Physiology 4.2

Question 1

How does GABAa/Glycine affect the post-synaptic potential?

Answer 1

• ativate inotropic Cl- channels

- inhibitory

Question 2

How does GABAb affect the post-synaptic potential?

Answer 2

• activates K+ metabotropic channel
• closes Ca2+ channel
• inhibitory

Question 3

How does GABAc affect the post-synaptic potential?

Answer 3

• activates ionotropic Cl- channel
• only in retina
• inhibitory

Question 4

Is opening a Cl- or a K+ channel more likely to give a consistent inhibitory effect and why?

Answer 4

K+

reversal potential of K+ is -80 mV and Cl- is -70 mV

resting potential for the cell is usually -70 mV

Question 5

How does the concentration of Cl- change with development?

Answer 5

Early:
-Cl- moved into cell by Na-K-Cl co-transporter = high Cl- conc. inside cell

Later:

• K+/Cl- cotransporter keeps Cl- conc. low inside cell
• *co-transporter not expressed early in development!

Question 6

What is responsible for increasing the signal:noise ratio in the brain?

Answer 6

GABA in the interstitial fluid leads toa constant low-level of activation of GABAa receptors

Question 7

How can glycine have an excitatory effect?

Answer 7

• binds to NMDA receptors and makes them more sensitive to glutamate
• spillover in spinal cord leads to enhanced pain transmission at glutamate synapses

Question 8

Where is glycine mainly found?

Answer 8

brain stem

spinal cord

Question 9

What is strychnine?

Answer 9

-glycine antagonist
-leads to neuron firing
(inhibits an inhibitor)

Question 10

Which gradient is used by re-uptake transporters on the pre-synaptic terminal?

Answer 10

Na+

Question 11

Which gradient is used by the re-uptake vesicle transporters on the pre-synaptic terminal?

Answer 11

H+