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Human Body_TP > CNS Physiology > Flashcards

CNS Physiology Flashcards

1
Q

spinal cord image

A

-you can see the individual vertebrae that extend down to L1 and L2 with nerve endings at the bottom
-covered by the meninges and the dura mater has CSF

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2
Q

where do afferent neurons project through?

A

dorsal horn of the spinal cord

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3
Q

where does the dorsal root ganglian sit?

A

-a foramen a distance from the spinal cord (intervertebral space)
-cell bodies project through dorsal horn and synapse with interneurons then exit through the ventral roots

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4
Q

what do the ventral nerve roots consist of?

A

motor neurons

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5
Q

where would you sample from if you want just the motor nerves?

A

-ventral nerve roots
-usually get torn away when you cut the spinal cord —> need a specific technique to get sample

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6
Q

where would you sample from if you want just the the sensory nerves?

A

-dorsal nerve roots
-also require a specific technique since you have to go ventrally to keep the ventral motor neurons intact

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7
Q

gyri

A

outpatchings of the brain

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8
Q

sulci

A

invaginations of the brain

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9
Q

different views of the brain for pathology

A
  1. coronal- patient is facing you
  2. sagittal- lateral view
  3. axial- think patient is feet forward so the patient’s right side is on the left side of the picture
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10
Q

what does the CSF do?

A

-cushions the brain and spinal cord
-supplies nutrients to the brain
-removes waste
-associated with arterial and venous blood supply —> constant turnover between the blood and CSF

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11
Q

how much CSF does the body produce?

A

-150 mls
-taking 50 mls can help with pressure of CSF and may transiently relieve patients
-drawing 20 mls can be used for diagnostics of MS or lyme since you cannot remove a piece of the spinal cord
-fluid is replaced within an hour

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12
Q

lumbar puncture

A

-method of sampling CSF
-helps with diagnostics
-emerging role with biomarkers in the CSF

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13
Q

gray matter

A

regions where the neurons sit

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14
Q

white matter

A

-axons of the neurons
-tracts are important pathologically

Ex. B12 deficiency selectively involves dorsal and cerebrocentral tracts —> patients will experience symptoms related to abnormalities of white matter tracts

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15
Q

spinal cord

A

-not just a straight tube
-cervical and lumbar regions, which are enlarged

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16
Q

cervical region

A

enlarged since this region innervates arms

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17
Q

lumbar region

A

consists of many motor neurons and is also enlarged since it goes to legs

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18
Q

thoracic region

A

less pronouncement since it is connected to the ribs and ribcage

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19
Q

cauda cana

A

-bottom portion of the spinal cord that looks like a horse’s tail
-nerve roots that exit through intervertebral parameter

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20
Q

spinal reflex

A

-afferent responses through dorsal root ganglion through dorsal horn that either synapse directly onto the motor neuron or the interneuron
-synapse activates muscle and inhibits through interneuron of hamstring so it can relax while the knee extends
-agonist/antagonist muscles are activated/inhibited

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21
Q

major pathways from CNS to PNS

A
  1. motor pathways
  2. sensory pathways
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22
Q

motor pathways

A

-in the homunculus you can see there are large representations of hands and legs, which is a graphical representation of amount of cortex innervating relevant regions
-hand with large representation along with face and tongue —> allows for fine motor movements
-axons travel through cerebral peduncle —> cross at pyramids —> descend down the corticospinal tract and synapse on motor neurons

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23
Q

sensory pathways

A
  1. dorsal column system
  2. spinothalamic tract
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24
Q

cell types of CNS

A

neurons, astrocytes, oligodendrocytes, microglia, and endothelial cells

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25
Q

cell types of PNS

A

schwann cells and muscles

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26
Q

anatomy of a neuron

A

-dendrites- branches that receive inputs from other cells
-cell body (soma)- contains the cell nucleus
-axon- conducts electrical impulses along the neuron cell
-myelin sheath- insulates the axon to help protect the cell and speed up transmission of electrical signals
-axon terminal- transmits signals

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27
Q

neuronal diversity

A

-unipolar
-bipolar
-pseudounipolar
-multipolar

Ex. Purkinie cell- anatomically laid out in cerebellum and shows how you have dendritic trees with axons that go deeper into the cerebellum

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28
Q

dendrites

A

-receive inputs
-consist of several branches that have buds where synapses are formed
-receptors sit on dendrites

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29
Q

soma

A

-nucleus
-mitochondria
-endoplasmic reticulum
-the typical cell functions

30
Q

axon

A

-axon hillock where the soma meets the axon and AP is established —> all the signals are synthesized here
-nodes of ranvier
-myelin sheath to help transmit electrical signals

31
Q

structural components of axon

A

-microtubules
-neurofilaments
-measured in blood and CSF –> cut a nerve and you can see these structures

32
Q

microtubules

A

-larger, longer polymers with tubular dimers and lots of proteins
-how things like mitochondria are trafficked up and down the axon

33
Q

neurofilament subtypes

A

-the light (NFL)
-the medium (NFM)
-the heavy (NFH)
-relevant b/c they can be measured in blood and CSF —> cut a nerve you can see neurofilaments, which can be used as biomarkers

Ex. look at the changes in neurofilaments over time for ALS

34
Q

axoplasm

A

cytoplasm of axon with complexity in structure

35
Q

types of axonal transport

A

-retrograde
-anterograde

36
Q

retrograde transport

A

-slow, backward movement of components like RNA, proteins from distal end to soma using microtubules
-occurs with dynatin and dynein

37
Q

anterograde transport

A

-fast, forward-moving
-occurs with kinesin

38
Q

myelin sheath

A

-insulation and has lamelle to wrap around axon
-between the regions you have the nodes of ranvier, which allow for rapid transmission

39
Q

nodes of ranvier

A

enrichment of Na channels within node and helps move AP down axon

40
Q

excitability of neuron

A

-transmit electrical signals down axon
-gather data in dendrite, synthesize in the soma, and transmit via the axon
-dependent on semi-permeable membrane with Na/K pump, Na channels and K channels —> pump brings in K and out Na in 3:2 ratio and keeps cell at resting membrane

41
Q

action potential

A

-stimulate the neuron electrically, mechanically, etc.
-Na channels open locally in response to stimulus generating an AP
-Na floods into the cell and AP starts to travel left to right
-as depolarizing current travels down, more Na channels open and you get propagation of AP
-at the same time, upstream Na channels inactivate after only being open for a brief amount of time and K channels start to open and membrane potential is restored

42
Q

saltatory conductions

A

-only occurs in regions between myelin sheaths
-regions consist of Na channels
-AP only has to occur with regions between myelin sheath
-helps propagate the AP along axon

43
Q

EMG/nerve conduction study

A

average speed of shocking the medial nerve is 49 m/s and in those with guillain-barre syndrome, it decreases from 49 to 21 m/s since the myelin is gone

44
Q

neurotransmitters

A

-classical: acetylcholine (NMJ transmission), dopamine (Parkinson’s disorder), serotonin (depression)
-amino acid: glutamate (most neurotransmission in brain is from this), aspartate, GABA (stiff person syndrome- immunity against GAD and prevents the production of GABA), d-serine
-peptides: tachykinin (substance P), opiate (enkephalin), somatostatin, cholecystokinin, vasoactive intestinal peptide
-gaseous: nitric oxide, carbon monoxide

45
Q

neuronal excitation and inhibition

A

-tells the difference between light and deep touch
-when Na channels are activated, they produce excitatory postsynaptic potentials (EPSPs)
-when Cl channels are activated, they produce inhibitory postsynaptic potentials (IPSPs)

46
Q

inhibitory synapse (glycinergic synapse)

A

released from presynaptic terminal of inhibitory neuron and Cl flows into the postsynaptic membrane

46
Q

how come we don’t respond to every stimulus?

A

EPSPs and IPSPs are synthesized and added up

47
Q

integration

A

-inhibitory and excitatory signals are summed up anatomically and temporally
-occurs in the neuropil, usually at the initial segments

48
Q

synaptic potentials

A

-stimulus from one excitatory input does not reach threshold so no AP fired (APs are all or nothing)
-if neuron fires twice quickly, temporal summation to generate AP
-two excitatory synapses fire together —> generate AP
-inhibitory synapse and excitatory synapse —> no AP generated

49
Q

what forms the CNS myelin?

A

-oligodendrocytes
-one oligodendrocyte can myelinate segments of many different axons
-only has one single layer of myelin

50
Q

astrocytes and health

A

-things wrong with astrocytes affect disease and health
-help with metabolism of brain and spinal cord

51
Q

synaptic transmission

A

presynaptic:
package neurotransmitter —> vesicle fuses to presynaptic membrane —> Ca signals fusion and release of neurotransmitters into synaptic cleft
postsynaptic:
receptors on membrane receive the neurotransmitters

52
Q

synaptic proteins

A

more than 1000 proteins function in the presynaptic nerve terminal and over 100 of them function in exocytosis

53
Q

acetylcholine

A

neurotransmitter that is the mechanism by which the nerve and muscle are connected

54
Q

biomarkers for ALS and other neurological disorders

A

-CSF
-blood/plasma/serum
-brain/spinal cord tissue but difficult to repeat since you can’t go back in for more samples
-urine
-skin has nerve fibers and proteins
-muscles
-electrophysiology
-PET imaging

55
Q

genetics for ALS

A

rise in discovery of genes contributing to ALS, which can be made into models

56
Q

induced pluripotent stem cells (IPSCs)

A

-yamanaka discovered that you could take mature cells and reprogram them to be immature
-he then discovered that he could reprogram the mature cells to become pluripotent stem cells, which are immature cells that are able to develop into all types of cells in the body

57
Q

PNS

A

-cranial nerves exit from brain and brainstem
-divided into somatic (muscles) and autonomic

58
Q

what do the dorsal root nerves consist of?

A

sensory neurons

59
Q

what happens once nerves emerge from the dorsal and ventral roots?

A

once they emerge, they are mixed nerves with sensory and motor fibers

60
Q

normal pressure hydrocephalis

A

buildup of CSF pressures —> perform high volume tap to provide transient relief

61
Q

dorsal column system

A

involved with fine touch and proprioception, which helps you know where you are in space

Ex. B12 deficiency patients sometimes have a hard time walking and not b/c they are weak but they are unable to sense their legs —> tell them to look down and they are able to walk

62
Q

spinothalamic tract

A

pain and temperature

63
Q

two types of myelin sheath

A

-oligodendrocytes in the CNS
-schwann cells in the PNS

64
Q

dendritic spine

A

-regions within dendrites where synapses are formed
-there has been research on these and how their morphology changes

Ex. LTP is a remodeling of neurons to form memories and promotes the growth of new spines

65
Q

what are some functions of astrocytes?

A

-@ synaptic sites, they are sucking up excess neurotransmitters like glutamate
-releasing neurotransmitters
-things that go wrong with astrocytes can affect synapses

66
Q

neuromuscular junction

A

-acetylcholine (A) is released from the motor neurons
-A binds to A receptors —> NA channels open and the muscle depolarizes
-AP opens the T tubules and SR with stores of Ca that is released
-as Ca binds, there is conformational change to allow actin filaments to bind to myosin
-overall: acetylcholine interacts with the membrane of muscle resulting in Ca release to allow for muscle contractions

67
Q

sensory pathways

A

-receptors can be mechanoreceptors, tactile fibers around hair, Pacini’s corpuscle
-they transmit all different sensory responses
-sensory neurons can become refractory (desensitized)
-different axon types come in different modalities

68
Q

if there is phenotypic heterogeneity in neurological diseases, are all mechanisms of ND similar?

A

-some patients with ALS have speech and swallowing as first symptoms while others have weaknesses
-all mechanisms of neurodegeneration are similar

69
Q

what can we do with IPSCs?

A

-record from them electrophysiologically
-mix and match them- take astrocytes from ALS and mix with normal motor neurons
-induce cell stressors
-drug screening

70
Q

what amino acid is involved in an inhibitory synapse?

A

glycine

71
Q

what amino acid is involved in an excitatory synapse?

A

glutamate

Human Body_TP (7 decks)

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