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43 Cards in this Set

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Synaptic vesicles
Located at chemical synapse
Active Zones
On the presynaptic membrane where vesicles are clustered.
How is signal transmitted at chemical synapse?
Via NTs
In electrical synapse, how are pre and post synaptic membrane joined?
Via gap junctions
What are the required steps for releasing NTs at chemical synapse?
1. AP arrives at membrane and depolarizes it.
2. Depolarization causes voltage gated Ca channels to open.
3. Ca enters cell and cause fusion of synaptic vesicles with the presynaptic membrane.
4. NTs released and some bind to receptors in postsynaptic membrane.
5. Receptors activated, open pores, causing depolarization or hyperpolerization of postsynaptic membrance.
6. NTs get degraded.
Synaptotagmin
It's a protein in synaptic vesicles that binds to Ca.

Helps to associate SNARE protein.
Postsynaptic receptors are made of what?
Ion channels.
EPSP
Excitatory PostSynaptic Potential.

Receptors that make the membrane potential to be slightly positive.
EPSP is due predominantly to what influx?
Na
Name two examples of excitatory NTs?
ACh and Glutamate
IPSP
Receptors for inhibitory NTs that make the membrane potential more negative.
IPSP is due to what iion influx?
Cl
Name two examples of inhibitory NTs.
GABA and Glycine
NOTE: a single EPSP is about .5mV.

What is the threshold for action potential using EPSP?
-55mV.
Therefore, you need a lot of EPSP to generate an AP.
How is an AP generated under the EPSP influence?
Through summation.
Temporal summation
When one EPSP is added upon another from A SINGLE NEURON, and you get a bigger EPSP.
Spatial summation
A way of achieving an AP in a neuron from multiple cells.
Why is a synapse near the initial segment has greater effects on AP than a synapse in the outer most branch of a dendrite?
The initial segment has a higher density of voltage gated Na channels and this makes the threshold at the initial segment lower than the threshold in cell body and dendrites.

Therefore, the location of individual synapses in the postsyn. cell affects the degree of a postsyn potential.
Motor end plate
The synapse that is located at the neuromuscular junction. Consisted of the axon terminal of motor neurons projected to muscles.
What makes up Ach?
Choline and acetate.
Name two types of Ach receptors.
Nicotinic and Muscarinic
Nicotinic receptor
An ion channel that moves na in and K out.

This type of receptor is called ionotropic receptor.
Muscarinic receptor
A G protein coupled receptor.

This type is called metabotropic receptor.
Glutamate
The most common NT in the CNS.

Have ionotropic receptors and metabotropic receptors.
GABA and Glycine
Inhibitory NTs.

Both move Cl ion into neurons.
What are two types of GABA?
GABA-a (ionotropic) and GABA-b (metabotropic)
Biogenic amines
Synthesized from amino acids and contain an amino group.
What's a common example of biogenic amines?
Catecholamines
Catecholamines are derived from where?
Tyrosine
How is epinephrine formed from tyrosine?
Tyrosine--> L-Dopa--> NE---> Epi
What compound destroys the catecholamine?
Monoamine oxidase.
What organ secretes epi?
Adrenal medulla
What are adrenergic neurons?
Neurons that release epi or NE.
Serotonin
Another biogenic amine. Synthesized from tryptophan.

Level is lowest during sleep and highest during state of alert.
What are the five classes of receptors?
Mechano
Thermo
Chemo
Photo
Noci
Sensory receptor
Are Either Specialized endings of afferent neurons or separate cells that can signal afferent neurons by releasing chemical messengers.

Can receive stimuli from external or internal environment.
How does a sensory receptor work?
At the receptor ending, an stimulus is transformed into an electrical signal which leads to opening or closing of particular ion channels.

This can lead to a production of membrane potential.
Receptor potential
A graded potential. A transmembrane potential difference in a sensory receptor.
Sensory Coding
Converting a stimulus energy into a signal that convey sensory info to CNS. Has to be precisely coded and delivered to CNS before our body can precisely respond to the stimulus.
Modality
A stimulus type.
Stimulus intensity
Coded as frequency of AP.

Ex. Increased stimulus strength means a larger receptor potential and a more frequent action potential firing.
Stimulus location
Spatial distribution of activated receptors.

Neuron with small receptive field can locate a stimulus more precisely.
Lateral inhibition
Information at edge of stimulus is strongly inhibited than info at center of stimulus.

Enhances the contrast btw periphery and center of a stimulated region, thereby increasing the brain's ability to localize a sensory input.