CNS Structures

Question 1

where are the first, second, and third synapses of the afferent pain/temp path? Where does it decussate?

Answer 1

• first: DCML in spinal cord
• second: thalamus
• third: somatosensory cortex (diffuse projection)
• decussation: spinal cord

Question 2

where are the first, second, and third synapses of the afferent proprioception/fine touch path? Where does it decussate?

Answer 2

• first: brainstem
• second: thalamus
• third: somatosensory cortex
• decussation: brainstem

Question 3

Describe optogenetics.

Answer 3

1. light sensitive protein from algae = ion channel that opens in response to blue light
2. take gene for this protein and insert into specific neurons of the brain
3. shine blue light to only fire those specific neurons

Question 4

TRUE or FALSE: EPP’s have a 1:1 excitation of the fiber.

Answer 4

TRUE: very specific

Question 5

Describe the start to finish of an endplate potential.

Answer 5

1. Ca2+ enters the neuron (synaptic terminal) and causes ACh to be released into the synaptic cleft
2. ACh binds to receptor on nicotinic ion channel (on skeletal muscle fiber)
3. Na+ and Ca2+ go into the skeletal muscle fiber to cause depolarization
4. K+ goes out of the skeletal muscle fiber

Question 6

TRUE or FALSE: skeletal muscles are always presynaptic to motor neurons.

Answer 6

FALSE: motor neurons are always presynaptic to skeletal muscles