151.L1.Lect14.15.Neur.12.11_13.13.Stu

Saltatory conduction of action potential myelinated

Info icon This preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: tatory conduction (of action potential) - myelinated neurons: ~150 m/sec - unmyelinated neurons: ~1m/sec 5. Release of neurotransmitter molecules from neuron 5. terminal (chemical signal; neurotransmission) terminal Fig. 43.2 Fig. Na+ channels open 1. Sensory stimulus (such as light) or neurotransmitter opens Na+ channels on a dendrite or cell body (ligand-gated) 2. Cell cytoplasm at (1) changes electrochemical gradient in positive direction by >20mV Campbell Figure 48.4 Fig. 43.2 Fig. Na+ channels open 1. Sensory stimulus (such as light) or neurotransmitter opens Na+ channels on a dendrite or cell body 2. Cell cytoplasm at (1) changes electrochemical gradient in a positive direction by >20mV 3. Voltage gated Na+ channels are progressively opened from site at (1) up to the axon hillock 4. Action potential WILL be generated at the axon hillock Campbell Figure 48.4 -50mV Before Na+ ion influx gets here Ll Fast responding Slow responding This action potential is an “all or none” event that begins at the axon hillock Campbell Figure 48.11 Slow responding http://outreach.mcb.harvard.edu/animations/actionpotential.swf -50mV Ll The influx of Na+ ions from the dendrites and cell body decrease the electrochemical gradient at the axon hillock to less than -50mV (moved >20mV in a positive direction) and above threshold Campbell Figure 48.11 http://outreach.mcb.harvard.edu/animations/actionpotential.swf +40mV Depolarization -50mV Ll Campbell Figure 48.11 http://outreach.mcb.harvard.edu/animations/actionpotential.swf Repolarization -50mV Ll Campbell Figure 48.11 http://outreach.mcb.harvard.edu/animations/actionpotential.swf -50mV -75mV Ll Undershoot: K+ channels are slow to close and neuron reaches about -75mV Na+ channels refractory to opening until electrochemical gradient is highly negative (such as below -50mV) http://outreach.mcb.harvard.edu/animations/actionpotential.swf Campbell Figure 48.11 -50mV Ll Na+/K+ ATPase pumps work together with other K+ “leak” channels to return the electrochemical gradient to -70mV Given the high concs. of ions in and arou...
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern