FOM 7.5.1

Question 1

Name the three types of synapses and describe their morphology.

Answer 1

Axosomatic, axodendritic, axo-axonic

Question 2

What are the two different synaptic signaling in the axon?

Answer 2

Electrical and Chemical

Question 3

Describe the chemical synapse.

Answer 3

Vesicle cluster. Clear space b/t membranes (pre- and postsynaptic)

Question 4

Describe the electrical synapse.

Answer 4

Very close apposition of membranes (Gap junctions), dense material in contact area

Question 5

What is the sequence of events at the chemical synapse? (10 steps)

Answer 5

1) Neurotransmitter stored in synaptic vesicles 2) Action potential 3) Depolarization, opening of volatage-gated Ca channel 4) Influx of Ca 5) Ca leads to synaptic vesicle fusion 6) NT into synaptic cleft 7) Bind receptor on postsynaptic membrane 8) Open/close postsynaptic channels 9) Change in exitability 10) Retrieval of vesicular membrane, endocytosis using clathrin

Question 6

What is the name of the 3 SNARE proteins found in the synapse? What are involved in?

Answer 6

Synaptobrevin, Snap-25, syntaxin Synaptic vesicle fusion

Question 7

What cleaves SNARE proteins resulting in inhibition?

Answer 7

Clostridial toxins (Botulinum toxins - BOTOX)

Question 8

Is electrical or chemical synaptic transmission faster?

Answer 8

Electrical

Question 9

Which is larger the neuromuscular junction or hippocampal synapse?

Answer 9

NMJ. Much larger

Question 10

What are the two autoimmune neuromuscular dz’s? What are the Ab’s targeting in each?

Answer 10

Myasthenia Gravis: postsynaptic acetylcholine receptors Lambert-Eaton Syndrome: Ca channels

Question 11

What two NT are solely inhibitory?

Answer 11

GABA (CNS) and Glycine (Spinal Cord)

Question 12

What are three main NT’s that can be both excitatory and inhibitory?

Answer 12

Acetylcholine, Glutamate, Dopamine

Question 13

What NT is affected in Parkinson’s?

Answer 13

Dopamine

Question 14

What is responsible for the difference b/t excitatory and inhibitory actions of a particular NT?

Answer 14

Differences in the ligand-gated receptor

Question 15

Describe the large scale propagation of an action potential.

Answer 15

Sensory signals, motor signals, muscle signals

Question 16

Describe the shape of an action potential.

Answer 16

Look at picture

Question 17

What pump is responsible for setting the resting membrane potential?

Answer 17

Na-K pump

Question 18

Where is Na high and K high?

Answer 18

Na high outside K high (Nah get out, K come in)

Question 19

What are the two types of driving forces for a potential?

Answer 19

Chemical (concentration) and Electrical

Question 20

Once the threshold of a potential is reached, which voltage-gated channel opens first? Which one closes last?

Answer 20

Na-gated opens first K-gated closes last

Question 21

In a nerve cell, where is the action potential generated?

Answer 21

The axon initial segment

Question 22

What synapses work on the nerve? (hint: they counteract one another)

Answer 22

Excitatory: excitatory postsynaptic potential (EPSP) - depolarization Inhibitory: Inhibitory postsynaptic potential (IPSP) - hyperpolarization

Question 23

How many axons can one Schwann cell wrap around?

Answer 23

One

Question 24

What is the name of the junction b/t Schwann cells?

Answer 24

Node of Ranvier

Question 25

What wraps around multiple axons in the CNS?

Answer 25

Oligodendrocyte

Question 26

Describe saltatory conduction.

Answer 26

The action potential jumps down the axon. Must cause action potential at the nodes of ranvier.

Question 27

What is MS?

Answer 27

Multiple Sclerosis; A disease of the central nervous system characterized by a variety of clinical problems arising from multiple regions of demyelination and inflammation along axonal pathways.