Exam 2 - Lecture 23 (Synapse 1)

Question 1

How do neurons influence the excitability of other neurons?

Answer 1

Via synapses

Question 2

What is an example of synaptic action?

Answer 2

quadriceps reflex

Question 3

How does synaptic action work in the quadriceps reflex (4 ways)?

Answer 3

1. Stretch quads
2. Stretch muscle spindles of sensory neurons
3. Motor neurons in the ventral horn
4. Contraction of quads

Question 4

Where are synapses located?

Answer 4

between terminal branches of axons and neuronal cell bodies, dendrites, and axons of postsynaptic neurons

Question 5

What are the 3 classifications of synapses?

Answer 5

1. Axodendritic synapse
2. Axosomatic synapse
3. Axoaxonic synapse

Question 6

What is the synaptic bouton?

Answer 6

Terminal bulb of an axon

Question 7

What 2 things are found in presynaptic structures?

Answer 7

1. Synaptic vesicles with NTM

2. Pre-synaptic membrane

Question 8

What 2 things are found in postsynaptic structures?

Answer 8

1. Postsynaptic membrane

2. Ligand-gated receptors

Question 9

What is the space between pre- and post synaptic structures?

Answer 9

Synaptic cleft

Question 10

What do ligand-gated receptors do in the postsynaptic structure?

Answer 10

Open channels for specific ions (i.e. glutamate, ACh)

Question 11

What do excitatory neurons do?

Answer 11

Make excitatory synapses with postsynaptic neuron

Question 12

What do inhibitory neurons do?

Answer 12

Make inhibitory synapses with postsynaptic neuron (suppresses action of postsynaptic neuron)

Question 13

What is an example of why you need excitatory/inhibitory synapses?

Answer 13

For flexor or withdrawal reflex; if you step on a nail flexor muscle is stimulated but extensor is also inhibited so that they don’t oppose each other

Question 14

What happens in an excitatory synapse?

Answer 14

Excitatory NTMs are released and excite the postsyn. neuron

Question 15

What are the 2 excitatory NTMs and their receptors/where are they found?

Answer 15

1. Glutamate - GluR (CNS only)

2. ACh - AChR (CNS & PNS)

Question 16

What typically uses ACh as its NTM?

Answer 16

skeletal muscle

Question 17

What happens in an inhibitory synapse?

Answer 17

Inhibitory NTMs are released and inhibit postsyn. neurons.

Question 18

What are the 2 inhibitory NTMs and their receptors/where are they found?

Answer 18

1. Glycine - GlyR (CNS)

2. GABA - GABA receptor (CNS)

Question 19

What is another name for GABA?

Answer 19

gamma-aminobutyric acid

Question 20

What is a Renshaw cell?

Answer 20

Inhibitory neuron that receives its input from the motor neuron it is associated with; self-regulating mechanism

Question 21

What NTMs do Renshaw cells mainly release?

Answer 21

Glycine

Question 22

What are 2 examples of presynaptic deficits of inhibitory neurons?

Answer 22

1. Strychnine

2. Tetanus toxin

Question 23

What do Strychnine and tetanus toxin do?

Answer 23

Prevent release of glycine and GABA from inhibitory neurons and Renshaw cells.

Question 24

What occurs in Strychnine?

Answer 24

Nonfunctional Renshaw cells; over-activity of extensor muscles (no inhibitory action occurs to oppose extensor muscles)

Question 25

What occurs in tetanus toxicity?

Answer 25

Tetanu toxin binds to inhibitory neurons and stays there for > 4 weeks; over-activity of extensor muscles (no inhibitory action occurs to oppose extensor muscles)