TEST 1 REVIEW Flashcards
1
Q
afferent
A
from receptor to brain
2
Q
efferent
A
from brain to organ
3
Q
Peripheral nervous system maintains homeostasis through
A
dual innervation, antagonistic action between parasympathetic and sympathetic nervous systems
4
Q
purkinje neuron
A
major output neuron of the cerebellum
5
Q
Astrocytes
A
glial cells – involved in blood brain barrier maintenance by enveloping endothelial capillaries, development of new circuits, repair, release gliotransmitters, and tripartite system of connection
6
Q
where are action potentials generated
A
axon hillock
7
Q
the four functional neural zones
A
reception, integration, conduction, transmission
8
Q
location of signal reception
A
dendrites and cell body
9
Q
location of signal integration
A
axon hillock
10
Q
location of signal conduction
A
AP travelling down axon
11
Q
location of signal transmission
A
release of NT at axon terminals
12
Q
differences between axons and dendrites
A
Axons do not branch dendrites taper as well as branch, dendrites have spines and axons are smooth
13
Q
depolarization
A
membrane becomes less negative
14
Q
repolarization
A
membrane returns to resting value
15
Q
hyperpolarization
A
membrane becomes more negative
16
Q
equilibrium potential
A
potential at which an ion is at equilibrium across the membrane i.e. there is no net movement of that ion across the membrane, calculated using the Nernst equation
17
Q
goldman equation
A
weighted average of equilibrium potentials for all ions with permeability to that cell
18
Q
electrotonic current spread
A
charge spreads through cytoplasm causing changes in adjacent membrane potential, no contribution from VG channels, primarily ligand gated
19
Q
Characteristics of APs
A
Triggered by net graded potential reaching threshold potential at axon hillock, Caused by opening and closing of ion gated channels, Do not degrade over time, travel long distances, All or none size, duration, and shape which are the same in a given neuron but not necessarily among a population of neurons, Occur IN axons, Self propagating, Electrotonic spread, Have a regenerative cycle
20
Q
Channel activity in an AP
A
o VG Na channel opens in depolarization
o VG K channels open more slowly in repolarization
o VG Na channels close and K channels close more slowly in hyperpolarization
21
Q
Hodgkin cycle
A
a positive feedback loop that drives depolarization – opening of Na channels causes influx of Na causing further depolarization and more Na channels to open
22
Q
VG Na channels at rest
A
activation gate closed
23
Q
VG Na channels during depolarization
A
activation gate open
24
Q
VG Na channels during repolarization
A
inactivation gate closed, activation gate open
25
Saltatory conduction
APs leap from node to node, does not degrade like regular electrotonic current spread because APs are regenerated at nodes – the alternating of electrotonic conduction with new APs along the axon
26
cause of absolute refractory period
closure of inactivation gate of Na channels during hyperpolarization
27
Factors that lower intracellular Ca
o Binding with intracellular buffers
| o Ca ATPases
28
[Ca] at high frequency APs
Ca influx is greater than removal, ↑ [Ca], many synaptic vesicles release their contents, high [neurotransmitter] in synapse
29
Electrochemical driving force
|Vm – Eion|
30
Cholinergic transmission
acetyl CoA (from mitochondria) + choline >>choline acetyl transferase >> Ach, released by exocytosis, broken down by AchE in synapse, choline re-entered by presynaptic cell while acetate diffuses out of the synapse
31
Electrical synapse
gap junction - allows movement of small molecules/ions without having to cross membrane
32
gap junction
Made with 1 hemmichannel/cell, connexon formed of 6 connexins
33
Chemical synapse
chemical messenger crosses synaptic cleft – increases diversity of signals that can be passed through the synaptic cleft
34
PNS chemical synapses
axon terminals, varicosities
35
CNS chemical synapses
En passant synapse, spine synapse
36
Characteristics of NTs
o Synthesized in neurons
o Released at presynaptic cell following depolarization
o Bind to postsynaptic receptor and cause a detectable effect
o Mechanism of inactivation
37
Types of NTs
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o Amino acids
o Neuropeptides
o Biogenic amines
o Acetylcholine
o Miscellaneous (gases, purines)
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38
Inhibitory NTs
cause hyperpolarization of postsynaptic cells (IPSP), make cell less likely to generate AP
39
Excitatory NTs
cause depolarization of membrane (EPSP), make cell more likely to generate AP
40
Ionotropic receptors
ligand gated ion channels, fast e.g. nicotinic Ach receptors
41
Metabotropic receptors
changes shape, formation of second messenger, alters opening of ion channel, slow, leads to long term changes via second messengers
42
Nicotinic receptor
always excitatory, ionotropic, 5 subunits, Na, Ca in
43
Muscarinic receptor
metabotropic, g-protein coupled, 7TM subunits, activates cAMP (PKA)
44
Biogenic amines
serotonin and the catecholamines
45
catecholamines
tyrosine derived - NE, E, dopamine
46
Synaptic facilitation
repeated AP results in increased Ca released in axon terminal, increased NT released
47
Synaptic depression
repeated APs decrease NT release, progressive depletion of readily releasable pool
48
Post-tetanic potentiation
train of high frequency APs leads to increased NT release, believed to involve Ca dependent increase in NT containing vesicles in axon terminal which might lead to recruitment of vesicles from reserve pool
49
Alzheimer’s treatment
AchE inhibitors; found reduced level of Ach in the brain of alzheimers patients, wanted to increase Ach in brain to help that, but problem is Ach deficiency is symptom, problem is the plaques that cause NT reduction
50
Depression treatment
Prozac – selective serotonin reuptake inhibitor, treats symptom not cause
51
Generator potential
sensory receptor IS the primary afferent neuron
52
Receptor potential
sensory receptor is separate from the primary afferent neuron – requires an NT from receptor to afferent neuron creating a graded potential that triggers an AP
53
Telereceptors
detect distant stimuli
54
Exteroreceptors
detect stimuli on outside of body
55
Interoreceptors
stimuli inside the body
56
Stimulus modality
what type of energy the stimulus responds to
57
Adequate stimulus
preferred stimulus modality
58
ampullae of lorenzini
detect pressure, temperature, electrical fields at end of canal at the base of which lies gel that is in constant contact with water – receptor potentials
59
Theory of labeled lines
discrete pathway from the sensory cell to the integrating centre
60
Lateral inhibition
signals from neurons at the centre of a receptive field inhibit neurons on the periphery – to determine locations of stimuli
61
Dynamic range
range of stimulus intensities over which a receptor can increase its response
62
threshold of detection
response 50% of the time in one receptor
63
large dynamic range
large change in stimulus causes a small change in firing frequency – poor sensory discrimination
64
narrow dynamic range
small change in stimulus causes a large change in AP frequency – good sensory discrimination
65
range fractionation
groups of receptors work together to increase dynamic range without decreasing sensory discrimination
66
Weber-fechner law
resolution of perception diminishes for stimuli of greater magnitude
67
Phasic receptors
produce APs at the beginning and/or end of the stimulus, encode change in stimulus but not stimulus duration
68
Tonic receptors
produce APs as long as the stimulus continues, encode stimulus duration
69
olfactory receptor cells
are ciliated bipolar neurons with odorant receptor proteins in cilia
70
odorant receptor protein
Each olfactory neuron expresses one, but receptors can recognize more than one odorant
71
odorant response
Odorant binds receptor causing conformational change, Golf activates adenylate cyclase increasing cAMP, which opens cAMP gated ion channels causing Ca and Na to enter cell – generator potential – Ca activates Cl (out) channels increasing depolarization, generator potential opens VG Na channels – AP
72
Vomeronasal organ
detects pheromones – structurally and molecularly distinct from the olfactory epithelium, connected to oral or nasal cavity, GPCR activates PLC system which opens ion channels causing depolarization
73
Invertebrate olfactory system
located in many parts of the body but mainly on antennae in arthropods
74
Sensilla
hair like projections of cuticle, contain odorant bipolar neurons which have GPCRs that cause cAMP formation, opening of ion channels and depolarization
75
Taste receptor cells
epithelial cells release NTs and express more than one kind of receptor protein, a single primary afferent taste neuron may synapse with more than one receptor cell with diverse signal transduction mechanisms
76
salty taste transduction mechanism
Na ions depolarize receptor cell membrane through open ion channels
77
sour taste transduction mechanism
protons enter through channel and block K channel leading to depolarization
78
sweet, bitter, umami taste transduction mechanisms
activation of PLC, PIP, IP3, causing release of Ca into cytoplasm from ER that opens Na channels causing depolarization and NT release
79
Invertebrate taste
located on sensilla inside and outside mouth, on legs, and wing margin, bipolar sensory neurons that express only one receptor protein (each), more similar to vertebrate olfactory neurons
80
Mechanoreceptors
linked to ECM and alter channel permeability
81
ENaC
epithelial sodium channels
82
TRP channels
transient receptor potential channels (allow K and Ca to cross)
83
Vertebrate tactile receptors
widely dispersed in skin, isolated, free nerve endings maybe wrapped in accessory structure
84
Pacinian corpuscle
free nerve ending with 60-70 layers of membranes with gel in between, pressure and vibration, transient depolarization at onset and offset of stimulus
85
Merkel’s disk
free nerve endings associated with an enlarged epidermal cell with small receptive fields, slowly adapting tonic receptors – most sensitive to indentation
86
Root hair plexus
free nerve endings wrapped around basis of hair follicles, rapidly adapting phasic receptors, sensitive to changes in movement
87
Trichoid receptor
hairlike projection of cuticle, bipolar sensory neuron, TRP channel, also used in olfaction and gustation
88
Campaniform receptor
dome shaped bulge od cuticle, sense deformation of cuticle as it moves, bipolar sensory neuron, used in proprioception
89
Muscle spindles
monitor muscle length (skeletal)
90
Golgi tendon organs
monitor muscle tension
91
Joint capsule receptors
located in capsules that enclose joints, monitor pressure, tension, and movement
92
Statocysts
organ of equilibrium in aquatic invertebrates, hollow fluid filled cavities lined with mechanosensory neurons, Contain statoliths
93
statoliths
dense particles of calcium carbonate, their movement stimulates mechanoreceptors
94
Vertebrate hair cells
modified epithelial cells NOT neurons with cilia on apical surface all connected by tip links
95
kinocilium
one true cilium on each hair cell
96
stereocilia
microvilli made of actin bundles 20-300 on each, pivot along base in response to movement, oriented according to size
97
stereocilia moving away from kinocilium
blocks K channel opening and NT release so there is no AP generation in primary afferent neuron
98
stereocilia moving towards kinocilium
opens K channels and causes NT release for AP generation in PAN
99
endolymph
fluid bathing apical side that is high in K, concentration is actively maintained in vestibular apparatus and cochlea, high K low Na
100
perilymph
fluid bathing basal side, similar to CSF, high Na low K, fills cochlear ducts
101
Vestibular apparatus
3 semicircular canals with ampulla at one end and 2 sac like swellings of utricle and saccule, lagena is extension of saccule that in birds and mammals becomes cochlear duct or cochlea
102
macula
in utricle and saccule, mineralized otoliths in gelatinous matrix that have hair cell cilia embedded, detect linear acceleration and tilting of head when inertial force causes hair bundle movement
103
crista
in ampullae of semicircular canals – has gelatinous matrix in cupula that DOES NOT have otoliths but does have stereocilia embedded, detect angular acceleration by inertial force of fluid movement causing hair bundle movement - pressure of endolymph in opposite direction of movement
104
Push-pull system
one canal is stimulated, partner on other side is inhibited, direction of movement determined by comparing contralateral canals
105
cochlea
coiled in mammals, contains organ of corti
106
organ of corti
has hair cells on basilar membrane, inner rows of sensory receptors and stereocilia embedded in tectorial membrane
107
Sound transduction
vibrations to oval window, pressure waves in perilymph of vestibular duct, basilar membrane vibrates, stereocilia bend, opens TRP channels, K in for depolarization, hair cells release glutamate which excites afferent neuron, round window dissipates energy
108
sound frequency detection
basilar membrane is stiff and narrow at proximal end and flexible and wide at distal end, high frequency at proximal end
109
sound location detection
brain uses time lags and differences in intensity to detect location, head rotation localizes sound
110
ciliary photoreceptor cells
have a single highly folded cilium that forms disks containing photopigments
111
rhabdomeric photoreceptor cells
have microvillar projections that contain photopigments – outfoldings of apical surface
112
Vertebrate photoreceptors
ciliary – rods (dim) and cones (bright), have inner segment which forms synapses with other cells and outer segment with photopigments
113
Chromophore
pigment derived from vitamin A (e.g. retinal) that has C=C bonds, when light is absorbed bond changes cis to trans
114
Photoreceptor protein
e.g. opsin GPCR – structure determines photopigment sensitivity
115
Rhabdomeric phototransduction
o Chromophore absorbs energy from photon and changes conformation (isomerizes cis-trans)
o Activated chromophore dissociates from opsin – bleaching
o Opsin activates g-protein which activates PLC, converting PIP to DAG and IP3, DAG activates a TRP channel, Ca and Na enter and depolarize cell
116
ciliary phototransduction
o Chromophore absorbs energy from photon and changes conformation (isomerizes cis-trans)
o Activated chromophore dissociates from opsin – bleaching
o Opsin activates Gi called transducin, which activates PDE which converts cGMP to GMP, decreased [cGMP] closes Na channel, decreasing [Na] hyperpolarizes cell
117
flat sheet eyes
some sense of light direction/intensity, larval eyes or accessory adult eyes, no image formation
118
cup shaped eyes
retinal sheet is folded into narrow aperture that allows discrimination of light direction and intensity, light/dark
119
camera eyes
most vertebrates, lens in aperture improves clarity and intensity by refracting light and focusing it on one point on retina
120
compound eyes
found in annelids, molluscs, arthropods – convex retina, detection of movement and wide field of view
121
composition of compound eyes
Composed of ommatidia – the photoreceptor – forms images by each ommatidia operating independently and forming part of an image that the neurons interconnect, OR, ommatidia work together to form image
122
limitations of compound eyes
size limited by wave properties of light, number of ommatidia limited by size - resolving power can be increased by reducing size or increasing number of ommatidia
123
3 layers of vertebrate vesicular eye
sclera, uvea, retina
124
sclera
white of eye, support and protection, has cornea – anterior modification
125
uvea
choroid, ciliary body, iris – for nutrition gas exchange and reducing reflection, tapetum in nocturnal animals as reflective modification
126
retina
lines inside of choroid, light sensitive
127
aqueous humor
fluid in anterior chamber
128
iris
pigmented smooth muscle regulating size of pupil
129
ciliary body
muscles that change lens shape
130
lens
behind iris, focus images on retina
131
vitreous humor
gelatinous mass in posterior chamber
132
layers of cells in vertebrate vesicular eye
ganglion cells, amacrine, bipolar, horizontal, rods/cones – axons of ganlions exit retina at optic disk
133
fovea
region in centre of retina where overlying bipolar and ganglion cells are pushed away leaving only cones, provides sharpest image
134
rods
use principle of convergence – many rods converge on one bipolar cell, many bipolar cells on one ganglion cell – gives large receptive field and fuzzy image
135
cones
no convergence, one cone/bipolar cell/ganglion cell, smaller receptive field, high resolution image, less convergence = greater acuity
136
Center-surround organization of signal processing
enhances perception of borders and contrast, lateral inhibition from horizontal cells in surround
137
On center ganglion cells
light in centre of receptive field causes hyperpolarization of photoreceptor and reduced release of I glutamate, bipolar cells depolarize, increase NT release, and ganglion fire
138
off centre ganglion cells
light in centre of receptive field, photoreceptor hyperpolarization, reduced e glutamate, bipolar cell hyperpolarization, decreased NT release, ganglion inhibition
139
visual signal processing
optic nerves > optic chiasm > optic tract > lateral geniculate nucleus > visual cortex
140
Alpha 1 adrenergic receptor sensitivity
more sensitive to NE than E
141
alpha 1 adrenergic receptor cascade
NE binds GPCR and activates PLC > PIP > DAG + IP3 > PKC > activates Ca channel
142
alpha 1 adrenergic receptor action
Vasoconstriction to nonessential tissues
143
alpha 2 adrenergic receptor sensitivity
NE>E
144
alpha 2 adrenergic receptor cascade
NE binds GPCR, Gi subunit inactivates AC, decreased cAMP levels, inactivates PKA, dephosphorylates Ca channels
145
alpha 2 adrenergic receptor action
Negative feedback loop inhibiting NE release
146
beta 1 adrenergic receptor sensitivity
NE = E
147
beta 1 adrenergic receptor cascade
NE/E binds, GPCR activates AC, increased cAMP activates PKA, activates Ca channels
148
beta 1 adrenergic receptor action
Greater contractive force in heart
149
beta 2 adrenergic receptor sensitivity
E>NE
150
beta 2 adrenergic receptor cascade
E binds, GPCR activates AC, increased cAMP activates PKA, inactivates MLCK
151
beta 2 adrenergic receptor action
PKA hyperpolarizes cell making it more prone to contraction – vasodilation
