Synaptic Potentials

Question 1

How many synapse are in the CNS?

Answer 1

Recent estimates suggest there are more than 10 trillion synapse in the central nervous system!

Question 2

What is an Excitatory synapse?

Answer 2

synaptic connection where the release of NT’s leads to depolarization of the postsynaptic membrane, increasing the likelihood of generating an action potential in the receiving neuron.

Question 3

What is an Inhibitory synapse?

Answer 3

membrane potential of postsynaptic neuron is brought farther away from threshold (hyperpolarization) or stabilized at its resting potential

Question 4

Convergence vs Divergence

Answer 4

Question 5

What joins Pre - and post-synaptic cells?

Answer 5

joined by gap junctions

Question 6

What are Electrical Synapses?

Answer 6

• Electrical activity travels directly from the pre-synaptic cell to the postsynaptic cell ∴ communication is extremely rapid

Question 7

What are Chemical Synapses?

Answer 7

• Signal is transmitted by neurotransmitters
• Multiple NT’s can be released at the same time
• Each has a unique binding site on the postsynaptic cell
• Allows integration of multiple signals

Question 8

What are the Mechanisms of Neurotransmitter Release?

4

Answer 8

1. Ca2+ binds to Synaptogamins
2. Conformational change in SNARE complex
3. Vesicles fuse to Membrane
4. NT’s release into Synaptic Cleft

Question 9

How does the Activation of the Postsynaptic Cell begin?

What are Ionotropic and Metabotropic receptors?

Answer 9

Neurotransmitters reversibly bind to receptors on the post-synaptic cell membrane -> flux in [ion] and changes to the membrane potential

Ionotropic Receptors: ion channels
Metabotropic Receptors: indirectly affect ion channels

Question 10

What are the Mechanisms of Removal of Neurotransmitters from the Synaptic Cleft?

4

Answer 10

1. Reuptake by the presynaptic axon terminal for reuse (active transport)
2. Transported to and degraded by nearby glial cells
3. Diffusion from the receptor site
4. Enzymatically transformed into inactive substances (presynaptic cell may reuptake)

Question 11

What are Excitatory Chemical Synapses?
What is EPSP?

Answer 11

Question 12

What are Inhibitory Chemical Synapses?
What is IPSP?

5

Answer 12

Question 13

What is Synaptic Integration?

Answer 13

the process by which the postsynaptic neuron integrates multiple excitatory and inhibitory signals from various synapses to determine whether an action potential will be generated.

Question 14

Modification of Synaptic
Transmission – Drugs

Answer 14

Question 15

Recall

What is Botulism

Answer 15

• Toxins prevent ACh release from the axon terminal – specifically, neurotransmitter release is blocked due to the destruction of SNARE proteins
• Causes muscle weakness and paralysis