma membrane as a nerve impulse passes along a neuron. • Resting potential is maintained by active transport: Na+/K+ pump pumps Na+ out & K+ in. • Arrival of an action potential causes depolarization of adjacent sections of the neuron. • If threshold is broken, voltage gated Na+ channels open and Na+ rushes in. Internal potential is reversed – it is more positive than the outside (depolarized). http://www.blackwellpublishing.com/matthews/actionp.html

  11. K+ channels are opened and K+ diffuses out. Internal charge is negative again (repolarization). Refractory period is when the channels rest between openings. This ensures one-way impulse flow. Resting potential is then returned by active transport. http://i-biology.net/

  12. Myelinated vs. Unmyelinated axons http://www.blackwellpublishing.com/matthews/actionp.html http://highered.mcgraw-hill.com/sites/0072437316/information_center_view0/#

  13. http://mindhacks.com/2005/09/27/synapse-wins-science-visualisation-contest/http://mindhacks.com/2005/09/27/synapse-wins-science-visualisation-contest/

  14. Synaptic Transmission: What happens when a nerve meets another nerve? • At the dendritic end of the nerve cell, vesicles containing neurotransmitters fuse with the axon terminals • Neurotransmitters (chemical signals) bridge the synaptic cleft gap. Use this tutorial: How does synaptic transmission work? http://outreach.mcb.harvard.edu/animations/synaptic.swf

  15. Summary of synaptic transmission Nerve impulse reaches terminal end of Pre-synaptic neuron Depolarization causes voltage-gated calcium channels to open. Ca2+ rushes in. Ca2+ causes synaptic vesicles to move to the membrane and fuse. Enzymes in the synaptic gap then break down the NT. The products are taken up to active transport (lots of mitochondria). Neurotransmitters (NTs) stored in the vesicles diffuse across the synaptic gap (cleft) Sodium channels open, causing Na+ to enter, leading to depolarization of the post-synaptic neuron. An action potential is initiated. NTs bind with post-synaptic receptors. NT’s are specific to the receptor. The nerve impulse is then propagated along the neuron.

  16. Draw and label a diagram of a motor-neuron, showing the direction of nerve impulse propagation. 3 marks.

  17. Draw and label a diagram of a motor-neuron, showing the direction of nerve impulse propagation. 3 marks.

  18. Explain how a nerve impulse passes along a non-myelinated neuron ( 8 marks). Action potential activates voltage-gated sodium channels; Sodium ions (+) rush in to axon; Potential increase; If it increases beyond threshold, more sodium channels open; Axon depolarizes, stimulating adjacent sections; Potassium channels open, potassium (+) rushes out; Potential is reduced (repolarization),; Refractory period ensures one-way conduction of action potential; Sodium-potassium pump returns axon section to resting potential.

  19. Use the correct answer to narrate this animation. Test yourself before I do. http://www.mrothery.co.uk/images/nerveimpulse.swf

  20. Explain the principles of synaptic transmission (8 marks).

  21. Explain the principles of synaptic transmission (8 marks).

  22. Outline the four methods of membrane transport in nerves and synapses (8 marks).

  23. Outline the four methods of membrane transport in nerves and synapses (8 marks).

  24. The Endocrine System

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