Lecture 1 Flashcards
(147 cards)
1
Q
What is the enteric nervous system?
A
nervous system that surrounds digestive tract
1
Q
What information has direct communication to the brain?
A
special senses –> cranial nerve
2
Q
What information goes through the spinal cord first?
A
somatic sensory, non-cranial
3
Q
What is somatic sensory, non-cranial communicated through?
A
spinal nerves
4
Q
What are special senses?
A
hearing, equilibrium, sight, smell, taste
5
Q
Where does communication go directly from the brain?
A
somatic motor, cranial: cranial skeletal muscles –> cranial nerves
visceral motor: parasympathetic nervous system –> cranial nerves
6
Q
What information goes from brain to spinal cord and then out?
A
somatic motor, non-cranial (non-cranial skeletal muscles) –> spinal nerves
visceral motor, ANS (all SNS & sacral PaNS) –> spinal nerves
7
Q
What is white matter?
A
collections of myelinated axons in the central nervous system
8
Q
What is myelin?
A
multi-layer lipid coat that ‘insulates’ axons - formed by specialized glial cells in the PSN and CNS
9
Q
T/F: Although both the PNS and CNS have myelinated axons, only the PNS has white matter
A
False, Only CNS has white matter
10
Q
What does myelin increase?
A
velocity signal transmission along an axon
11
Q
What is gray matter?
A
areas of CNS that have relatively few myelinated axons
12
Q
What is gray matter mostly comprised of?
A
neuronal & glial cell bodies
13
Q
What helps myelin made of that helps conduction?
A
fat
14
Q
What is a tract?
A
collection of axons in the CNS
15
Q
What are large tracts usually?
A
white matter
16
Q
What is a nerve?
A
collection of axons in the PNS
17
Q
The longer an axon is, the more __ the information it carries –> more likely it will be __
A
crucial; myelinated
18
Q
How do dendrites connect with other neurons?
A
via synapses
19
Q
What are dendrites?
A
the receivers
20
Q
inputs from other neurons are __ –> __ is made based on inputs regarding whether the neuron will send a signal.
A
integrated; decision
21
Q
What are the sites of integration?
A
axon hillick
22
Q
Where does the neuron send a signal down?
A
the axon
23
Q
Much of the volume of the cerebral cortex is __ matter
A
white
24
Gray matter forms a relatively __ layer superficially
thin
25
Axons/nerve in the __ can sometimes regenerate after damage.
PNS
26
T/F: The CNS is much less isolated than the CNS
False, PNS is less isolated
27
Are there fewer neuronal bodies in the PNS or CNS?
PNS
28
ctions of neuronal cell bodies in the peripheral nervous system
ganglia
29
collections of neuronal cell bodies in the central nervous system
nuclei
30
Basal nuclei are often known as?
basal ganglia
31
Both nuclei and ganglia will contain axons, but more of the volume of these structures is devoted to?
neuronal and glial cell bodies
31
32
What protects the CNS?
blood brain barrier
33
How are nuclei grouped?
by criteria:
- same anatomical area
- same function
34
What are 3 glial cell types?
Astrocytes
Oligodendrocytes
Microglia
35
What are fluid spaces within the CNS?
Ventricles, ependymal cells, choroid plexus
Interstitial fluid
36
What are functions of the astrocyte?
forms part of BBB
regulates interstitial fluid composition
provides structural support & organization to the CNS
assists w/ neuronal development
replicated to occupy space of dying neurons
37
What are functions of the oligodendrocytes?
myelinates & insulates CNS axons
allows faster action potential propagation along axons in the CNS
38
What are functions of microglial cells?
phagocytic cells that move through CNS
protects CNS by engulfing infectious agents & other
potential harmful substances
fight pathogens
If the pathogen cannot be eliminated by resident microglia, they “call in” other white blood cells through secretion of soluble factors (cytokines) and can present antigen to other immune cells
39
What are functions of ependymal cells?
lines ventricles of brain & central canal of spinal cord
assists in production and circulation of CSF
40
What has the numerous cells in the CNS?
astrocytes
41
Where are astrocytes highest in number?
gray matter
42
What role do astrocytes have in the CNS?
- Facilitate the formation and strengthening of synapses (neuroplasticity)
- Regulate the concentration of ions in the interstitial fluid (K+, Na+, Cl-, HCO3-, Ca+2)
- Structural support for the brain
Intermediate filament - GFAP (glial fibrillary acidic protein)
- Barrier functions – induce the formation of the BBB at the brain microvasculature, form a “limiting membrane” at the external CNS surface
- “Feed” neurons – help extract nutrients from the blood, provide nutrients to neurons to support energy metabolism
43
How are astrocytes connected to each other?
via gap junctions
44
Small “tunnels” that connect the intracellular fluid of astrocytes to each other (span the cell membranes and connect cell to cell) in a network are known as?
syncytium
45
What is myelin sheath?
compacted layers of cell membrane rich in sphingolipids that have very little cytosol
46
Each process wraps around the axon of a CNS neuron many times, “sheathing” the axon in myelin
oligodendrocytes
47
What is the function of myeline?
Increases the speed with which an action potential moves down an axon
Reduces the energy consumed by movement of an action potential down an axon – more efficient signaling
48
What are microglial cells derived from?
blood-borne immune cells (monocytes) that migrate into CNS
49
What is the space around the periphery of the brain called?
subarachnoid space
50
How many ventricles are within particular compartments of the brain?
4
51
Where is CSF?
Within the subarachnoid space and central canal of the spinal cord
52
CSF is a specialized fluid formed from the?
choroid plexus
53
What is the choroid plexus?
complex of capillaries and epithelial cells
54
Where is the choroid plexus?
Mostly located in the lateral ventricles
55
What is the production and circulation of CSF?
Produced in the floor of the lateral ventricle by the choroid plexus
Moves from the lateral ventricles --> 3rd ventricle --> 4th ventricle
Circulates into the subarachnoid space and down the spinal cord
Eventually absorbed by specialized structures known as arachnoid granulations
56
What absorbs CSF?
arachnoid granulations
57
What do arachnoid granulations do?
transport CSF fluid into venous structures
58
Ependymal cells that line the ventricles are __
ciliated
59
What are tight junctions around choroid plexus meant to prevent?
unwanted substances from entering CSF
60
What Selectively transports water, electrolytes, nutrients from blood to CSF?
choroid plexus
61
The interstitial fluid (extracellular fluid) of the brain and spinal cord is formed by?
Filtration of CSF from the ventricles through the ependymal cells
Regulated filtration of fluid through capillaries deeper in the CNS tissue
62
What does the BBB keep out?
immune cells
noxious wastes and toxins
pathogens
63
Astrocytes contact capillaries in the CSF via structures known as?
endfeet
64
What do endfeet cause?
increased tight junction expression in capillary endothelial cells
65
What to endfeet tell capillaries?
to transport into the CNS tissue
- Cause endothelial cells to express transport proteins for desirable molecules and inhibit expression of pro-inflammatory signals
66
What is the BB made up of?
astrocytes & capillaries
67
What is in the PNS?
Nerve and ganglion structure
Nature of the Blood-Nerve Barrier (BNB)
Glial cell types:
- Schwann Cells
- Satellite cells
68
What composes a nerve?
epineurium
perineurium
endoneurium
69
What is the epinderium?
strong, fibrous connective tissue covering that surrounds each nerve
Blood vessels run within this layer
70
What are blood vessels call that run in the epinerium?
vasa nervorum
71
What is endonerium?
delicate connective tissue layer that surrounds individual axons
72
What is the perineurium?
surrounds bundles of axons (some myelinated, some not) known as fascicles
73
What are the perineurium formed by?
fibroblast-like cells arranged in sheets 2-6 cells thick
74
Tight junctions are found between perinerium, what does this allow?
therefore the perineural layer can regulate what moves into the fascicle
75
What are the layers of a nerve from innermost to outermost?
perineurium
epineurium
76
What is barrier 1 of the BNB?
the cells of the perineurium and the tight junctions between them
77
What is barrier 2 of the BNB?
the endothelial cells that line the capillaries within the fascicles also express many tight junctions
78
What do both barriers of the BNB do?
actively regulate the movement of ions and immune cells into the fascicles
79
BBB is much more permissive to the entrance of white blood cells (leukocytes) than the BNB
False, BNB than BBB
80
Why may we relate the ability of peripheral nerves to regenerate after being severed?
because of the permissive BNB
81
What do schwann cells do?
provide the myelin sheath for axons within fascicles
82
How are schwann cells differ from oligodendrocytes?
that one cell only myelinate one axon
83
What do satellite cells do?
surround, protect, and nourish neuronal cell bodies
84
Where are satellite located?
in ganglia
85
Multiple satellite cells are closely apposed to neuronal cell bodies with roles in?
nutritional and ionic homeostasis
86
What are key components of neurons?
Dendrites, dendritic spines, and synapses
Structures of the soma
The axon, axon hillock, and synaptic terminals
Axonal transport
87
Dendrites are the “__” area of the neuron
input
88
What do dendrites connect to?
soma of neuron
89
Why are the spines of dendrites close to axon terminal?
to form synapses
90
More “effective” dendritic spines are ones that carry more information to? What do they look like?
rest of neuron
tend to be larger, broader, and “mushroom-shaped”
91
T/F: axons in the PNS have multiple schwann cells
True
92
Spine maturation of the dendrites make what more effective?
synapse
93
Which spines are shown to elicit more effective neuronal responses when they are stimulated?
mushroom
branched
94
Which dendritic spine is immature & looking for a connection w/ an axon terminal?
filopodia
95
Where is the site of protein synthesis for the rest of the nruon?
soma
96
What is nissl substance/bodies?
basophilic area nearby the nucleus composed of lots of free ribosomes and rER
97
What are found in the soma?
Microtubules, actin microfilaments, and neurofilaments
98
What are neurofilaments?
intermediate filaments that are more concentrated in axons
99
what do neurofilaments do?
provide structural stability for neuronal processes
100
What does microtubules having opposite orientation in dendrites vs. axons do?
Ensures that dendritic and axonal components are directed to the right places
101
The axon, axon hillock, and synaptic terminals are the sites of?
unique electrical phenomenon of the cell membrane known as an action potential
102
T/F: Axons can be myelinated by Schwann cells (PNS) or oligodendrocytes (CNS)
True
103
What are nodes of Ranvier?
myelin-free segments that separate myelin sheaths
104
What are nodes of Ranvier cruical for?
action potential generation
105
What is the morphology of pseudo-unipolar neurons?
These neurons have a distal process that either interacts with a sensory receptor or serves as a sensory receptor (A)
The proximal process synapses in the CNS (B)
process that connects A to B behaves as axon
106
What is an example of pseudo-unipolar neurons ?
dorsal root ganglion cells
107
What is the morphology of bipolar neurons?
These neurons have a distal process (A) that acts as a dendrite – it either serves as a sensory receptor or interacts with a sensory receptor
The proximal process synapses in the CNS – it is an axon and conducts action potentials (B)
108
Where do we see bipolar neurons?
Typical of neurons that detect the special senses – vision, hearing, smell
109
Where do we see pdeudo-unipolar neurons?
somatic sense
110
What is the most common neuron?
multipolar
111
What is this an example of?
multipolar neuron
112
How do multipolar neurons recieve information?
from other neurons via synaptic terminals
113
What does the cell body of a multipolar neuron do?
summates and integrates this information
114
What does the axon of the multipolar neuron do?
carries action potentials to:
Other neurons
Glands
Muscle tissue
115
Multipolar neurons are typical of all?
interneurons & somatic motor neurons
116
What is the afferent pathway?
nerves that carry (sensory) information to the central nervous system
117
What are cranial nerve afferents?
Special Senses
- CN I, II, VII, VIII, IX, X
Somatic Senses
- Mostly CN V
Visceral Sensory
- CN IX and X
- Baroreceptors
- Visceral sensation from most of the alimentary tract, lungs, heart
118
Sensation is composed of a number of distinct steps (not all need to be present):
- Detection of a physical/chemical stimulus by some type of receptor
- Transduction
- Other neurons at various levels of the central nervous system can detect the electrical impulse and modify its intensity and route the signal to various CNS locations
- Perception
119
What is transduction?
transforming the physical stimulus into an electrical impulse that can be carried along an axon
120
What is perception?
conscious awareness of the sensation – this occurs at the level of the cortex
121
What sensory afferent information is not percieved?
osmolarity, blood pressure etc.
122
What influences perception?
neurons modifying the intensity
123
What are afferent that ascend through the spinal cord?
Somatic sensation below the neck
-Skin receptors – pain, temperature, fine and coarse touch, vibration
- Joint and intra-muscular receptors – golgi tendon organs, muscle spindles, joint receptors --> proprioception
Visceral sensation
- Distal portions of the colon
- Bladder
- Reproductive organs
124
When does a motor response occur?
after sensory input is integrated usually by circuits involving multiple neurons
125
What is a motor system?
a motor neuron synapses with some sort of effector so that it can activate it when the neuron is excited
126
What is excitation/action potential?
multiple electrical signals travelling down the axon
127
Skeletal muscle (voluntary movements)
Smooth muscle (blood vessels, GI tract, genitourinary tract, respiratory tract)
Glands (endocrine or exocrine)
are examples of?
effectors
128
What is efferent?
neurons that carry information from the CNS to the peripheral nervous system
129
What is somatic motor efferents?
control of skeletal muscles
- Usually voluntary
- Some we don’t have conscious control over (i.e. middle ear muscles)
130
What are major cranial nerves, somatic motor?
CN VII, V, XI: movement of face, muscles of mastication, shrugging
CN IX, X, XII: tongue/swallowing
CN III, IV, VI: muscles of eyes
131
Efferents for skeletal muscles below the neck are part of the?
corticospinal tract
132
What is the pathway of the corticospinal tract?
Axons from neurons in the pre-central gyrus decussate and descend down the spinal cord --> Synapse on anterior horn motor neuron --> Axon of anterior horn motor neuron exits the central nervous system as a spinal nerve
133
What are visceral motor efferents - cranial nerve PaNS?
- CN X – PaNS control for the heart, lungs, majority of the GI system
- CN III – PaNS control over pupillary muscles
- CN VII, IX – PaNS control over salivary, tear glands
134
What are visceral motor efferents - spinal nerve ANS & PaNS?
- SNS control for the heart, lungs, proximal GI tract
- SNS control for pupillary muscles, salivary glands, tear glands
- SNS and PaNS control for distal GI tract, reproductive structures, bladder
135
What are components of the ANS?
- SNS
- PaNS
- ENS
136
What is the SNS?
- fight or flight
137
What happens during fight or flight?
Increases heart rate and cardiac output
Improves ventilation
Decreases digestive function
Increases glucose availability (gluconeogenesis, glycogenolysis)
Increases blood flow to skeletal muscles, heart
Decreases blood flow to GI tract, skin, kidneys
Major hormones/neurotransmitters: epinephrine and norepinephrine
138
Where is paravertebral ganglia in the SNS?
adjacent to the vertebral column
139
Where are prevertebral ganglia in the SNS?
Anterior to vertebral column
140
What is the PaNS?
rest and digest
141
What happens during rest and digest?
Decreases heart rate and cardiac output
Bronchoconstriction and increased mucous secretion
Increases digestive function and GI motility
Increases blood flow to digestive tract
Major neurotransmitter: acetylcholine
142
What are the two main pathways of the PaNS?
vagus nerve
sacral nerves
143
What does the vagus nerve innervates?
all of the visceral efferents up to the proximal large bowel
144
What do the sacral nerves innervate?
all of the visceral efferents to the rest of the large bowel, kidney, reproductive organs
145
Where are ganglia located in the PaNS?
located closer to target organs
