Lecture 1B: CNS Organization

Question 0

What is a nucleus in terms of nerves?

Answer 0

Group of dendrites and nerve cell bodies in CNS

Question 1

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

Answer 1

Spinal-31

Cranial-12

Question 2

What is a ganglion in terms of nerves?

Answer 2

Groups of dendrites and nerve cell bodies in the PNS

Question 3

What is a commissure?

Answer 3

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

Question 4

What is the difference between white and gray matter?

Answer 4

White is myelinated

Question 5

What does the splanchnic nerve supply?

Answer 5

Viscera

Question 6

What is a reflex arc?

Answer 6

Pathway that leaves from and returns to the CNS

Question 7

What is the difference between somatic and visceral pathways?

Answer 7

Somatic carries signals to skeletal muscle

Visceral carries signals to smooth or cardiac muscle

Question 8

What is the excitation of a neuron typically due to?

Answer 8

Influx of Na+ ions

Question 9

What is the inhibition of a neuron typically due to?

Answer 9

Influx of Cl- ion or efflux of K+ ion

Question 10

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

Answer 10

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

Question 11

What is the somatosensory axis?

Answer 11

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

Question 12

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

Answer 12

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

Question 13

What is the skeletal motor nerve axis?

Answer 13

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

Question 14

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

Answer 14

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

Question 15

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

Answer 15

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

Question 16

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

Answer 16

Neurons originating in substantia nigra

Inhibitory

Question 17

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

Answer 17

Synapses in spinal cord

Inhibitory

Question 18

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

Answer 18

Spinal cord and cerebral cortex

Inhibitory

Question 19

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

Answer 19

Sensory pathways entering CNS, cerebral cortex

Excitatory

Question 20

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

Answer 20

Electrotonic conduction

Question 21

Why do dendrites exhibit decremental conduction of electrical potential?

Answer 21

They are long with thin membranes which causes the gradual loss

Question 22

What is electrotronic conduction?

Answer 22

Direct spread of electrical current in dendrite without generating action potential

Question 23

Why do dendrites not have action potentials?

Answer 23

The threshold is too high for it to be reached

Question 24

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

Answer 24

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

Question 25

What are the two blood sources to the brain?

Answer 25

Vertebral and Internal carotid arteries

Question 26

What are the components of the Circle of Willis?

Answer 26

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