Reserve vesicles are continually generated and move

Info icon This preview shows pages 2–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Reserve vesicles are continually generated and move to docking proteins during NT release AP Exocytosis coupling o along the axon, Na+ carries the ionic current (depolarization) o in the axon terminal, Ca2+ carries the ionic current. Voltage-gated Ca2+ channels o Ca2+ acts as a “signal” for vesicle release o transfer from Na+ coming in to Ca2+ coming in o Ca2+ – in addition to carrying the chemical properties of an axon potential (depolarizing the membrane), it will also serve as a signaling molecule. Ca2+ comes into cell and interacts with the proteins around the vesicle. o 1. vessicles are docked o 2. Ca2+ enters (creating microdomain) o 3. Ca2+ activates SNARE proteins which releases vesicle (Ca2+ → synaptotagmin → v-, t- SNARES o 4. vesicle fuses with cell membrane releasing contents (exocytosis) o 5. vesicle membrane is recycled o note: Ca2+ acts as a signal; it is not membrane depolarization that directly triggers vesicle release o SNARE proteins are CA2+ sensitive. Series of SNARE proteins coupled with vesicle membrane and cell membrane proteins. Critical signal of Ca2+ coming in and acting on SNARE proteins causes changes in conformation such that vesicle can fuse with cell membrane. o Increase in NT's in synaptic cleft Summary of NT release o axon terminal responds to incoming AP by releasing NT. i.e. convert electrical into chemical signal Compartmentalization o dendrites have specialized proteins for chemical detection “receptors” o input into a neuron is based on chemical transmission which is turned into an electrical signal (i.e. generator potential) Postsynaptic Activity o two major receptor proteins. Some act as ion channels – ionotropic receptors: transmitter gated ions . Instead of responding to ionic environment around the membrane, Respond to chemicals in the extracellular fluid change permeability of membrane to specific ions e.g. Na+ ion channels sensitive to extracellular chemicals (NT receptors)
Image of page 2

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
excitatory post-synaptic potential (EPSP). Driven by communication across the synapse. Will cause a neuron to fire an AP. The main ions that cause EPSP are sodium and somewhat calcium o Inhibitory post synaptic potential (IPSP) – push membrane potential away from threshold, make neuron less likely to fire AP. Prevent it from getting to threshold. Mainly through Cl channels and sometimes K+ channels that are chemically gated. At rest, Cl equilibrium potential is close to membrane potential. That means that if ion channels are open, not much driving force of Cl to go in. however, if cell starts to depolarize, will generate driving force. “buffering system” buffer effect of EPSP channels that make the membrane more permeable to Cl- (or K+) oppose generation of AP. o metabatropic receptors – change intercellular chemical environment of the cell. Transmitter activated enzymes e.g. G-proteins Commonalities between transmitter-gating channel proteins o all ionotropic receptors have 5 subunits with each subunit comprised of four transmembrane domains o different receptors will have different interactions with NTs based on subunit compositions o “super family” of receptors o changing probability of channels making them more likely to open Recording Post Synaptic Potential o
Image of page 3
Image of page 4
This is the end of the preview. Sign up to access the rest of the 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