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Physiology II Exam 1 > CNS Organization > Flashcards

CNS Organization Flashcards

1
Q

Definition of PNS. Afferent vs efferent pathways

A

-made up of transmission pathways carrying info between the CNS and external/internal environments

  • afferent (sensory) -> carry TO the CNS
  • efferent(motor) -> carry AWAY from CNS
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2
Q

What does the PNS consist of?

A
  • cranial nerves
  • spinal nerves (31 pairs)
  • sensory receptors in the skin and wall of the gut tube, tendons, and skeletal muscles
  • motor end plates between motor neurons and skeletal muscle fibers
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3
Q

What is the ANS?

A
  • subdivision of PNS
  • entirely motor
  • innervates smooth muscle and glands
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4
Q

What are the two divisions of the ANS?

A
  • sympathetic (thoracolumbar)

- -parasympathetic (craniosacral)

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5
Q

nucleus vs ganglion

A

nucleus: aggregation of dendrites and nerve cell bodies in the CNS
ganglion: “ “ in the PNS

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6
Q

Nerve vs tract

A

nerve: bundle of fibers in the PNS
tract: bundle of fibers in the CNS

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7
Q

What is a commissure?

A

-tract in the CNS that crosses from one side to the other

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8
Q

What is the trophic, receptive, and the conductive unit in the neuron?

A

trophic: cell body
receptive: dendrite
conductive: axon

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9
Q

What are the two major branches of spinal nerves?

A
  • dorsal primary ramus

- ventral primary ramus

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10
Q

What are the two small branches from each spinal nerve before turning into a ramus?

A
  • white ramus communicans: carries myelinated preganglionic fibers
  • gray ramus communicans: carries unmyelinated postganglionic fibers back to the spinal nerve
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11
Q

What are the paravertebral ganglia?

A
  • linked together into a long chain on either side of the vertebral column in the thoracolumbar region
  • site of cell bodies of postganglionic sympathetic nerves
  • site of synapses between preganglionic myelinated sympathetic neurons and postganglionic nonmyelinated sympathetic neurons
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12
Q

What is a splanchnic nerve?

A

-a nerve supplying viscera

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13
Q

What is a prevertebral ganglion?

A
  • typically found anterior to abdominal aorta

- site of synapses between preganglionic myelinated sympathetic neurons and postganglionic nonmyelinated neurons

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14
Q

What are the components of a refl arc?

A
  • afferent pathway
  • efferent pathway
  • association neurons (interneurons)
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15
Q

What is a monosynaptic pathway?

A

-pathways consisting only of afferent neurons and efferent neurons. Each pathway has a single synapse.

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16
Q

What are polysynaptic pathways?

A

-pathways that include interneurons as well as afferent and efferent neurons. Each pathway has multiple synapses.

17
Q

Resting state cell body voltage

A

-65mV

18
Q

excited cell body voltage and how does this occur?

A
  • approximately -45mV

- due to influx of Na+

19
Q

inhibited cell body voltage and how does this occur?

A
  • 70mV

- due to influx of Cl- or efflux of K+

20
Q

What are the components of the somatosensory axis?

A
  • peripheral receptors
  • afferent neurons
  • spinal cord or brainstem
  • reticular substance
  • cerebellum
  • thalamus
  • somesthetic areas of cerebral cortex
21
Q

What is the somatosensory axis?

A

the sequence of structures involved in the transmission of a sensory signal from the peripheral receptors to higher brain centers

22
Q

The somatosensory axis afferent neurons are arranged in a series of 3, what are those three afferent neuron groups?

A
  • primary: synapse in the psterior horns of spinal cord or sensory nuclei in the brain
  • secondary: synapse in the thalamus
  • tertiary: synapse in the somesthetic areas of cerebral cortex
23
Q

What is the sequence of transmission of AP from higher brain centers to skeletal muscles?

A
  • motor cortex cerebrum
  • efferent pathways
  • effectors (skeletal muscles)
24
Q

What are the processing areas of the skeletal motor nerve axis?

A
  • basal nuclei in the telencephalon (putamen, globus pallidus, and subthalamic nuclei)
  • thalamis in the diencephalon
  • spinal cord reflexes
25
Q

ACh is typically excitatory, what is it secreted by?

A
  • pyramidal cells (cerebral cortex)
  • basal nuclei neurons
  • alpha motor neurons
  • preganglionic neurons of ANS
  • postganglionic neurons of the parasympathetic system
  • some postganglionic neurons of the sympathetic system
26
Q

What is NE and what secretes it?

A

-can be either excitatory or inhibitory

  • neurons located in the brain stem and hypothalamus
  • neurons in pons
  • postganglionic neurons of sympathetic system
27
Q

What is dopamine and what secretes it?

A
  • usually inhibitory

- most neurons originating in the substantia nigra

28
Q

What is glycine and what secretes it?

A
  • always inhibitory

- synapses in spinal cord

29
Q

What is GABA and what secretes it?

A
  • always inhibitory

- many areas in the spinal cord and cerebral cortex

30
Q

What is Glu and what secretes it?

A

-always excitatory

  • many sensory pathways entering the CNS
  • many areas of cerebral cortex
31
Q

What are some characteristics of dendrites?

A

-extend for long distances
-cannot transmit AP -> electrotonic conduction instead
-partially permeable to K+ and Cl-
-potential lost due to leakage
-gradual loss of potential as the depolarization spreads from the site of initiation results in decremental conduction
+signal is weaker the further from site of initiation

32
Q

What is electrotonic conduction? Why can dendrites do this?

A

-direct spread of electrical current by ion conduction in the dendritic fluids without generating AP

  • dendrites have few voltage gated channels
  • thresholds too high for AP to occur
33
Q

What is the dendritic firing rate dependent on?

A
  • if the neuron remians above the threshold for excitation, the neuron will fire repetitively
  • firing rate depends on the normal excitatory rate and on the changes in the excitatory rate due to superimposition of additional excitatory or inhibitory signals
34
Q

What is typical synaptic delay?

A

min time: 0.5sec

-time it takes to transmit a signal from a presynaptic neuron to a postsynaptic neuron

35
Q

Why is there a minimum delay between synaptic surfaces?

A
  • time to release neurotransmitter from the presynaptic neuron
  • diffuse across synaptic cleft
  • act on postsynaptic membrane
  • increase membrane permeability
  • inward diffusion of Na+
36
Q

What are the two sources of blood to the brain?

A
  • vertebral arteries

- internal carotid

37
Q

What is the name of the anastomosis between the two vertebral arteries and the two internal carotid arteries?

A

-circle of Willis

38
Q

What are the components of the Circle of Willis?

A
  • posterior cerebral arteries
  • posterior communicating arteries
  • internal carotids
  • anterior cerebral arteries
  • anterior communicating artery (unpaired)
39
Q

What is the CNS and what belongs in it?

A
  • consists of unpaired, bilaterally symmetrical structures extending along the longitudinal axis of the midsaggital plane of the body
  • consists of structures arising directly from the neural tube

-brain and spinal cord

Physiology II Exam 1 (6 decks)

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