BIOL 101 1nd Edition Lecture 34 Outline of Last Lecture I Cell Mediated Adaptive Response II Cytotoxic T Cell III Self Nonself Complex Outline of Current Lecture I Nervous System II Central Nervous System III Peripheral Nervous System IV Nervous Tissue V Neurons VI Action Potentials VII Neurotoxins Current Lecture Class Discussion Nervous System I Parts of the Nervous System 1 Central Nervous System CNS Interprets and formulates responses to signals from the body These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute a Brain central controller of the nervous system b spinal cord sends signals to the brain and the body and vice versa 2 Peripheral Nervous System PNS Carries signals to and from the body and the spinal cord brain sends signals from sensory nerves to the brain and then the brain sends signals back a cranial nerves neurons that are directly connected to the brain b spinal nerves connected to the spinal cord 3 Nervous Tissue a Neurons aka nerve cells transmit electrical signals through the body i At rest the outside of the neuron is of the neuron is charged while the inside charged b Glial Cells support and nourish neurons i Myelin sheath insulates nerves and lets the signal move faster Myelin sheath is made up of glial cells called Schwann cells II How the Nervous System Works 1 Sensory Input where the PNS receives a signals from the outside world and sends it to the central nervous system 2 Integration brain formulates a response 3 Motor Output the brain sends signal to the body part telling it to respond in a certain way III DRAW A NEURON Try this at home Label and define dendrites cell body axon Schwann cells myelin sheath synaptic terminal synaptic vesicles DRAW AN AXON Try this at Label home ions ion channels what they do direction of ion flow IV Action Potentials how the neuron propagates a signal down the axon cell receives a stimulus the dendrites receive the stimulus the neuron will become slightly positively charged Action potential 1 threshold is the minimum increase in voltage required for an action potential to occur Threshold is reached sodium channels open sodium flows into the cell cell becomes positively charged 2 3when neuron reaches peak positive charge Potassium channels open and sodium channels close Potassium flows out of cell neuron becomes negatively charged again This makes potassium ion channels close again 4 5 V Sodium Potassium pump resets ion concentrations cell is now ready for the next action potential Action Potential Diagram GRAPH AN ACTION POTENITAL VI How Neurons Communicate With Each Other 1 AP gets sent down 2 NT released to synaptic cleft 3 NT binds to receptor 4 NT causes ions channels to open VII Neurotoxins 1 tetrodotoxin is found in puffer fish and is also found in Zombie Potions 2 TTX blocks the sodium channels in the axons so the action potential cannot propagate 3 This keeps signals from being sent through the body
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