Psych 115 Midterm 1 UCLA Exam Questions
and Answers 100% Pass
What are the three layers of protective layer called?
Meninges
- Dura Mater (thick outer layer)
- Arachnoid (Spongy middle layer)
- Pia Mater (thin inner layer)
What is the organ that constantly manufactures the CSF?
choroid plexus, which resides in hollow tubes and cavities called ventricles
Where does the action potential originate?
Integration zone (or active zone)
What are the three types of neurons?
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?
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?
efferent - output
afferent - input
What is the potential equation for a voltmeter?
V = C+ - C-
What is the driving force on a molecule and when is it zero?
- 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?
Ek = -80mV
ENa = +60 mV
ECl = - 90 mV
ECa = +120 mV
How do IPSPs work?
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?
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?
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?
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
Why is an AP called an "all or none" phenomenon?
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 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?
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?
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?
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?
Active - required ATP an pushes ions in the direction it wants REGARDLESS OF DRIVING FORCES
Passive - ion channels open or close to allow ions to flow according to electrochemical gradient in
direction of driving force
Which factors contribute to the ending of the action potential
- Na-K ATPase Pump
-Delayed Rectifier K+ channel
- Inactivation of Sodium channels
and Answers 100% Pass
What are the three layers of protective layer called?
Meninges
- Dura Mater (thick outer layer)
- Arachnoid (Spongy middle layer)
- Pia Mater (thin inner layer)
What is the organ that constantly manufactures the CSF?
choroid plexus, which resides in hollow tubes and cavities called ventricles
Where does the action potential originate?
Integration zone (or active zone)
What are the three types of neurons?
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?
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?
efferent - output
afferent - input
What is the potential equation for a voltmeter?
V = C+ - C-
What is the driving force on a molecule and when is it zero?
- 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?
Ek = -80mV
ENa = +60 mV
ECl = - 90 mV
ECa = +120 mV
How do IPSPs work?
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?
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?
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?
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
Why is an AP called an "all or none" phenomenon?
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 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?
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?
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?
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?
Active - required ATP an pushes ions in the direction it wants REGARDLESS OF DRIVING FORCES
Passive - ion channels open or close to allow ions to flow according to electrochemical gradient in
direction of driving force
Which factors contribute to the ending of the action potential
- Na-K ATPase Pump
-Delayed Rectifier K+ channel
- Inactivation of Sodium channels
