Class Notes (836,290)
Canada (509,749)
Psychology (3,518)
PSY100H1 (1,627)
Lecture

Oct 2 Lec 4.docx

11 Pages
96 Views
Unlock Document

Department
Psychology
Course
PSY100H1
Professor
Michael Inzlicht
Semester
Fall

Description
Oct 2, Lec 4 Recap from last lec: • intracellular is negative bc of the proteins, and the proteins are too large to fit through the channels • resting membrane potential = potassium membrane = it’s called this bc some of the potassium channels are open so K+ can move freely and it’s balance by the llbm of the diffusion wanting it to leave and electrical forces wanting to pull it in. Sodium channels are primarily closed though. • Hyperpolarizing = making it more negative and thus even farther away from the threshold, so no action potential • Depolarizing = makes it more positive and only if we get it past threshold will we have an AP • AP’s travel down the axon. Myelinated is better because it’s quicker since you only have to jump from one node of renvier to the next • Voltage-gated sodium channel = the channel opens or closes depending on the voltage(must be threshold, generally) • One neuron communicates with another at the synapse 2 Type of Synapses (Specialized Junctions): • Human brain contains about 100 billion neurons with each neuron forming an avg of 1000 synapses • 1)Electrical: o fairly rare but widespread o narrow cleft (gap junction) = 2-4 nanometers o membranes have large channels o transmission along synapse resembles conduction along axon o nearly instantaneous o frequently found in neural circuits such as escape behv o cells directly stimulate each other by sending ions through across gaps through channels that actually touch o Excitatory signals ONLY o Requires large presynaptic neuron to influence a small postsynaptic • 2)Chemical: o exocytosis results in the release of neurotrans o wider synaptic gap = 20 nanometers o stimulate adjacent cells by sending chem messengers o can take up to several milliseconds o excitatory or inhibitory o neurotrans release, binds to postsynaptic receptor cite, termination of chem. signal, postsynaptic potential, and neural integration o small pre can influence large post Types of Receptors and Detection on the Postsynaptic Side: • 1) Ionotropic: o Neurotransmitters attach to the ~ receptor site: o Ions are released from pre an attach directly to an ion channel, causing it to open o Everything occurs at one particular point in one step. Receptor = ion channel o faster • 2) Metabotropic: o Neurotrans attaches to a G-protein receptor (G-proteins are active) and causes the G-protein to separate and attach to an ion channel o This causes the ion channel to open o 2-step process. Receptor is not the ion channel o Slower, often deals with modulation bc it has the time delay Methods to Deactivate Neurotransmitters in the synaptic cleft: • 1) Diffusion (neurotrans can be diffused away) • 2) Deactivation (broken down) • 3) Reuptake (reabsorbed) Neural Integration • Excitatory  membrane will be more positive, enough to hit threshold, thus AP fired • Inhibitory  membrane will be more negative, therefore, farther away from threshold, no AP • However since there are many synapses for a given neuron, it is the net effect that really matters. Ex. 1 excitatory and 1 inhibitory of equal strengths = no effect • 2 types of integration: o 1) Spatial Summation = inputs from all over cell converge at axon hillock and exert a cumulative effect on the neuron (AP only if threshold reached) o 2) Temporal Summation = excitation from one active synapse is sufficient to initiate AP , across time if there’s enough rapid firing to cause enough depolarization Postsynaptic Potential Summary • Action potential o 1 to 2 ms o Signalling within neuron o About 100 mV o All or none o Active o Voltage dependent Na and K • Excitatory (EPSPs)  slight depolarization, allows sodium in (ligand-gated) o Signalling between neurons o 5-10ms up to 100ms o Up to 20mV o Graded depolarization (not all or none = small changes that can sum together) o Small, local o Passive • Inhibitory (IPSPs)  slight hyperpolarization bc chloride in or potassium out (ligand- gated) o Signalling between neurons o Up to 15mV o 5 to 10 ms up to 100 ms o Graded hyperpolarization (not all or none = small changes that can sum together) o Passive o Small, local • * ligand-gated = opposite voltage-gated, dependent on neurotrans (= ligand) and how well it bound to ion channel. And presence or absence of ligand determines whether channel opens Neuromodulation: • Synapses between an axon terminal and another axon fiber • Axo-axonic synapses have modulating effect on release of neurotrans of target axon. Two types of this modulation: o 1) Presynaptic facilitation: makes it easier for axon to release neurotrans o 2) Presynaptic Inhibition: makes axon releasing neurotrans less likely • A 3 neuron apart from pre and post is the one that can modulate *Tetanus related to GABA = inhibitory CHAPTER 4 PSYCHOPHARMACOLOGY (lec content/slides only! No textbook readings needed.) Identifying Neurotrans: • Must be synthesized within neuron • In response to an AP, the substance is released in sufficient quantities to produce an effect on post cell • This effect should be possible to duplicate experimentally • There needs to be some mechanism to be able to stop the interaction between pre and post 3 Types of Neurotransmitters • 1) Small Molecule Transmitters: meets all or most of criteria, plays a vital role in neurotransmission. Ex. Ach • 2) Neuropeptides: at least 40. Act as neurotrans, neuromod, and neurohormones • 3) Gaseous Neurotrans: some gases transfer info from one cell to another o Most recently discovered form Characteristics of Specific Neurotrans: • Ach = Acetylcholine: o Found in neuromuscular junction, basal projections of hippocampus to amygdale o Involved with learning and memory, autonomic fxn, movement • Dopamine: o Basal ganglia and substantia nigra o Reinforcement, reward o Parkinsons’ • Norepinephrine: o Mood, arousal o Hypothalamus o Not really going to talk about this one • Serotonin: o Pons o Not gonna talk about this much o Sleep though, and appetite • Glutamate o Most widely distributed excitatory o Long-term memory • GABA o Most widely distributed inhibitory o Mood, seizure thresholds o Ex. Alcohol • Not gonna talk about ATP (energy molecule, pain modulation, CNS inhibition) • End
More Less

Related notes for PSY100H1

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit