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Human Body_TP > Nervous System Histology > Flashcards

Nervous System Histology Flashcards

1
Q

CNS vs PNS

A

CNS:
-comprised of the brain and spinal cord as well as the olfactory and optic nerves
PNS:
-includes all parts of the nervous system that are outside of the CNS

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2
Q

functions of CNS vs PNS

A

CNS:
-receives and processes sensory info
-responds to sensory input with motor output instructions
PNS:
-sends sensory info to the CNS
-transmits motor output instructions from the brain to designated muscles and glands

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3
Q

autonomic nervous system

A

-involuntary
-comprised of the parasympathetic and sympathetic divisions

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4
Q

somatic nervous system

A

-voluntary skeletal muscles
-sensory and motor

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5
Q

two types of cell groups in the nervous system

A

neurons and glial cells

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6
Q

neurons

A

-conduct APs
-process signals
-contain dendrites, somas and axons

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7
Q

glial cells

A

-do not generate electrical impulses
-support and protect axons —> form myelin sheath around axon, remove cellular debris, and provide structural support

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8
Q

different types of neurons

A

-motor (efferent)- control effector organs and are primarily located in the CNS
-sensory (afferent)- receive sensory info and cell body is located in CNS or ganglia
-projection- connect different regions far away and are located in the CNS
-interneurons- create circuits by connecting neurons and are in the CNS or ganglia

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9
Q

types of supporting cells

A

astrocytes and satellite cells

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10
Q

astrocytes

A

-supporting cells of the CNS
-star-shaped
-end feet contact capillaries (they interact with blood vessels)
-provide structural support

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11
Q

satellite cells

A

-supporting cells of the PNS
-surround cell bodies in ganglia
-support and protect neurons

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12
Q

two types of myelinating cells

A

oligodendrocytes and schwann cells

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13
Q

oligodendrocytes

A

-located in the CNS
-form and maintain myelin that wrap around axons
-interact with several neurons

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14
Q

schwann cells

A

-located in the PNS
-wrap myelin around axons
-only surround one neuron

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15
Q

microglia

A

-guard and protect the CNS
-respond to sites of damage or injury
-phagocytose dying cells or debri
-immune surveillance
-only located in the CNS

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16
Q

ependymal cells

A

-cuboidal or columnar epithelial cells
-form a simple layer that line ventricles and central canal of spinal cord
-produce CSF
-cilia help circulate CSF

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17
Q

cerebrum

A

-largest part of the brain
-comprised of white and gray matter
-consists of lobes
-divided into two halves

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18
Q

common cell types of cerebrum

A

-neurons
-neuroglial cells- astrocytes, oligodendrocytes, and microglia

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19
Q

what neurons make up the gray matter?

A

-pyramidal cells
-fusiform cells
-cells of martinotti
-horizontal cells of cajal
-stellate cells

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20
Q

cerebellum

A

-cerebellar cortex (gray matter) with a white matter core
-divided into two halves
-cortex contains 3 layers: molecular layer (outer), purkinje cell layer, and granular layer (inner)

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21
Q

function of cerebellum

A

-maintain balance and equilibrium
-little brain
-controls posture changes
-coordinates voluntary muscle movements- fine and smooth movements
-cognitive functions like attention, language, and memory

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22
Q

what are the common cell types of cerebellum?

A

-neurons in the cortex
-neuroglial cells- astrocytes, oligodendrocytes, and microglia in the cortex and white matter

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23
Q

where are unipolar brush cells found?

A

primarily in flocculonodular lobe and vermis

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24
Q

what types of cells are inhibitory neurons?

A

-stellate cells
-basket cells
-purkinje cells
-golgi cells

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25
Q

what types of cells are excitatory neurons?

A

-granule cells
-unipolar brush cells

26
Q

spinal cord

A

-thick column of nerves within vertebrae that extend from the brainstem to the lumbar spinal region
-helps communicate info from the PNS to the brain
-31 pairs of spinal nerves radiate from spinal cord: 8 cervical nerves, 12 thoracic nerves, 5 lumbar nerves, 5 sacral nerves, and 1 coccygeal nerve

27
Q

gray matter

A

-mainly comprised of neuronal cell bodies and dendrites
-found in center of spinal cord and in layers of cerebral cortex
-processes info

28
Q

white matter

A

-features both myelinated and unmyelinated axons
-has very little neuronal cell bodies
-found surrounding gray matter of spinal cord and inside brain
-transmits info

29
Q

anatomy of a neuron

A

comprised of dendrites, cell body, and axons

30
Q

dendrites

A

-receive and integrate incoming signals
-highly branched
-dendritic spines —> dynamic structures, believed to be involved in learning and memory

31
Q

cell body

A

-aka soma or perikaryon
-metabolic and synthetic machinery
-rough endoplasmic reticulum
-round, oval, or triangular (pyramidal)
-large range in size of 5-100 um

32
Q

axon

A

-aka nerve fibers
-transmits signals like APs
-constant diameter, usually unbranched
-contains axon hillock which is the site for AP initiation

33
Q

action potentials

A

if depolarization reaches threshold potential then:
-voltage gated Na channels will open
-explosive propagation of depolarization
-Na channels inactivate
-delayed K channels open, efflux of K repolarizes the cell
-hyperpolarization and refractory period

34
Q

myelination

A

-rich in lipids, which give the white matter appearance
-glial cells perform myelination —> in CNS, oligodendrocytes cover the axons and in the PNS, schwann cells cover only part of an axon
-concentric layers of plasma membrane that fuse together and remove cytoplasm

35
Q

initiation of myelination in the CNS

A

-oligodendrocyte progenitor cells (OPCs) differentiate into mature oligodendrocytes
-send limb-like extensions from the cell body —> myelinate multiple nearby axons (up to 50 each)
-nodes of ranvier are unmyelinated regions of the axon

36
Q

what does myelin do for AP transmission?

A

-myelin increases conduction speed —> lipids are poor conductors and great insulators
-enables saltatory conduction where the AP jumps between nodes of ranvier

37
Q

do myelin sheath diameters affect AP speed?

A

yes, the larger diameters increase the conduction velocity of the AP

38
Q

synapse

A

-region between cells and dendrites where electrical or chemical signals are passed
-comprised of three parts: pre-synaptic terminal which contains synaptic vesicles that fuse with the pre-synaptic membrane and release their contents into the synaptic cleft —> bind to receptors on the post-synaptic membrane

39
Q

neuromuscular junctions (nmjs)

A

connect nerves to muscles

40
Q

what happens at an NMJ?

A

motor neuron connects to muscle —> AP in neuron causes the voltage-gated Ca channels to open and the influx of Ca causes the synaptic vessels containing Acetylcholine to fuse with the pre-synaptic membrane with the help of proteins —> once Acetylcholine is in the synaptic cleft, it binds to the ligand-gated Na channels on the motor end plate

41
Q

what happens after Ach binds to the Na channels?

A

influx of Na causes AP that triggers the T tubules to connect with the SR which releases Ca —> Ca binds to the troponin complex, causing a conformational change in the myosin-binding sites —> these sites open for myosin to bind with actin and cause the muscle to contract

42
Q

what happens during muscle relaxation?

A

Ca is resorbed and the myosin-binding sites close

43
Q

post-synaptic membrane effects

A

-activation of receptors: voltage-gated ion channels with local, immediate effect, ligand-gated io channels with local, immediate effect, and g-protein coupled receptors with more widespread effect
-depolarization
-hyperpolarization

44
Q

excitatory postsynaptic potential (EPSP)

A

positively charged ions flow into neuron —> depolarization —> more likely to fire an AP

45
Q

inhibitory postsynaptic potential (IPSP)

A

negatively charged ions flow into neuron —> hyperpolarization —> less likely to fire an AP

46
Q

glutamate

A

-AP fires and glutamate is released from presynaptic neuron
-binds ligand-gated ion channel NMDA-R and also needs glycine as a co-agonist
-Na and Ca floods into the postsynaptic neuron
-Ca is a secondary messenger and activates kinases
-neuron becomes depolarized
-high levels of glutamate —> seizures

47
Q

GABA

A

-AP fires —> GABA is released from presynaptic neuron
-GABA binds ligand-gated ion channel GABAa-R
-Cl floods into postsynaptic neuron
-neuron becomes hyperpolarized
-low GABA levels —> seizures

48
Q

myasthenia gravis (MG)

A

-neuromuscular junction disorder
-autoimmune attack on acetylcholine receptors which disrupts neuromuscular transmission

49
Q

amyotrophic lateral sclerosis (ALS)

A

-neurodegenerative disorder related to motor neurons
-progressive degeneration of motor neurons impairs muscle control

50
Q

alzheimer’s dementia

A

-neurodegenerative disorder related to cognitive function
-accumulation of amyloid plaques and tau tangles disrupts cognitive functions

51
Q

what are the causes of MG?

A

production of abnormal antibodies against Acetylcholine receptors, overactive compartment pathway, and disruptions of the thymus

52
Q

what are symptoms of MG?

A

muscle weakness and tiredness

53
Q

histopathology of MG for muscle fibers

A

normal muscle fibers: striated and uniform
MG muscle fibers: different sized cells and more nuclei and less uniform in appearance

54
Q

histopathology of MG for NMJ

A

normal NMJ: has multiple junctional folds
MG NMJ: less junctional folds that are wider and increase the synaptic cleft

55
Q

what are the causes of ALS?

A

largely unknown but 5-10% of the cases are genetic

56
Q

what are the symptoms of ALS?

A

eye movement abnormalities, progressive weakness, clumsiness, slurred speech, trouble doing daily activities, cognitive, and behavioral impairment

57
Q

histopathology of ALS

A

-less gray matter in the sALS group
-loss of myelination and motor neurons in the lateral spinal column

58
Q

dementia

A

an umbrella term used to describe a group of symptoms that affect cognitive abilities, memory, thinking, and behavior

59
Q

alzheimer’s dementia

A

disease that is the most common cause of dementia, up to 60-70% of dementia cases

60
Q

what are the causes of alzheimer’s dementia?

A

largely unknown but a combination of age-related changes in brain, genetic, environmental, and lifestyle factors can contribute —> genetic alterations of APP, PSEN1, PSEN2

61
Q

what are the symptoms of alzheimer’s dementia?

A

memory loss, cognitive difficulties, wandering, personality/behavior changes, problems recognizing friends and family, loss of bodily functions like talking, walking, and swallowing

62
Q

pathology of alzheimer’s dementia

A

-amyloid plaques- abnormal buildup and clumps of beta-amyloid (AB) protein fragments between neurons
-neurofibrillary tangles- twisted strands of tau fibers inside neurons
-loss of neurons- loss of function and connection to other neurons and die
-brain atrophy- brain tissues shrink

Human Body_TP (7 decks)

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