Lecture 8

Question 1

Subthreshold, no summation

Answer 1

Multiple EPSPs happens, one after the other comes back to -70mV. No AP is fired

Question 2

Temporal Summation

Answer 2

Multiple EPSPs happen, one shortly after another, making the voltage pass threshold and fire and action potential

Question 3

Spatial Summation (EPSP)

Answer 3

Multiple EPSPs happen at the same time; fires an AP

Question 4

Spatial Summation (EPSPs and IPSPs)

Answer 4

EPSPs and IPSPs happen at the same time, cancelling each other out; no AP fired

Question 5

Metabatropic Receptors

Answer 5

• Receptors activate intracellular signals
• Longer-lasting than ionotropic
• Can activate a G-protein which activates second messenger to open ion channels, change gene activation, etc.

Question 5

What happens to neurotransmitters in the synaptic cleft?

Answer 5

• If nothing happened, they would be destroyed by enzymes
• Reuptake, or reabsorption of neurotransmitter by a neurotransmitter transporter in presynaptic neurons. Allows for recycling and stops activation

Question 6

Electrical Synapse

Answer 6

• A direct electric link between two neurons
• Gap junction connects neurons physically

Question 7

Glutamate

Answer 7

• Most common excitatory neurotransmitter in the nervous system
• Excitatory (induces EPSPs)
• Attaches to AMPA ionotropic receptors which allows flow of Na+ and K+
• NMDA glutamate receptors are ionotropic and allow flow of many ions (including calcium)
• mGluR metabotropic receptors also use glutamate
• Participates in many things, with emphasis on learning and memory

Question 8

GABA

Answer 8

• Gamma Amino Butyric Acid
• Most common inhibitory neurotransmitter (causes IPSPs)
• GABA opens a chloride channel on the post synaptic neuron, hyperpolarizing it
• GABAa and GABAb receptors

Question 9

Acetylcholine (ACh)

Answer 9

• Usually EPSPs
• Found both in the brain and PNS
• In brain: sensation, action, learning, attention
• In PNS: peripheral motor neurons and parasympathetic system
• Neurotransmitter at the neuromuscular junction: synapses between motor neurons and muscle fiber

Question 10

ACh Pathway in brain

Answer 10

• Only a small number of neurons release ACh in the nucleus basalis

Question 10

Acetylcholinesterase

Answer 10

• Clearing protein for ACh; degrades it

Question 10

Sarin and Consequence of High Sarin Exposure

Answer 10

Blocks acetylcholinesterase from degrading ACh, resulting in buildup of ACh. Consequence of sarin exposure is constant muscle contraction from ACh