Synapse

Question 1

What is a synapse?

Answer 1

a junction between two cells where electrical changes in one cell cause a signal to be passed to another usually via a chemical neurotransmitter

Question 2

What is the function of chemical synapses?

Answer 2

transmit neuronal action potentials in one direction between cells

Question 3

What are the structures in a synapse?

Answer 3

• the synaptic cleft is the gap
• the presynaptic cell is before the gap
• the postsynaptic cell is after the gap
• the terminal of the presynaptic cell forms a swelling called a bouton

Question 4

How are changes in the resting membrane potential measured during synaptic transmission?

Answer 4

electrophysiology

Question 5

What are the 3 categories of synaptic activity?

Answer 5

1. presynaptic activity
2. postsynaptic activity
3. neurotransmitter deactivation

Question 6

Where are peptide neurotransmitters made?

Answer 6

the RER and Golgi

Question 7

Where are amino acid neurotransmitters made and packages?

Answer 7

in the bouton

Question 8

What is neurotransmitter release dependent on?

Answer 8

calcium

Question 9

What are the two types of receptors in the postsynaptic membrane?

Answer 9

G protein coupled (metabotropic)
ligand gated (ionotropic)

Question 10

What are the differences between EPSPs and action potentials?

Answer 10

1. EPSPs do not actively propagate along the axon
2. no voltage gated current in EPSPs
3. Na+ and K+ flow through the same non ion specific channel
4. EPSPS have no refractory period thus a series of EPSPs can summate

Question 11

What does a membrane potential crossing the action potential threshold depend on?

Answer 11

1. the inherent excitability of the neurone
2. the frequency or amount of incoming excitatory impulses
3. the frequency or amount of inhibitory impulses

Question 12

What does the inhibitory post synaptic potential (IPSP) do?

Answer 12

inhibits the membrane potential and so makes it harder for it to pass the threshold

Question 13

What does the excitatory post synaptic potential (EPSP) do?

Answer 13

increases the membrane potential and so allows the membrane potential to pass the threshold

Question 14

What happens when a neurone is excited and then inhibited?

Answer 14

it produces a rhythmic behaviour

Question 15

What happens when pain occurs?

Answer 15

• sensory pain neuron projects signal into the brain
• descending pain neuron excites the inhibitory interneuron
• inhibitory interneuron reduces the sensitivity of the ascending pain neuron

Question 16

What are the three main functions of chemical synapses?

Answer 16

computation
rectification
plasticity

Question 17

When is synaptic plasticity used?

Answer 17

• in memory and learning

- in addiction

Question 18

What is the relationship between dendrites and convergence?

Answer 18

the more dendrites a neuron has, the higher the degree of convergence

Question 19

What is the function of neuronal convergence?

Answer 19

easier for action potential to be reached

Question 20

What is the function of neuronal divergence?

Answer 20

harder for action potential to be reached

Question 21

What are the two types of feedback used to control neurones?

Answer 21

local neuronal feedback

long distance neuronal feedback