PHIS 206 1st Edition Lecture 5 Outline of Last Lecture I Diffusion and Transport Review II Nervous System Units III Glial Cells 4 Types IV Neurons V Electrical Properties of Membranes Outline of Current Lecture I Electrical Properties of Membrane cont d II Neurons III Myelinated and Nonmyelinated IV Neurotransmitters Current Lecture I Electrical Properties of Membrane cont d All or nothing either generate action potential or do not Graded potentials only occur in the soma body Refractory period resistance to responding to a stimulus Consequences limits the of action potentials in a nerve Voltage gated channels embedded in neurons can be open or closed for a specific ion 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 The voltage gradient across the membrane determines whether it is open when threshold is reached or closed When it becomes more it means the neuron is further from the threshold Therefore it is harder to stimulate up to the threshold hyperpolarize II Neurons Inhibited neuron becomes MORE and harder to reach threshold with a stimulus Excited neuron becomes LESS and easier to reach threshold with a stimulus Action potentials CAN TRAVEL Rate at which they travel affects the rate at which information is transferred Slowest creators of action potentials NONMYELINATED axons faster as diameter of axon increases approx 1 3 ft s Myelinated axons can transmit action potentials faster approx 30 50 ft s III Myelinated and Nonmyelinated If we depolarize in the soma there will be a diffusion gradient Action potentials can only go AWAY from the soma In myelinated axons it is directly in contact with the membrane so it sets the rate for diffusion synapse where axon terminal pre synaptic of one neuron comes into contact with the dendrites or soma of another neuron post synaptic specialized structure with receptors on the post synaptic neuron IV Neurotransmitters One neuron only releases one neurotransmitter Most common neurotransmitter Acetylcholine ACh ACh in the synapse binds to receptors in the post synaptic cell Simulatenously the enzyme in the cytoplasm AChase breaks acetylcholine Acetylcholine Acetate Choline Stimulation decreases Acetate and Choline get actively transported and re synthesized RECYCLED cholynergic neurons includes motor neurons release ACh to help muscle cells
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