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Neurobiology for Majors > Exam 3 > Flashcards

Exam 3 Flashcards

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1
Q

Fill out what makes up the nervous system:
Nervous system –>
Nervous system –>

A

Nervous system –> CNS –> brain and spinal cord

Nervous system –> PNS –> somatic –> sensory and motor
PNS –> autonomic –> sympathetic and parasympathetic

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2
Q

What is a synonymous term for a muscle cell

A

Muscle fiber

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3
Q

What are skeletal muscles attached to?

A

bones (skeleton)

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4
Q

What is a fascicle?

A

A group of muscle cells surrounded by connective tissue

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5
Q

a) What is striated muscle?
b) Give 2 examples of striated muscles.
c) Are they under voluntary or involuntary control?

A

a) Muscle that has a striped pattern
b/c) Cardiac muscle (involuntary) & skeletal muscle (voluntary)

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6
Q

a) Where can smooth muscle be found?
b) Are they under voluntary or involuntary control?

A

a) Lining organs such as blood vessels, the gut, the lungs, and pupillary sphincter and dilator muscles.
b) Under involuntary control

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6
Q

What is sarcomere?

A

Repeating contractile unit in skeletal muscles that are involved in muscle contraction

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6
Q

Explain the general motor pathway to move a skeletal muscle of the body.

A

UMN –> LMN pathway

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7
Q

What does afferent mean?
What does efferent mean?

A

Afferent: coming to
Efferent: leaving from
For efferent, think about our effect on the world around us

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8
Q

What two motor neurons can be found in the ventral horn?

A

Alpha motor neurons and gamma motor neurons

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9
Q

What are the synaptic inputs to alpha motor neurons?

A

1) Input from DRG axons from the muscle spindle
2) Input from UMNs
3) Input from interneurons

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10
Q

What do alpha motor neurons innervate and what is their function?

A

Innervates skeletal muscle (extrafusal muscle) and causes muscle to move

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11
Q

What do gamma motor neurons innervate and what is their function?

A

Innervates muscle in the muscle spindle (intrafusal muscle). Modulates sensitivity of the muscle spindle stretch through control of intrafusal muscle inside the muscle spindle

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12
Q

Do alpha motor neurons or gamma motor neurons have larger cell bodies and axons?

A

Alpha motor neurons
APs will travel faster down alpha motor neurons

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13
Q

Where can grey matter be found? What about white matter? (In terms of the spinal cord)

A

Grey matter - inside the spinal cord
White matter - outside the spinal cord

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14
Q

Name each of the segments of the spinal cord from top to bottom.

A

Cervical, thoracic, lumbar, sacral

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15
Q

Define nerve plexus

A

Intertwining of spinal nerves in the PNS

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16
Q

What type of information does the brachial plexus correspond to?

A

Motor and sensory to upper extremities

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17
Q

What type of information does the lumbosacral plexus correspond to?

A

Motor and sensory to the lower extremities

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18
Q

How is the motor system organized in the head?

A

Collection of motor neurons in the brainstem send their axons out through cranial nerves to activate muscles in the head/neck

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19
Q

What is a cranial nerve?

A

A collection of nerves in the peripheral nervous system that have their nuclei in the brainstem

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20
Q

What does the oculomotor nerve (CNIII) control

A

Accommodation, pupillary dilator muscles, gaze

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21
Q

a) What does the facial nerve (CNVII) control?
b) What is a medical condition associated with dysfunction of this cranial nerve?

A

a) controls muscles of facial expression
b) Bell’s Palsy: partial face paralysis

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22
Q

a) What type of muscle is found in the iris?
b) What type of control is it under?

A

a) Smooth muscle
b) Involuntary control

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23
Q

a) What type of muscle will move the position of the eye?
b) What type of control is it under?

A

a) Skeletal muscle
b) Voluntary control

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24
Q

Explain the corticobulbar pathway

A

UMN in the PMC synapses onto a LMN in the brainstem (i.e. CNIII or CNVIII)

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25
Q

a) What do lower motor neurons activate?
b) How is this activation mediated?

A

a) voluntary muscles through contraction of skeletal muscle
b) activation of nicotinic receptors at NMJ

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26
Q

What 2 factors contribute to ion flow

A

Driving force and permeability

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27
Q

If you flex your bicep, extending your tricep, which muscle will be the agonist muscle and which will be the antagonist muscle?

A

bicep = agonist
tricep = antagonist

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28
Q

If you flex your tricep, extending your bicep, which muscle will be the agonist muscle and which will be the antagonist muscle?

A

bicep = antagonist
tricep = agonist

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29
Q

Explain the 3 factors that influence graded control of muscle function

A

1) frequency of motor neuron firing –> increased AP frequency increases in muscle force
2) recent additional synergistic motor units
3) recruit larger motor units

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30
Q

What is a motor unit

A

An alpha motor neuron and all the muscle fibers that it innervates

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31
Q

What will the size of a motor unit affect?

A

When activated they can be used to generate varying amounts of force

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32
Q

What is Myasthenia Gravis

A

An autoimmune disease linked to the production of autoantibodies against nAChR

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33
Q

What is spinal muscular atrophy (SMA)

A

Deletion/mutation of the SMN1 gene. It is a neurodegenerative disorder caused by the death of LMNs in the spinal cord and atrophy of muscles

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34
Q

Define UMN

A

A motor neuron that stimulates a LMN

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35
Q

What is area 6 of the motor cortex made from?

A

Premotor area (PMA) & supplemental motor are (SMA)

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36
Q

What part of the motor cortex requires the lowest level of activation to stimulate a movement

A

Primary cortex (M1)

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37
Q

a) What are the SMA and PMA involved in?
b) What type of musculature is activated by each?

A

a) Motor planning
b) SMA = distal musculature
PMA = proximal musculature

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38
Q

How many layers does the cortex have?

A

6 layers (laminar structure)

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39
Q

What can be found in cortical layer 5?

A

UMNs

40
Q

What do pyramidal cells in the primary motor cortex do?

A

Activate LMN

41
Q

What is a tract?

A

A bundle of fibers that travel through white matter

42
Q

Explain the anterior corticospinal tract (ACST)

A

An UMN in the PMC travels down to the spinal cord where it decussates there to provide bilateral input to LMNs that innervate axial muscles.
Important for postural control

43
Q

Explain the rubrospinal tract (RST)

A

Starts in the midbrain (specifically the red nucleus) and decussates almost immediately. It travels down to the spinal cord where it synapses in the ventral horn, allowing for movement of appendages.
Not very prevalent in humans

44
Q

Where does the somatic motor division carry information to?

A

Signals to skeletal muscles

45
Q

Where does the visceral motor division carry information to?

A

signals to smooth muscle, cardiac muscle, and glands

46
Q

What is the somatic motor component of the oculomotor nerve (CNIII)?

A

Gaze (eye movement)

47
Q

What is the visceral motor component of the oculomotor nerve (CNIII)

A

Accommodation and pupillary sphincter/dilator muscles

48
Q

a) What condition is associated with a lesion or damage to the lateral corticospinal tract (LCST)?
b) What are the signs/symptoms of this condition?

A

a) UMN syndrome
b) voluntary paresis, loss of RIFMs, spasticity, hyperreflexia, clonus, Babinski sign

49
Q

a) What two structures will signal to the vestibular nucleus?
b) What input will each send?

A

a) Vestibule and cerebellum
b) Vestibule = sensory input
Cerebellum = unconscious proprioception of where the head and body are in space

50
Q

Explain the vestibulospinal pathway

A

Auditory stimuli will activate vestibular nucleus in the brainstem (medulla). Important for neck movement towards stimuli

51
Q

What two places does the tectospinal pathway receive input from

A

visual and auditory input

52
Q

Explain the tectospinal pathway

A

Cell bodies in the Medulla will travel to the upper spine, decussating immediately in the medulla. Control auditory and visual reflexes

53
Q

What are the signs and symptoms of LMN syndrome

A

Paresis or flaccid paralysis, muscular atrophy, fibrillations, fasciculations, hyporeflexia

53
Q

What can be used to assess neuromuscular abnormalities?

A

EMG which measure the electrical currents of muscles

54
Q

What is the basal ganglia?

A

A collection of nuclei found in the deep gray matter

55
Q

What is the function of the basal ganglia

A

initiate, stop, and fine tune movements; learning and cognition

56
Q

What 2 structures make up the striatum

A

caudate nucleus and putament

57
Q

What do the ventral interior and ventrolateral thalamus do?

A

Provide excitatory input to the supplemental motor area

58
Q

What does thalamocortical excitation promote?

A

Initiation of desired movements

59
Q

Explain the general layout of basal ganglia circuitry

A

PFC –> striatum –> globus pallidus internus (GPi) –> thalamus (VA and VL) –> cortex (area 6) –> movement

60
Q

What happens when DA bind to D1R? How does cAMP influence synaptic transmission?

A

1) DA binds to D1R
2) Alpha-s subunit is released and interacts w/ adenylyl cyclase
3) This will increase cAMP intracellularly
4) cAMP will act on cAMP-gated ion channels and allow Na into the cell
5) cAMP will act on protein kinase A (PKA)
6) PKA will phosphorylate ion channels and act upon downstream transcription factors

61
Q

Explain or draw the direct pathway. What is its function?

A

1) PFC is activated –> glutamate to striatum
2) striatum activated –> GABA to GPi
3) GPi is less active –> activates the thalamus
4) thalamus more active –> glutamate to PMC
5) PMC activated –> initiate desired movement

62
Q

What is disinhibition?

A

Inhibiting an inhibitor

63
Q

What glutamatergic receptors are expressed in the striatum?

A

NMDA –> allows Na+ and Ca2+ to flow through
AMPA –> allows Na+ to flow through
BOTH are ionotropic

64
Q

What GABAergic receptors are expressed in the GPi

A

GABAA (ionotropic) –> allows Cl- to flow through
GABAB (metabotropic) –> G-alpha-i –> inhibition of adenylyl cyclase

65
Q

Explain indirect pathway

A

1) PFC activated –> glutamate to striatum
2) striatum activated –> GABA to GPe
3) GPe less activate –> less GABA to subthalamic nucleus
4) STN activated –> GPi activation
5) GPi activated –> GABA to thalamus
6) thalamus inhibited –> less glutamate to PMC
7) PMC inhibited –> inhibitory movement

66
Q

How does the substantia nigra pars compacta influence direct and indirect movements?

A

By releasing DA onto the striatum

67
Q

Where are metabotropic DA receptors differentially expressed?

A

On striatal neurons in indirect and direct pathways

68
Q

What pathway does each correspond to (D1 v D2)? Is it excitatory or inhibitory?

A

D1: excitatory; expressed in direct pathway
D2: inhibitory; expressed in indirect pathway
both expressed on striatal neurons

69
Q

Explain mechanism associated w/ D1R v D2R

A

D1: g-alpha-s –> stimulatory (increased cAMP)
D2: g-alpha-i –> inhibitory (decreased cAMP)

70
Q

Explain the direct/indirect pathway w/o DA. What happens if there is DA?

A

Cortex leads to SNpc DA release either onto D1R or D2R. D1R activates direct pathway, stimulating movement. D2R inhibits indirect pathway, stimulating movement

71
Q

What id there’s no DA in the SNpc?

A

SNpc will be able to turn on direct pathway but wouldn’t be able to turn of the indirect pathway

72
Q

What 3 main motor components does the basal ganglia control?

A

1) initiation of movement
2) inhibition of unwanted movement
3) fine tuning of movement

73
Q

What does the cerebellum control?

A

precise control of motor function

74
Q

What are motor neuron diseases?

A

Diseases that affect UMNs, LMNs, or other components of the motor system

75
Q

Explain the cortico-pontocerebellar pathway

A

motor cortex –> LMN on contralateral side –> synapse onto muscle for voluntary movement
cortex signals contralateral cerebellum thru pons to convey motor plan
dorsal spinocerebellar tract provides unconscious proprioceptive input to the ipsilateral cerebellum

76
Q

What is ALS

A

progressive n. degen. disease resulting in death of UMNs and LMNs

77
Q

What is the pathological signature common to almost all sporadic ALS and most familial ALS?

A

TDP-43 positive inclusions which cause formation of protein aggregates

78
Q

What is a unifying feature of many n. degen. diseases?

A

formation of protein aggregates

79
Q

Define lateral sclerosis

A

Death of UMNs in motor cortex results in demyelination of lateral corticospinal tract

80
Q

What are symptoms of UMN syndrome and LMN syndrome

A

UMN: paresis, loss of RIFMs, spasticity, hyperreflexia, clonus, Babinski sign
LMN: paresis or flaccid paralysis, muscle atrophy, fasciculations, fibrillations, hyporeflexia

81
Q

What factors play a role in sporadic and familial forms of a disease?

A

sporadic: gene x environment (more random)
familial: genes

82
Q

Which is more common: sporadic or familial?

A

Sporadic

83
Q

Is familial ALS dominant or recessive

A

dominant

84
Q

What are identified genetic mutation for familial ALS?

A

C9orf72
Sod1
TARDBP
FUS

85
Q

a) What other disease does fALS overlap with?
b) Which gene mutations/proteins are linked?

A

a) frontotemporal dementia
b) C9orf72, TDP43 aggregation

86
Q

What is TDP-43? Why is it important?

A

DNA and RNA binding protein. Its important for RNA transport and translation

87
Q

What is SOD1?

A

endogenous antioxidant that neutralizes superoxide

88
Q

What is superoxide?

A

A potentially harmful reactive oxygen species that oxidizes lipids

89
Q

What conversion does SOD1 facilitate?

A

superoxide –> H2O2

90
Q

What is a useful mouse model for studying ALS?

A

SOD1 G93A

91
Q

Explain 3 potential pathogenic mechanisms in ALS

A

1) oxidative stress
2) reduced glutamate reuptake –> excitotoxicity
3) secretion of neurotoxic factors by astrocytes

92
Q

What is spinal muscular atrophy?

A

autosomal recessive motor neuron disease that primarily impacts LMNs in the ventral horn

93
Q

What are the two types of SMNs and what’s the difference between them?

A

SMN1 and SMN2
SMN2 has the exclusion of exon 7 bc of nucleotide c.280. This produces nonfunctional proteins

94
Q

What happens in a homozygous SMN1 deletion?

A

Rely on SMN2 which cannot compensate

95
Q

How does nusinersen work?

A

RNA splicing to recover truncated SMN2 by promoting inclusion of exon 7

96
Q

What is the broad organization of the autonomic nervous system?

A

Preganglionic neurons

97
Q
A

Neurobiology for Majors (2 decks)

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