Lecture 5 : Synaptic Signalling

Question 1

what is the presynaptic ‘active’ zone

Answer 1

Part of presynaptic membrane where neurotransmitter release occurs.

• Docked synaptic vesicles ready for exocytosis
• Voltage gated Ca2+ channels
• Scaffolding proteins organising vesicle release

Question 2

What is post synaptic density

Answer 2

The postsynaptic density is a protein-rich structure on the postsynaptic membrane that organizes neurotransmitter receptors and signaling proteins

• Neurotransmitter receptors
• Scaffolding proteins that anchor receptors
• Signaling molecules that modulate synaptic strength and plasticity (plasticity is the synapses ability to strengthen or weaken over time in response to activity)

Question 3

What is meant by axodendritic, axosomatic and axoaxonic

Answer 3

These terms describe different types of synaptic connections based on where the axon terminal of one neuron synapses on another neuron.

• Axodendritic: Axon synapses onto a dendrite (most common, involved in excitatory/inhibitory signaling)
• Axosomatic: Axon synapses directly onto the cell body (soma) (strong influence on neuron firing).
• Axoaxonic: Axon synapses onto another axon (modulates neurotransmitter release, often inhibitory).

Question 4

Electrical effect of ionotropic receptor activation at an excitatory synapse

Answer 4

Question 5

Electrical effect of ionotropic receptor activation at an inhibitory synapse

Answer 5

Question 6

Spatial summation visualised, where the dotted line is the threshold potential

Answer 6

Question 7

Graph showing when threshold value is reached, synced to last flashcard

Answer 7

Question 8

For understanding, excitatory vs inhibitory synapse on a graph looks like this (due to spatial summation)

Answer 8

Question 9

What is meant by the all or nothing principle

Answer 9

• If the membrane potential reaches the threshold, a full action potential is triggered.
• If the stimulus is below threshold, no action potential occurs.
• The action potential always has the same strength and speed, regardless of stimulus intensity.
• Frequency of action potential firing is directly related to intensity of stimulus, so signalling is frequency modulated and not amplitude modulated

Question 10

Idk

Answer 10

Question 11

idk either

Answer 11