Psych 115 Midterm 1 UCLA Exam Questions and Answers 100% Pass
What are the three layers of protective layer called? - Answer- Meninges
- Dura Mater (thick outer layer)
- Arachnoid (Spongy middle layer)
- Pia Mater (thin inner layer)
What is the organ that constantly manufactures the CSF? - Answer- choroid plexus, which resides in hollow tubes and cavities called ventricles Where does the action potential originate? - Answer- Integration zone (or active zone) What are the three types of neurons? - Answer- Multipolar - with multiple dendrites coming off the soma Bipolar - just 2 processes sticking off soma Unipolar - just one extension form soma that branches off into two How do excitatory, inhibitory, and modulatory neurotransmitters differ? - Answer- excitatory - depolarize post synaptic neuron and increases likelihood of post synaptic action potential inhibitory - hyperpolarize post synaptic neuron and decreases likelihood of AP modulatory - has multiple effects on post synaptic target What is the difference between efferent and afferent? - Answer- efferent - output afferent - input What is the potential equation for a voltmeter? - Answer- V = C+ - C- 1 / 3
What is the driving force on a molecule and when is it zero? - Answer- - Sum of both electrical force (determined by charge of membrane & ion) & chemical force (determined by concentration gradient) acting on ion
- its zero either when both forces are zero OR when they are equal and opposite
What are the approximate equilibriums for each molecule? - Answer- Ek = -80mV ENa = +60 mV ECl = - 90 mV ECa = +120 mV How do IPSPs work? - Answer- Inhibitory Post-Synaptic Potential - when an inhibitory transmitter such as GABA is released from synapse and binds to receptors such as ligand gated chloride channels which make membrane potential more negative which leads to hyperpolarization of membrane preventing it from making an action potential How do EPSPs work? - Answer- Excitatory Post Synaptic Potentials - when the excitatory neurotransmitter (glutamate or acetylcholine) is released & binds to ligand gated sodium ion channels which depolarizes cells and makes it more likely to fire AP What is the passive propagation of the EPSP? - Answer- When the EPSP gets smaller as it travels from the synapse to the axon hillock (integration zone) How can spatial summation and temporal summation help with the passive propagation of the EPSP? - Answer- Spatial summation - if two presynaptic neurons fire simultaneously the two EPSPs will sum to create a larger EPSP Temporal Summation - creation of large EPSP from two smaller EPSPs occurring in rapid succession at a single synapse 2 / 3
Why is an AP called an "all or none" phenomenon? - Answer- As soon as membrane is depolarized above spike threshold, an AP will occur.
- This is because opening voltage gated sodium channels will allow sodium to enter and
- / 3
depolarize membrane, which opens ever more channels (positive feedback cycle) How do the 4 protein subunits that make up the voltage gated sodium channel influence its 3 different states? - Answer- Physical configurations of subunits change for each state Closed - Na+ cannot pass through pore, when cell is hyperpolarized Open - Na+ ions can flow freely, happens when depolarization occurs, but quickly switches to inactive after millisecond Inactive - Na+ cannot pass through pore, channel cannot be opened even if depolarized, must go back to closed state through hyperpolarization before another AP What is the role of the delayed rectifier channels? - Answer- Open at -45mV to help potassium ions get out faster, they open slowly to allow spike to reach its peak -only has 2 states, open (when membrane depolarized above delayed rectifier threshold) and closed (when below threshold) After sodium moves into cell and potassium moves out because of the AP, how do they go back to equilibrium? - Answer- Na-K ATPase Pump which ejects 3 sodium ions for each 2 potassium ions imported, which repolarizes membrane at the end of AP What is the difference between active and passive transport? - Answer- Active - required ATP an pushes ions in the direction it wants REGARDLESS OF DRIVING FORCES