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Neuroscience > midterm > Flashcards

midterm Flashcards

1
Q

do dendritic projections function as input units or output units for a neuron?

A

they fx as main input sites for the cell (receive info from other cells)

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2
Q

what is an example of a pseudounipolar cell?

A

sensory neurons (retina)

have single projection from cell body that divides into 2 axon roots but no true dendrites

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3
Q

what is the specialized fx of multipolar cells?

examples?

A

to receive + accommodate huge amount of synaptic input to their dendrites

example: spinal motor neuron or purkinje

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4
Q

what are the 3 major ions that contribute to the electrical potential of a cell membrane in its resting state?

A

Na+
K+
CI-
Ca2+

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5
Q

What is depolarization? hyperpolarization?

A

depolarization = (excitatory) when membrane potential becomes less negative (or more positive) than the resting potential

hyperpolarization = (inhibitory) when membrane is more polarized than at rest

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6
Q

if a membrane channel opens when it is bound by a neurotransmitter, what type of membrane channel is it?

A

ligand gated channel

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7
Q

what does “graded” mean for a local receptor?

A

grading in amplitude and duration

a larger an dlong lasting stimulus results in a larger and longer lasting receptor potential

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8
Q

how is the resting membrane potential maintained?

A
  1. negatively charged molecules (anions) trapped inside the neuron (too large to diffuse)
  2. passive diffusion of ions through leak channels
  3. Na, K pumps
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9
Q

why is hyperpolarization of a neuronal membrane considered inhibitory?

A

because it triggers a refractory period in the cell

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10
Q

peripheral receptors have what types of ion channels?

A

modality gated channel

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11
Q

what are 2 types of local potential summation that can result in depolarization of a membrane to the threshold level?

A
  1. receptor potentials

2. synaptic potentials

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12
Q

the generation of an action potential requires the influx of what ion? What kind of channel controls it?

A

Na+

voltage gated channel

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13
Q

what characteristics of an axon promote faster conduction of an action potential?

A

larger diameter

myelination

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14
Q

what are the features of the nodes of ranvier that promote generation of an action potential?

A

contain high densities of Na+ & K+ channels
stores charge, preparing to produce new action potential (saltatory conduction)
maintains size as it travels

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15
Q

where are networks composed of interneuronal convergence + divergence found?

A

CNS and spinal cord

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16
Q

how do glial cells differ from nerve cells?

A

provide structure for the NS and info transmission

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17
Q

what are the 4 fxs of astrocytes?

A
  1. bidirectional communication through gap junctions
  2. maintenance (cleaning debris)
  3. nutrition
  4. provide pathway for migrating neurons
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18
Q

how do oligodendrocytes and schwann cells contribute to the NS?

A

form protective myelin sheath
oligo: in CNS
Schwann: in PNS

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19
Q

What are the differences between guillain-barre syndrome and multiple sclerosis?

A

GB: inflammation + demyelination of peripheral sensory & motor fibers. antibodies attack schwanns.

MS: CNS demyelination. antibodies attack oligodendrocytes.

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20
Q

what is the difference between posynaptic inhibition + presynaptic inihibition?

A

postsynaptic: decreases possibility of an action potential
presynaptic: decreased duration of an action potential (less neurotransmiter released)

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21
Q

what is an EPSP?

when does it occur?

A

Excitatory postsynaptic potential which occurs when neurotransmitters bind to postsynaptic membrane receptors that open ions channels

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22
Q

what type of activation results in a faster generation of a synaptic potential?

A

direct activation = faster

indirect activation = longer lasting

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23
Q

how long do the effects of neurotransmitter binding last? neuromodulator binding?

A

neurotransmitters: fast, short lived (1/1000 of sec)
neuromodulators: slowly (seconds)

24
Q

how does binding of a neurotransmitter to the receptor of a ligand gated ion channel cause the channel to open?

A

when the neurotransmitter binds to the receptor site of the membrane channel (lock and key)

25
Q

how do G-proteins contribute to cellular events?

A

idirectly open ion channels by moving between receptors and target effector proteins on the inside the cell membrane

26
Q

what is the effect of the neurotransmitter determined by?

A

depend on the type of receptor they bind with

27
Q

what transmitter + receptor is essential for long term potentiation?

A

glutamate

NMDA receptors

28
Q

when do the organs form during development?

A

embryonic stage (day 15 to end of 8th week)

29
Q

what are the steps in the formation of the neural tube?

A
  1. NS begins as neural plate (thickening of the ectoderm)
  2. edges of the plate fold to form neural groove
  3. at day 21, folds touch and tube is formed
  4. zips closed rostrally to caudally leaving open neuropores
30
Q

what is a myotome?

A

group of muscles derived from one somite + innervated by a single spinal n.

31
Q

what are the steps of changes from neural tube to brain?

A

when superior neuropore closes (day 28)

  1. tube exapnds to form hindbrain, midbrain, forebrain
  2. hindbrain divides into myelencephalon + metencephalon which eventually become the medulla + pons + cerebellum
  3. forebrain becomes diencephalon (which becomes thalamus + hypothalamus) and the telencephalon (which become cerebral hemispheres)
32
Q

what are the progressive processes of cellular development?

A

cells on neural tube divide to produce neurons + glia which migrate to final location and differentiate according to the area of the brain migrated to.

uses growth cone to project

33
Q

what is the regressive processes of cellular development?

A

neuronal death: death of neurons that failed to est. optimal connections with target cells during development or were too inactive

axon retraction from target cell

34
Q

what are the anatomic defecits for anencephaly, arnold chiari + 4 types of spina bifida?

A

anancephaly: rostral end of neurotube fails to close
arnold chiari: tonsil of cerebellum is herniated
spina bifida occulta: no displacement of SC
spina bifida meningocele: expanded subarachnoid space, no SC displacement
spina bifida myelschisis: displaced spinal cord
meningomyoseal: brain exposed

35
Q

what are the difference between arnold chiari type I and II?

A

Type 1: asymptomatic, enough space between tonsil and foramen magnum to not cause sx’s
Type 2: herniation of tonsil + spina bifida myomeningiseal

36
Q

what is often found with intellectual disability?

A

abnormalities of dendritic spines

37
Q

what are the types of CP?

what causes it?

A

caused by damage to UMN’s

  1. spastic: excessive contraction
  2. athetoid
  3. ataxic: uncoordination
  4. mixed: mix of more than one
  5. hypotonic: low muscle tone
38
Q

What is the difference between ventral roots and ventral rami?

A

venrtal roots prject from the cord and contain motor axons

ventral rami: innervate bone, muscle, skin. contain mixed spinal N

39
Q

what is a spinal segment?

A

connected to specific region of the body

40
Q

which of the rexed lamina is known as the substantia gelatinosa?

A

lamina I & II

41
Q

are the reflexes and the voluntary motor control areas separate systems?

A

they both use interneurons

42
Q

what is the fx of reciprocal inhibition?

A

decreases activity in antagonist when an agonist is active

43
Q

what do stepping patterns generators in the spinal cord control during walking?

A

the control flexor activation at certain times and extensor activation at other times to alternate movements

postural control, cortical control of dorsiflexion, afferent info is also needed

44
Q

how is voluntary voiding of urine controlled?

A

parasympathetic impulses stimulate bladder wall contraction + open sphincter, somatic efferent stop firing to allow relaxation of sphincter

45
Q

what is the difference in symptoms of segmental + vertical tract legiions?

A

segmental: one area

46
Q

when does the myelination of the axons begin?

A

during the fetal stage

47
Q

when does the endoderm, mesoderm and ectoderm develop?

A

during the pre embryonic stage

48
Q

when do the organs form?

A

during the embryonic stage

49
Q

During the embryonic stage, the longitudinal thickening of the ectoderm is called the

A

neural plate

50
Q

Somites are derived from which one of the following pre-embryonic cell layer

A

mesoderm

Somites are spherical cell clusters that develop from the mesoderm as the neural tube closes.

51
Q

what is the development of somites?
where do they appear and how are they added?

what does the sclerotome, myotome and dermatome become?

A

Somites appear in the occipital region, adjacent to the neural groove, and are added in a rostral-to-caudal direction.

anteromedial sclerotome becomes the vertebrae and skull
posteromedial myotome develops into skeletal muscle
lateral dermatome develops into the dermis.

52
Q

what do Neurons that develop in the ventral region of the neural tube become?
dorsal?
neural crest?

A

Interneurons and the motor neurons that innervate skeletal muscle

Neurons in the dorsal tube proliferate to form interneurons and projection neurons

neurons from the neural crest form autonomic neurons.

53
Q

Why are the caudate nucleus and the lateral ventricles C-shaped?

A

During growth of the brain, expansion of the hemispheres inferolaterally to form the temporal lobe results in the C-shape of the caudate nucleus and lateral ventricles.

54
Q

How does a growth cone alter the membrane of a target cell?

A

When the growth cone of a presynaptic neuron contacts its target cell, repeated release of neurotransmitter stimulates development of receptor sites on the postsynaptic membrane

55
Q

Where is the predominant site of damage to the nervous system in dyskinetic cerebral palsy?

A

basal ganglia

56
Q

what is tethered spinal cord?

A

Inferior cerebellum and medulla elongated, protruding into the vertebral canal

causes malformation of pons and medulla

Neuroscience (5 decks)

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