Lecture 1B: CNS Organization Flashcards

0
Q

What is a nucleus in terms of nerves?

A

Group of dendrites and nerve cell bodies in CNS

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1
Q

How many pairs of spinal and cranial nerves are there in the PNS?

A

Spinal-31

Cranial-12

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2
Q

What is a ganglion in terms of nerves?

A

Groups of dendrites and nerve cell bodies in the PNS

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3
Q

What is a commissure?

A

Tract in the CNS that crosses f rom one side to another

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4
Q

What is the difference between white and gray matter?

A

White is myelinated

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5
Q

What does the splanchnic nerve supply?

A

Viscera

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6
Q

What is a reflex arc?

A

Pathway that leaves from and returns to the CNS

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7
Q

What is the difference between somatic and visceral pathways?

A

Somatic carries signals to skeletal muscle

Visceral carries signals to smooth or cardiac muscle

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8
Q

What is the excitation of a neuron typically due to?

A

Influx of Na+ ions

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9
Q

What is the inhibition of a neuron typically due to?

A

Influx of Cl- ion or efflux of K+ ion

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10
Q

T/F: An action potential is reached no matter how many synapses fire simultaneously.

A

False, the action potential is determined by how many synapses fire simultaneously

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11
Q

What is the somatosensory axis?

A

Pathway that carries sensory signal from peripheral receptors to higher brain centers

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12
Q

Where do the 3 series’ of afferent neurons (of the somatosensory axis) each lead to?

A

Primary- From peripheral receptors to CNS
Secondary- Primary neurons to thalamus
Tertiary- Secondary neurons to cerebral cortex

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13
Q

What is the skeletal motor nerve axis?

A

Pathway of transmission of action potential from higher brain cetners to skeletal muscles

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14
Q

What is acetylcholine secreted by and is it excitatory or inhibitory?

A

Pyramidal cells, alpha motor neurons, preganglionic neurons of ANS, postganglionic neurons of parasympathetic system, some postganglionic neurons of sympathetic system
Excitatory

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15
Q

What is norepinephrine secreted by and is it excitatory or inhibitory?

A

Brain stem and hypothalamus neurons, neurons in pons, postganglionic neurons of sympathetic system
Excitatory or Inhibitory

16
Q

What is dopamine secreted by and is it excitatory or inhibitory?

A

Neurons originating in substantia nigra

Inhibitory

17
Q

What is glycine secreted by and is it excitatory or inhibitory?

A

Synapses in spinal cord

Inhibitory

18
Q

What is GABA secreted by and is it excitatory or inhibitory?

A

Spinal cord and cerebral cortex

Inhibitory

19
Q

What is glutamate secreted by and is it excitatory or inhibitory?

A

Sensory pathways entering CNS, cerebral cortex

Excitatory

20
Q

What form of transmission do dendrites use; action potentials or electronic conduction?

A

Electrotonic conduction

21
Q

Why do dendrites exhibit decremental conduction of electrical potential?

A

They are long with thin membranes which causes the gradual loss

22
Q

What is electrotronic conduction?

A

Direct spread of electrical current in dendrite without generating action potential

23
Q

Why do dendrites not have action potentials?

A

The threshold is too high for it to be reached

24
Q

What is the synaptic delay and what is the minimum time of delay?

A

Time it takes to transmit a signal from presynaptic to postsynaptic neuron.
Takes minimum of 0.5 seconds

25
Q

What are the two blood sources to the brain?

A

Vertebral and Internal carotid arteries

26
Q

What are the components of the Circle of Willis?

A
Posterior cerebral arteries
Posterior communicating arteries
Internal carotid arteries
Anterior cerebral arteries
Anterior communicating arteries