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NBDE 1 > Ch. 10 - Neurophysiology 2 > Flashcards

Ch. 10 - Neurophysiology 2 Flashcards

1
Q

What are the divisions of the parasympathetic postganglionic receptors?

A
  • Nicotinic
  • Muscarinic
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2
Q

What are all preganglionic autonomic neurons and all postganglionic parasympathetic neurons classified as?

A

Cholinergic

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3
Q

What are the cholinergic effects of:

  • preganglionic autonomic system?
  • postganglionic parasympathetic fibers?
A
  • Excitatory
  • Either excitatory or inhibitory (depending on the end-organ)
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4
Q

Describe the preganglionic nerve fiber and the postganglionic nerve fiber of the sympathetic nervous system.

A
  • Preganglionic - Myelinated, cholinergic
  • Postganglionic - Unmyelinated, adrenergic
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5
Q

What are the principal locations of Alpha-1 and Alpha-2 adrenergic receptors?

A
  • Alpha-1 - Vascular smooth muscle (skin, mucosa, GI) (Vasoconstriction)
  • Alpha-2 - Presynaptic nerve terminals, platelets, fat cells, GI tract wall
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6
Q

What are the principal locations of the Beta-1 and Beta-2 adrenergic receptors?

A
  • Beta-1 - Heart (increase heart rate, contractility)
  • Beta-2 - Skeletal muscle, bronchial smooth muscle (Vasodilation, bronchodilation)
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7
Q

What are the sensory (ascending) pathways, along with their stimuli?

A
  • Spinothalamic
    • Pain, temperature
  • Dorsal column, medial lemniscus
    • Touch, pressure, vibration, proprioception
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8
Q

What are the motor (descending) pathways?

A
  • Corticospinal (pyramidal)
  • Extrapyramidal
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9
Q

What makes up the spinal cord?

A
  • SAME DAVE
    • Dorsal horn - Sensory (afferent)
    • Ventral (anterior) root - Motor (efferent)
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10
Q

What are the 2 broad types of receptors and what is included in each of those types?

A
  • Exteroreceptors (external stimuli)
    • Touch, pressure, pain, temperature, light, sound
  • Internoreceptors (visceroreceptors)
    • Pressure, pain, chemical changes
    • Proprioceptors (position in space)
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11
Q

What are the different types of joint receptors?

A
  • Nonencapsulated
    • Free nerve endings
  • Encapsulated
    • Pacinian - vibration, pressure
    • Ruffini - stretch
  • Neuromuscular spindles - stretch
  • Neurotendons - tension
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12
Q

Which part of the spinothalamic tract transmits pain and temperature vs the tract that transmits light touch?

A
  • Pain & temperature - Lateral spinothalamic
  • Light touch - Anterior spinothalamic
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13
Q

What does the dorsal column and medial lemniscus system convey?

A
  • Touch, pressure, vibration
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14
Q

In the dorsal column, medial lemniscus system, what fibers use the Fasciculus gracilis and what fibers use the Faciculus cuneatis?

A
  • Fasciculus gracilis - lower extremities
  • Fasciculus cuneatis - upper extremities
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15
Q

How is the somatosensory cortex representation described?

A

Homunculus (body proportional to sense)

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16
Q

What are the 2 major systems of the descending motor tracts?

A
  • Corticospinal tract (pyramidal)
  • Extrapyramidal
17
Q

Where do the fibers of the corticospinal tract decussate?

A

In the medulla (pyramids)

18
Q

What does it mean that the corticospinal tract decussates in the medulla?

A

The right brain controls left somatic muscles, visa-versa

19
Q

What smaller tracts make up the extrapyramidal system?

A
  • Rubrospinal - posture, somatic muscle
  • Reticulospinal - locomotion
  • Olivospinal - motor learning
  • Vestibulospinal - head and neck muscles
  • Tectospinal - coordinates head, neck, eye
20
Q

Where does the extrapyramidal system tracts decussate?

A

In the pons - which means the right brain controls the left lower motor neuron

21
Q

If you hemitransect the right side of the spinal cord, you lose ______ motor control (________), and _________ pain and temperature sense (_________).

A
  1. Ipsilateral
  2. Corticospinal
  3. Contra-lateral
  4. Spinothalamic
22
Q

A lesion on one side of the spinal cord causes?

A
  • Ipsilateral motor loss (corticospinal)
  • Ipsilateral touch/sensory loss
  • Contralateral pain and temp loss (spinothalamic)
23
Q

What is the resting membrane potential in most cells, and heart cells?

A
  • Most cells - around -70mV
  • Cardiac cells - -90mV
24
Q

What is the threshold for an action potential?

A

20 mV+

25
Q

What is the “all or none” phenomenon?

A

If don’t reach threshold, dont get action potential

26
Q

What is responsible for the relative refractory period?

A

Hyperpolarization - an overshoot in the more negative direction during repolarization

27
Q

What are the excitable cells?

A
  • Neurons
  • Muscle cells
  • Cardiac pacemaker
28
Q

How do local anesthetics work?

A
  • Block sodium channels (decrease Na+ permeability)
  • Lowers membrane excitability –> can’t generate AP –> no nerve impulse conduction
29
Q

In what order does local anesthetics affect nerve fibers?

A
  1. Unmyelinated C-fibers (slow, dull, long lasting)
  2. Small myelinated nerve fibers (pain, temp)
  3. Large A-fibers (touch proproiception, golgi tendon)
30
Q

What is the major excitatory neurotransmitter?

A

Glutamate

31
Q

What are some examples of inhibitory neurotransmitters?

A
  • Glycine
  • GABA
    • Both bind receptors and open Cl- channels
32
Q

What is Spatial Summation?

A

When 2 excitatory inputs arrive at a postsynaptic neuron simultaneously - converging circuit

33
Q

What is Temporal Summation?

A

When 2 excitatory inputs arrive at a postsynaptic neuron in rapid succession

34
Q

What does myelin do?

A

Prevents movement of Na+ and K+ through membrane

  • Lowers membrane capacitance
  • Raises membrane resistance
35
Q

What does conduction velocity depend on?

A
  • Diameter of nerve fiber
  • Presence of myelin sheath
36
Q

Define these problems with nerve conduction:

  • Wallerian Degeneration
  • Neuropraxia
  • Axonotmesis
  • Neurotmesis
A
  • Wallerian Degeneration - axon is cut
  • Neuropraxia - transient block (bruise)
  • Axonotmesis - axon damaged, connective sheath remains intact
  • Neurotmesis - complete transaction of nerve trunk –> motor flaccid paralysis, atrophy of end-organ
37
Q

Which nerve fibers can regenerate, and where are they located?

A

Fibers of the PNS - with neurilemma (sheaths)

38
Q

How are nerve cells myelinated in the CNS vs the PNS?

A
  • CNS - oligodendrocytes with no neurilemma
  • PNS - Schwann cells with neurilemma

NBDE 1 (17 decks)

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