neurobiology Flashcards
1
Q
what does the hippocampus do?
A
formation of memories
2
Q
pituitary gland
A
production and release of hormones
3
Q
hypothalamus
A
homeostatic regulation
4
Q
wide laminar 4
A
sensory input
5
Q
wide laminar 5
A
motor output
6
Q
basket cells
A
inhibitory- innervate different layers or are confined to a single layer
7
Q
functional scan
A
detects changes in blood flow and metabolism
8
Q
lesion in parietal association cortex
A
lead to deficits in attention
contralateral neglect syndrome- cannot perceive objects or body parts in space
9
Q
temporal association cortex
A
recognition of objects and memory
10
Q
frontal association cortex
A
planning
11
Q
whats in the diencephalon?
A
epithalamus, hypothalamus and thalamus
12
Q
rubrospinal pathway
A
from red nucleus to spinal cord- magnocellular
from red nucleus to cerebellum- parvocellular
13
Q
mesencephalic locomotor region
A
important in regulating speeding pattern of motion
14
Q
epithalamus
A
circadian rhythms
15
Q
reticular nucleus
A
GABAergic input to thalamus
16
Q
sub thalamic nucleus
A
basal ganglia, motor control
deep brain electrode stimulation
17
Q
which layer is the lateral horn in
A
thoracic
18
Q
what does an alpha motor neurone do
A
innervates muscle
19
Q
wallenbergs syndrome
A
medullary
thrombosis of vertebral artery, wide ranging of sensory and motor deficits
- Ipsilateral loss from face- trigeminal system- taste
- Contralateral loss- pain/ temperature sensitivity
Dysphagia- glossopharyngeal and cranial
20
Q
brainstem glioma
A
account for approximately 10-20% of all childhood brain tumours.
double vision, weakness, unsteady gait, difficulty in swallowing, drowsiness, nausea, and vomiting. Rarely, behavioural changes or seizures may be seen.
21
Q
functions of reticular nucleus
A
ascending- control arousal- sleep, attention + awareness
descending- form reticule-spinal tract- posture
contribute to HR and respiration
22
Q
what does medullary nuclei of raphe nuclei do?
A
project to spinal cord and modulate pain transmission, movement and autonomic control
23
Q
what does rostral nuclei of raphe nuclei do?
A
project to diverse higher brain areas- modulate pain, mood and sleep-wake cycles
24
Q
axo-dendritc
A
excitatory- glutamate
25
axo-somatic
inhibitory- GABA
26
ago-axonic
modulatory and control transmitter release
27
what is presynaptic inhibition used for?
endogenous pain pathways- whether or not pain reaches CNS
1- C is inhibitory so depresses calcium current
2- reduction in transmitter released
3- synaptic potential reduced
28
neural integration
decision making
occurs at axon hillock
convergence and divergence
29
orthodromic direction
direction AP travels, from axon hillock to terminal
30
events at a chemical synapse
1- AP arrives at presynaptic terminal causing depolarisation
2-voltage gated calcium channels open
3-calcium rushes into the cell
4- calcium ions trigger neurotransmitter release
5-calcium influx can influence the shape of the action potential
31
where are neuropeptides manufactured?
in the cell body using protein manufacturing- rough ER and golgi apparatus
32
where are amines and amino acids manufactured?
in the synaptic terminal using synthesising enzymes that are transported from the soma
33
what is co-existence?
single neurone released more than one NT
34
3 ways to remove a NT
1- enzymatic break down- acetylcholinesterase
2-diffusion of neurotransmitter
3- reuptake of neurotransmitter
35
disinhibition
arrangement of inhibitory and excitatory cells in a circuit the generates excitation by transiently inhibiting a tonically active neurone
36
synaptotagmin
calcium sensor
37
synaptobrevin
binds to SNAP-25 to form a complex- moves vesicle into juxtaposed position with the membrane
38
3 integral membrane proteins
snaptobrevin
SNAP-25
snaptotagmin
39
ionotropic receptors
ion channels- action potentials
| fast response
40
metabotropic receptors
coupled to intracellular proteins that transduce signal
| slow response
41
how many subunits does GABA have
5
42
how many subunits does glutamate have
4
43
NMDA receptor
excitatory
needs to bind both glutamate and glycine
coincidence detector
allows sodium and calcium through- calcium acts as a secondary messenger for synaptic plasticity
44
noradrenaline on beta receptors
Gs- adenyl cyclase- cAMP- PKA- protein phosphorylation
45
metabotropic glutamate on mGLuR1
mGLuR1- Gq- phospholipase C- produces 2 secondary messengers
1- diacylglycerol- protein kinase C
2- IP3- Ca2+ release
increases protein phosphorylation and activate calcium binding proteins
46
dopamine
D2
Gi
decrease in adenyl cyclase- decrease in cAMP, PKA and protein phosphorylation
47
what happens when glutamate binds to mGLuR2
it is linked to Gi- decrease in adneyl cyclase and cAMP
48
hemicolinium
blocks reuptake of choline so decreases Ach signalling
49
vesamicol
inhibits Ach uptake- decreasing signal
50
botulinum
prevents release of Ach- muscle paralysis
51
nicotine
enhances activity of Ach
52
scopolamine
decreases activity of Ach
53
sarin
enhances activity of Ach
54
AchE is an unreliable thing to stain
1- it might be located postsynaptically
2- it could be serving other cellular functions
3- missing from cholinergic neurones
55
enzyme that catalyses glutamine to glutamate
glutaminase
56
enzyme that catalyses glutamate to glutamine
glutamine synthase
57
Nisl staining
number of neurone
| stains the cell body
58
Golgi staining
whole neurone
| stains dendrites and cell soma
59
layer 2 and 3 in the brain
small pyramidal cells
| excitatory neurones
60
layer 4 in the brain
stellate cells
massive dendritic aborisations
from the thalamus
61
layer 5 in the brain
large pyramidal cells
| output
62
layer 6 in the brain
pyramidal cells that project to the thalamus
63
what is an EEG
electrodes are placed on the head and the frequency is measured
frequency varies depending on the state of activity
64
superior colliculus
visual, acoustic and somatosensory info
in the tectal region
orientates the head and eyes towards a stimulus
65
inferior colliculus
acoustic
| sends info either to superior colliculus or to the thalamus
66
red nucleus
high iron content
| motor nucleus- output to cerebellum
67
rubrospinal pathway
important for fine control of movement
68
mesencephalic locomotor region
regulating speed of pattern of movement
69
mesocortical
ventral tegmental area to frontal cortex
| linked to schizophrenia
70
mesolimbic
ventral tegmental area to ventral striatum
| linked to OCD, ADHD and drug addiction
71
medial hypothalamus
homeostasis
72
lateral hypothalamus
sleep and wakefulness
73
voltage clamp
keep voltage the same but change the current
see what happens at different voltages
electrode in a single neurone
74
patch clamp
categorise ion channels
neuronal firing patterns
one in ECF and one in neurone
75
what is grey matter
neuronal cell bodies and dendrites
76
what is white matter
ascending and descending tracts
77
what is presynaptic facilitation
1- depresses K+ current in A terminal- depolarise for longer
2- calcium in A increases
3- increase in transmitter release in A and B
4- amplitude of synaptic potential in B increases
78
convergence
lots of inputs- only when all inputs come together might reach threshold and get an action potential
79
divergence
more than one axon- communication with more than one neurone
| e.g. a basket cell acts on 10 purkinje cells
80
breakdown of glutamate
1- in an astrocyte- glutamine synthase
2- reversal of transamine reaction
3- glutamate dehydrogenase
81
what is glutamate dehydrogenase
enzyme that catalyses glutamate to GABA
mainly found in axons
Inhibited by allylglycine
82
GABAa binding sites
```
1- GABA
2- benzodiazepines
3- steroid- anaesthetics
4- barbiturate- depressants
5- picrotoxin- convulsants
```
83
what are the requirements of the visual system?
high resolution vision
sensitive to wide luminance range
ability to move the eye, stabilise the image and adjust gaze
84
what are the constraints of the visual system?
mechanical constraints on the optic nerve- thin and flexible
| metabolic costs
85
what does the cornea do?
focuses the light on the retina
86
what does the iris do?
controls the size of the pupil in response to light intensity
87
what do the ciliary muscles do?
control the shape of the lens
88
what is accommodation?
changing the shape of the lens depending on near/far objects to focus light on the retina
89
what is resolution?
the ability to distinguish between 2 points
90
what happens in light- phototransduction
```
light absorbed by opsin
activates transducer (G protein)
alpha form binds to phosphodiesterase
this breaks down cGMP into GMP
ion channels close causing hyperpolarisation
```
91
receptive field
area of the retina that the ganglion cell is responsible for
92
receptive field centre
corresponds to the extent of the ganglion cell dendritess
93
what do starburst amacrine cells respond to?
motion moving away from the body
release more NT when a stimulus moves away along a dendrite
wired up to direction selective ganglion cells
94
what are bird detectors?
they are found in mice retina
they are strongly inhibited by motion in the large surround
sensitive to stimuli in the small receptive field
95
what happens if bright light on green on red off
green light on centre- excites RGC
red light on surround- excites amacrine cells- inhibits RGC
RGC compares how much green relative to red
96
what is the pigment melanopsin
responds best to blue light- between blue and green
97
iPRGCs
intrinsically photosensitive retinal ganglion cells
they encode how bright things are
contain melanopsin in the membrane so if all synaptic transmission is lost can still respond
will fire for a long and sustained time
>project to the SCN and OPN (olivary pretectal nucleus)
98
where does the vestibular system project to?
vestibular nucleus- oculomotor nerves
99
vestibule-ocular reflex?
allows you to focus on a point
100
accessory optic system
collection of 3 nuclei- anterior, medial and posterior- in pretectum
respond to global movements rather than local motion
only receive information from on DSCGCs
101
binocular field
area that overlaps between the left and right hemispheres
102
stereopsis
perception of depth
103
what is the magnocellular layer of the LGN
layers 1+2
parasol cells (M cells)
large cell bodies
104
what is the parvocellular layers of the LGN
layers 3-6
midget cells (P cells)
small cell bodies
105
where are the koniocellular layers in the LGN
between the layers
very small cell bodies
they match whatever is above them
106
what is retinotopic organisation?
The same all the way through
| visual space to ganglion cells to LGN- will be next to each other the whole way through
107
what does staining with cytochrome oxidase reveal?
columns running through the layers
| the columns are colour opponent- neurones in these regions are processing colour
108
lateral corticospinal tract
skilled limb movement
109
ventral corticospinal tract
axial muscle control
110
corticobulbar tract
controls primary facial muscles, jaw, and muscles for speaking and swallowing
red nucleus, RF.
111
rubrospinal tract
red nucleus
| limb control
112
tectospinal tract
originates from superior colliculus
| head-eye coordinating gaze
113
reticulospinal tract
diverse automatic movements and posture
114
vestibulospinal tract
for posture and balance
115
extrafusal fibres
generate muscle tension
| innervated by alpha motoneurones
116
intrafusal fibres
gain control function
| innervated by gamma motor neurones
117
what is proprioception?
sense of oneself
Receptors on skeletal muscles, joints, skin
Vision & Vestibular System
detected by golgi tendon organs and spindle
118
what is Exteroception?
sense of external world
All special senses
Somatosensory: contact, pressure, stroking, vibration, etc.
119
Ia afferent
spindle afferents and efferents
senses stretch and rate of change in stretch
excite alpha motoneurons
120
Ib afferents
tendon organ afferents
force change in muscle
inhibit alpha motoneurons
121
II afferent
spindle afferents and efferents
group 2 afferent
senses stretch only
122
reflex
a fast, predictable automatic response to a change in the environment or a stimulus
123
where does the corticospinal tract go?
tract to the spinal cord
| it is important for skilled movement
124
Plantar reflex/ Barbinski reflex
sole of foot is stimulated with a blunt instrument
normally- Plantar- the toes curl downwards
Babinski- the toes curl upwards- After loss of supraspinal or descending control (CST)
125
Lesions to reticulospinal and vestibulospinal tracts-
impaires gross movements but not fine
126
what does the basal ganglia consist of
corpus striatum, substantia nigra, globus pallidus, sub-thalamic nucleus
127
what is the direct pathway in the basal ganglia?
putamen to internal globus pallidus
128
what is the indirect pathway in the basal ganglia?
Putamen -> external Globus Pallidus -> Subthalamic nucleus -> internal Globus Pallidus
129
ataxia
bad movement
130
dysmetria
innappropiate displacement
131
hypotonia
weakness/ lack of muscle tone
132
Dysdiadochokinesis
inability to make rapid repetitive movement
133
Decomposition of movement
lack of co-ordination of different joints
134
mossy fibres
Mossy fibers -> excite granule cells -> weak affect on many Purkinje cells.
Directly :
Vestibular and spinal afferents(especially muscle spindles),.
135
climbing fibres
Climbing fibers -> contacts a few purkinje cells (~10) strongly excites them.
136
tactile receptors
sensations - mediated by low threshold mechanoreceptors, Merkel, Ruffini, Meissner & Pacinian types
137
Proprioception
mediated by muscle (spindle) & joint (Golgi tendon) receptors, some inputs from cutaneous mechanoreceptors
138
Thermal sensations
mediated by thermoreceptors localised to discrete zones that exhibit hot & cold sensitivity
139
Nociceptive (painful) sensations
mediated by mechanical, thermal & polymodal nociceptors
140
Meissner's
Low frequency vibrations
| rough texture and movement
141
Merkel’s disks
Small forms and shapes
epidermal/dermal border
detects form, shapes, rough edges, borders, texture
142
Pacinian Corpuscles-
High frequency vibrations
| fine texture and movement
143
Ruffini’s corpuscles
pressure
deep dermis
stretching, indentation or lateral movement
144
Free nerve endings
noxious- harmful
145
hair follicle receptor
light touch
146
nociception
sensory process that provides the signals that trigger pain.
147
1st pain
fast AD fibres
sharp or prickly
short duration
mechanical/ thermal nociceptors
148
2nd pain
slow C fibres
dull ache
slow onset but persistent
polymodal nociceptors
149
areas in spinal cord innervated by afferent
lamina 1+2- substantia gelatinosa
150
causes of hyperalgesia
A reduced threshold for pain
An increased intensity of painful stimuli
Spontaneous pain
151
5 categories of taste
sweet, salty, bitter, sour and savoury
152
Circumvallate papillae
largest, contain many thousands of taste buds, located at posterior
153
Foliate papillae
elongated structure, contain hundreds of taste buds, lie along posterior lateral edge
154
Fungiform papillae
smallest, contain one or two taste buds, widespread across anterior portion and tip of tongue
155
sequence of events for taste transduction
1- Dissolved molecules interact with sites OR modulate ion channels on apical microvilli
2- Triggers membrane depolarization & action potential firing
3- Accompanied by increase in intracellular calcium which initiates transmitter release
4-Transmitters excite afferent nerve fibres which combine to form cranial nerves (VII, IX & X) activated by taste stimuli
156
4 mechanisms in transduction cascade
Directly pass through ion channel
Bind to and block ion channels
Bind to and open ion channels
Bind to receptors that activate 2nd messenger systems that modulate ion channels
157
3 facts of neurodegenerative disorders
progressive
loss of neurones
irreversible
158
symptoms of parkinsons
```
rigidity
slurred and monotone speech
tremor
akinesia- difficulty in initiating movement
postural- stoop, shuffling and balance
```
