Neuro Flashcards
1
Q
What is the forebrain also known as?
A
Prosencephalon
2
Q
What is the midbrain also known as?
A
Mesencephalon
3
Q
What is the hindbrain also known as?
A
Rhombencephalon
4
Q
What is the brain also known as?
A
Encephalon
5
Q
Rostral to caudal
A
Nose to tail
6
Q
What does grey matter contain?
A
What neurone cell bodies
7
Q
What does white matter contain?
A
Myelin axons
8
Q
What are bundles of organised white matter called?
A
Fasiculus
9
Q
Describe association fibres
A
Stay in each hemisphere
10
Q
Describe commissural fibres
A
Fibres connect hemispheres e.g. corpus callosum
11
Q
Describe projection fibres
A
Carry impulses up and down
12
Q
What are the functions of the insula?
A
Disguise, emotion, self-awareness, homeostasis etc
13
Q
What are the functions of the frontal lobes?
A
Motor, problem solving, memory, language speaking, judgement etc
14
Q
What are the functions of the temporal lobes?
A
Understanding language, memory, primary auditory cortex, semantic processing
Auditory and recognition of faces and objects
15
Q
What are the functions of the parietal lobes?
A
Somatosensory - pain, touch, temperature
Dominant (usually left) - perception, language and mathematics
Right - visuospatial
16
Q
What are the functions of the occipital lobes?
A
Visual
17
Q
How many layers does the neocortex have?
A
6
18
Q
What is brodmann areas?
A
Mapping of the subdivisions of the cortex
19
Q
Describe the brain asymmetry
A
Right protrudes anterior, left posterior
20
Q
What is Broca’s area responsible for?
A
Language production
21
Q
What is the function of Wernicke’s area?
A
Language understanding
22
Q
What is the function of sinuses?
A
Drains used blood back to the brain and ventricles
23
Q
Describe the coronal plane
A
Ear to ear
24
Q
Describe the axial plane
A
Horizontal
25
Describe the Sagittal plane
Between eyes
26
Describe evolution of the brain
More complex threat detection and avoidance behaviour
->
Requires additional neural systems
27
What does the CNS contain?
Brain
Spinal chord
28
What does the PNS contain?
All other nerves
29
Describe the somatic nervous system
Interacts with the external environment
30
Describe the autonomic system
Unconscious regulation of the body’s internal environment
31
Name the 4 regions of the spine
Cervical
Thoracic
Lumbar
Sacral
32
Describe the dorsal and ventral roots of the spinal chord
Afferent (sensory) nerves have cell bodies in dorsal root ganglia and synapse win the ventral horn wither to an inter neurone or motor.
Efferent (motor) nerves travel in the ventral roots
33
What is the function of the cerebellum?
Balance and coordination
34
What is the function of the thalamus?
Sensory relay station (for all but smell)
Regulates sleep and arousal
35
What is the function of the hypothalamus?
Homeostasis, endocrine, body cycles etc
36
What is the function of the fornix?
Carries signals from hippocampus to mammillary bodies
Learning and memory - spatial navigation
37
What is the function of the caudate?
Planning + execution of movement
Memory, cognition, emotion etc
38
What is the function of the putamen?
Regulation of movement, cognition and reward
39
What is the function of the amygdala?
Emotional learning and behaviour, especially fear
40
What is the function of the cortical grey matter?
Higher processes- memory, thinking, problem solving, reasoning, consciousness, emotions etc
Sensory processing
Movement
41
2 scans to identify brain structures
CT - quicker
MRI - more tissue detail
42
What is the function of the medulla?
Sleep/wakefulness
Movement, circulatory, respiratory, excretory reflexes
43
What is the function of the PONS?
Relays cortex to midbrain and cerebellum
Pattern generators e.g. for walking
44
What are colliculus in the midbrain?
Superior - visual/orienting frequency maps
Inferior - frequency maps
45
What are the 3 sections of the midbrain?
Periaqueductal gray
Red nucleus
Substantia nigra
46
What is the function of Periaqueductal grey?
Defensive behaviour, pain and reproduction
47
What is the function of the red nucleus?
Pre-cortical motor control projects to spinal chord
48
What is the function of the substantia nigra?
Basal ganglia input
(Parkinson’s)
49
What is the function of the hippocampus?
Spatial and long term memory
50
What is the function of mammillary bodies?
Formation of recollective memory - amnesia
51
What is the function of the cingulate gyrus?
Behavioural outcomes to autonomic control - schizophrenia
52
Name some differentiated Glia cell types
Oligodendrocytes
Microglia
Astrocytes
53
Describe neurones
Input via dendrites and specialised axon propagates action potentials
54
2 types of synapses
Chemical - via neurotransmitters
Electrical - flow of ions directly through channels
55
Describe chemical synapses
Axon potential depolarises synaptic membrane which opens and leads to calcium influx. This triggers release of neurotransmitters.
56
Describe electrical synapses
Connexins form connexons = forms gap junction protein channels.
57
Describe neural plasticity
Changes in neuronal/synaptic structure/function for learning and memory in response to neural activity
58
List some neuronal heterogeneity
Size
Morphology
Neurotransmitters
Electrical properties
59
What are oligodendrocytes?
Unique to vertebrates, forms myelin sheath around axon for rapid conduction. Nodes of rangier allow for saltatory conduction.
60
Describe the myelin sheath
Formed from wrapping of Oligodendrocyte membranes
70% lipid, 30% protein
Myelin basic proteins can be detected
61
Describe microglia
Resident resting, motile immune cells of the CNS. Once activated, become amoeboid and is phagocytic
62
Describe astrocytes
Star like, highly heterogeneous cells. Most numerous glia and contains common marker protein (GFAP)
63
What is the function of astrocytes
Contributes to blood brain barrier containing aquaporins. Removes excess neurotransmitters from synapses and changes cerebral blood flow activity.
64
Name 3 specialised astrocytes
Radial glia - for development
Bergmann glia - cerebellum
Muller cells - retina
65
What is Motor neurone disease?
Adult onset neurodegenerative disease of loss of upper and lower motor neurones.
66
What is multiple sclerosis?
Autoimmune demyelination of ogliodendrocytes.
67
What are commissures?
Tracts that cross midlines
68
PNS axons are myelinated by what cells?
Schwann cells
69
Name the layers of the blood brain barrier
Endothelial
Basement membrane (fenestrations)
Astrocytes
Pericytes
70
Which organs lack normal blood brain barrier?
Circumventricular organs:
Post pituitary
Subformical organ
71
What are ependymal cells?
Line ventricular and central canal of spinal chord.
(Ciliated epithelial)
72
What is the function of ependymal cells?
CSF production, flow and absorption
Allows solute exchange between tissue and CSF
73
What is the main site of CSF production?
Choroid plexus (modified ependymal cells)
74
What waves are used in MRI?
Radio frequency
75
What is fMRI?
Scanner is sensitive to iron - active cells use oxygenated blood and therefore ‘reveals’ iron.
76
What does PET scan stand for?
Positron Emission Tomography
77
How does a PET scan work?
Contrast agent specifically targets biological process, is attached to radioisotope. Radiation emitted is detected
78
What does EEG measure?
Regional brain activity
79
How does TMS / TDCS work?
Induces an electrical current in the brain which switches off parts.
80
What are the 3 guiding principles for research involving animals?
Replacement
Refinement
Reduction
81
What are some possibilities of invasive methods? (Scanning)
Make direct measurement of activity
Determine connectivity between structures and flow of information
Lesion specific ctructures
82
During neurodevelopment, describe the main action of neurones.
Neurones arise in the germinal matrix, migrate to the cortisol sub plate and makes connections. Waiting until birth.
83
Describe neurodevelopment
Cranial to caudal
Proximal to distal
Simple to complex
84
Folic acid reduces risk of…
Spina bifida
85
What is anacephaly
No development of brain (baby dies)
86
Red flags for babies
Any loss of skil
Visually not following an object
Hearing loss
Squinting after 3-4 months
Cannot hold object after 5 months
No speech by 18 months
Not walking by 18 months(boys)
/ 2 years(girls)
87
Define sounds
The displacement of air particles following a sinusoidal pattern of compression and rarefacation
88
What range can we hear?
20-20000Hz
89
Describe the 4 components of the auditory system
Outer ear - air
Middle ear - air
Inner ear - fluid
Central auditory pathways
90
What are the components of the outer ear?
Pinna - cartilaginous structure
Ear canal - 1/3 cart, 2/3 bone
Tympanic membrane:
- 1/2 pats flaccid a (2 layers)
- Pats tens a (3layers)
91
What are the components of the middle ear?
Bones - malleus, incus, stapes
Muscles - tensor tympani, stapedius
Eustachian tube
92
What is the role of the middle ear?
Energy transfer from air to fluid
Amplification of airborne sound to make it louder
93
What is the role of muscles in the middle ear?
Protection of the inner ear from acoustic trauma
Deadens the sound of chewing
94
What is the role of the eustachian tube in the middle ear?
Ventilation and drainage of secretions equalises pressure
95
Describe the inner ear
Cochlear - 2.5 turns fluid filled bony tubes for hearing
Labyrinth - for balance
96
Describe the cochlear
3 compartments:
Scala tympani
Scala media
Scala vestibule
(Outer two encompassed in bone)
97
Describe the 2 cochlear fluids
Endlymph (Scala media)
- High K+
Perilymph (Scala Ty + ves)
- Na+ rich
98
Describe the process of the cochlear
1. Pressure waves move basilar membrane to organ of corti
2. Hair cells inside organ of cortisone and each one is gunned at different frequencies.
3. Hair attached to the tectorial membrane depolarises endolymph
3. Neurotransmitters released send signals.
99
Inner vs outer hair in organ of corti
Inner - mechanical transduction
Outer - fine tuning
100
Describe waves to sparks of inner hair cells. (Cochlear)
Movement or sterocilia opens K+ channels (depol) which open Ca+ channels and release neurotransmitters (Glutamate).
Repolarisation of K+
101
Frequency vs intensity
Pitch - nerves in location
Loudness - firing rate of nerves
102
From cochlear to brain
Auditory fibre
Spiral ganglion
Cochlear nerve
Central auditory pathway
(E.C.O.L.I.)
103
How does brain stem localise sound?
Depending on time differences of sound arriving from right and left ear to see position of sound.
104
Names of hearing loss
Defective outer/middle ear
= Conductive hearing loss
Defective Inner ear
= Sensorineural hearing loss
105
Name the 3 types of muscle
Smooth (visceral, voluntary)
Skeletal (striated, involuntary)
Cardiac
106
Describe histology of skeletal muscle
Myofibres surrounded by connective tissue:
-Epimysium
-Perimysiu-Endomysium
Basement membrane
Capillary to each cell
Each fibre innervated by a nerve
107
Describe neurones to skeletal muscle
Primary motor cortex
Through basal ganglia systems and cerebellar systems
To anterior horn cell (lower motor neurone)
To muscle
108
Pathology of lower motor neurone
Motor neurone disease
109
Pathology of Cerebellar system
Peripheral neuropathies
110
Pathology of muscle
Primary muscle disease (myopathies)
111
Describe enzyme histochemistry of muscle tissue
Frozen sections warmed up reactivates enzymes and electron microscopy shows different colours.
112
2 types of muscle fibre types
Slow twitch - type 1, oxidative, fatigue resistant
Fast twitch - fatigue rapidly but generates large peak of energy
- 2A - Glycolytic + oxidative
- 2B - glycolytic
113
Define a motor unit
A motor neuron and the fibres it innervates (all of same type)
Fibre type dependent on neurone and size of motor unit varies between muscles.
114
Describe denervating diseases
Loss of innervation causes fibre atrophy, but sprouting from adjacent motor units allow reinnervation. Conversion of fibres result in fibre type grouping
115
What is a sarcomere?
Basic unit of contraction in a muscle fibre
116
Name the different bands in a sarcomere
Z disc
I band
H band
A band
117
Describe the sliding filament theory (muscle contraction)
Myosin head binds to actin
ATP binds and is hydrolysed allowing myosin head to release and move further along chain.
118
What is creatine phosphate?
Short term energy store.
Creatine Kinase sticks P- to form CP
119
What is mitochondrial cytopathies?
Maternally inherited mitochondrial DNA is damaged/ mutated.
Heteroplasmy = only some DNA mutated gives symptom variation
120
How to diagnose mitochondrial cytopathies
In muscle biopsies = ragged red flag or abnormal morphology
121
What are dystroglycans?
Link Intracellular proteins of sarcolemma to external matrix protein for stability
122
What are dystrophies?
Genetically determined, destructive and mainly progressive disorders of the muscle
123
Describe neuromuscular transmission
Depolarisation of presynaptic membrane releases ACh which binds to receptors and propogates action potential across the t-tubules. Ca2+ is released.
124
What is myasthenia graves?
An autoimmune neuromuscular transmission disease where Anti-AChR antibodies reduce ACh receptors
125
What is damage to motor or sensory neurones called?
Neuronpathies
126
What is damage to axons called?
Axonopathies
127
What is selective damage to myelin sheaths called?
Demyelination
128
Describe axonal regeneration
Axonal sprouts form from proximal part of damaged axon and grows along columns of proliferating Schwann cells to remyelinate
129
What are extraocular muscles?
Muscles in the eye orbits
130
Name all 7 extraocular muscles
Levator palpebrae superioris
Medial rectus
Lateral rectus
Superior rectus
Inferior rectus
Superior oblique
Inferior oblique
131
Which 3 cranial nerves are involved in movement of eye?
3 - oculomotor
4 - trochlear
6 - abducens
132
Which cranial nerves supply which extraocular muscles?
4 - superior oblique
6 - lateral rectus
3 - rest
133
What is the origin of the extraocular muscles?
Attached to orbital bones and insert into sclera (apart from LPS into upper eyelid)
134
Looking straight, orbital axis does not coincide with optical axis so…
Direction of muscle fibres don’t coincide with optical acis
135
Movement of levator palpebrae superioris
Elevates upper eye lid
136
What is ptosis?
Drooping of eyelid (3rd nerve injury)
137
Movement of the medial rectus
Moves eye medially
138
Movement of the lateral rectus
Moves eye laterally
139
What can oculmotor nerve lesion lead to?
Weak medial rectus so eye deviates laterally and experiences double vision (diplopia)
140
What can abducens nerve lesion lead to?
Lateral rectus weakness so eye deviates medially and experiences double vision (diplopia)
141
Movement of the superior rectus
Up and laterally
142
Movement of the inferior rectus
Down and laterally
143
Movement of the superior oblique
Medially and down
144
Movement of the inferior oblique
Medially and up
145
How to examine medial and lateral rectus
Move finger horizontally:
Medial - moves eye medially
Lateral - moves eye laterally
146
How to examine superior and inferior rectus?
Move finger laterally
SR - should follow finger up
IR - should follow finger down
147
How to test superior and inferior oblique
Move inferior medially
SO - will follow finger down
IO - will follow finger up
148
What are the vestibular structures?
3 semicircular (90degrees) canal and in semicircular ducts that contain fluids. Endolymph (fluid) drains into utricle (sac) and saccule.
149
What is the function of the semicircular ducts?
Balance:
When head moves in one direction, endolymph moves to the opposite. Cupula and hair cells in the ampulla bend and send info via CN 8 to nuclei in the medulla.
150
Describe vestibular nuclei
Nuclei of brain stem makes connection with nuclei of CN 3,4,6 to control posture, balance and position.
151
What is the oculocephalic reflex?
Maintaining fixed gaze when head is moving.
(Absent reflex indicates brain stem lesion)
152
What is materialism?
Mental states are actually physical
153
Define dualism
Mental and physical states are both real
154
Define idealism
Physical states are really mental
155
What are some challenges to dualism?
Inexplicable symptoms
Impact of environment / societ
156
Neurology vs Psychiatry
N - focus on diagnosis of abnormal brain chemistry, genetics, structure et
P - focus on diagnosis and formulation e.g. interaction with environment, psychological, cultural issues etc
157
Schizophrenia symptoms
Delusions
Hallucinations
Thought disorders
Negative symptoms:
Withdrawn, reduce self care and social contact
158
What are some biological correlations to schizophrenia?
.Smaller brain volumes
.Functional imaging - dysfunction in regions associated with hallucinating
.Dopamine theory - blockers as treatment
.Genetics
159
What are some non-biological correlations to schizophrenia?
More common in:
Urban areas
Ethnic minorities
Association with trauma
High expressed emotion, loss
160
Adv of classification of mental disorders
Inform public health for allocation of resources
Promote feelings of understood
Provide framework for research
161
Disv of classification of mental disorders
Can lead to stigma and prejudice
Oversimplification
162
Define emotion
Strong feeling deriving from one’s circumstances, mood or relationship with others.
163
What is the role of emotion?
Motivator for learning
Thoughts
For best obtaining rewards/avoiding punishment
164
Name 4 theories of emotion
Basic
Appraisal
Psychological constructionist
Bayesian model
165
Describe neuroanatomy of emotion
Limbic system is network of connections
166
3 steps of emotion
Identification (smell, taste, sight)
Appraisal (Amygdala, orbitofrontal cortex)
Reactivity (cingulate cortex)
167
Describe the orbitofrontal cortex (appraisal)
Medial: reward
Lateral: punishment
168
Describe the amygdala (appraisal)
Conditioned response to harmful stimuli
Facial expression recognition
169
Describe the cingulate cortex (action-outcome learning)
Anterior: outcome (reward+punish)
Posterior: action
Mid: action
170
What happens at the ventromedial prefrontal cortex?
Reward related decision making
171
What are autonomic responses regulated by?
OFC
Amygdala
172
What happens at the inferior frontal gyrus?
Behavioural suppression
173
What happens at the precuneus?
Autobiographical memory, spatial navigation
174
What happens at the PCC?
Self reflection + image, retrieves autobiographical memories.
175
Where does the nervous system develop from?
Ectoderm
176
Describe development of spinal chord until 4 weeks.
1. Signals from notochord causes inward folding of ectoderm at the neural plate.
2. Ectoderm thickens in midline and ends fuse to form neural tube.
177
Describe development of spinal chord after 4 weeks.
Lateral to neural grove lie presumptive neural crest cells that migrate to different organ systems.
These form neurones, Schwann cells, melanocytes, osteoblasts, adipocytes and Chondrocytes.
178
Describe some abnormalities of the spinal chord
Neural tube usually closes at 4th embryonic week.
Failure to close Cephalic region
= Anacephaly
Failure to close spinal region
= spina bifida
179
What are neural tube defects?
Failure to close spinal chord at 4th embryonic week
180
What does prosencephalon form?
Cerebral hemisphere, thalamic structure
181
What does the mesencephalon form?
Midbrain
182
What does the rhombencephalon form?
Medulla, pons, cerebellum
183
Describe development of brain
Stem cells from ventricular zone migrate to outer surfaces.
184
Micro vs Macrocephaly
Micro - reduced head circumference (bottom 2.5% of population)
Macro - increased head circumference (top 2.5%)
185
Which is more severe? Micro vs macrocephaly?
Macrocephaly
186
What is the function of CSF?
Cushion the brain and help circulate metabolites
187
What is hydrocephalus?
Accumulation of CSF with increased inter cranial pressure.
Can cause macrocephaly
188
Define sensation
A mental process resulting from immediate external stimulation of sense organ
(Touch, smell, taste, sight)
189
Define perception
Ability to become aware of something following sensory stimulation.
(Tactile, olfactory, visual, auditory)
190
*What is a perceptual set?
The psychological factors that determine how you perceive your environment.
Believing is seeing
191
Sensation vs perception
Bottom up
Vs
Top down
192
*Factors that affect perceptual set
Context, culture, expectations, mood & motivation
193
What are Gestalt principles?
Principles of human perception that describe how humans group similar elements
194
What is the thatcher effect?
The interpretation of faces even when the faces are weird
195
Define illusion
Misinterpreted perception of a sensory experience
196
Define hallucinations
Apparent perception of something not present
197
What is the percentage of people who have experienced hallucinations?
5%
198
Out of people who experienced hallucinations, what % is due to mental conditions?
30%
199
Some causes of hallucinations
Neurological conditions
Drugs
Derilium
Sleep deprivation
Psychiatric illness
200
Hallucination is a form of what process?
Top - Down
201
What is the bio-psycho-social model?
Important for managing mental illnesses.
202
Hallucinations are experienced uniquely due to …
The perceptual set
203
What does the prosencephalon contain?
Cerebral hemispheres, basal ganglia
204
What does the diencephalon contain?
Thalamus, Hypothalamus, subthalamus, epithalamus
205
What is the mesencephalon?
Midbrain
206
What does the rhombencephalon contain?
Pons
Medulla
Cerebellum
207
What divides the frontal and parietal lobes?
Central sulcus
208
What separates the frontal and temporal lobes?
Sylvia’s fissure / Lateral sulcus
209
Name a white matter tract
Corona radiata
210
Mental illness vs psychological dysfunction
Car broken
Vs
Car fine but don’t know how to drive it well
211
Name 4 major neurotransmitters
Noradrenaline
Dopamine
Serotonin
Acetylcholine
212
Adrenaline vs noradrenaline
A - can’t pass blood brain barrier
N - produced in brain. (Causes stress)
213
What is CBT
Cognitive Behavioural Therapy
214
Why do we have 2 eyes?
Allows us to see 3D
Widens our visual field
215
What happens when the eyes don’t move together?
Diclopea (double vision)
216
How many layers in the eye?
3
Outer - sclera and cornea
Middle - choroid
Inner - retina
217
What is the function of the sclera?
Tough fibrous coat made of collagen to maintain shape and protect from trauma and infection.
218
What is the function of the cornea?
Parallel fibres of collagen transparent to allow light through. Responsible for 2/3 refractive power
219
How many layers in sclera / cornea?
5
220
Describe layers in sclera / cornea?
Epithelium - Can regenerate after abrasion
Bowman’s layer
Stromatolites - for clarity
Descemets layer
Endothelium - Keeps cornea hydrated and supplies nutrients
(Not regenerated when hurt)
221
What parts of middle layer?
Iris
Ciliary body
Choroid
222
Describe function of iris
Contains dilator and sphincter pupillae muscles
Aqueous humour maintains pressure in anterior chamber
223
Describe function of ciliary body
Glandular epithelium produce aqueous humour
Attached to lens by suspensory ligament so controls accommodation
224
Describe function of choroid
Blood supply to 1/3 of retina
225
What is the function of the retina?
Transducers light to electricity
226
Describe the areas of the retina
Macula lutea - important for central vision
Fovea central is - centre of macula
Cones
Rods
227
Difference between cone and rod cells
Rod - Lower resolution, Black or white, synapses Many-1
Cones - Higher resolution, colour, synapses 1-1
228
Describe layers in retina
Photoreceptors (rods+cones)
| Supported by horizontal cells
Bipolar cells
|Supported by amacrine cells
Ganglion cells
(Merges to form optic nerve)
229
Describe chemical reaction of phototransduction
In discs of rod /cone cells:
Photon converts 11-cis-retinal to 11-trans-retinal
Enzyme uses energy from ATP to reverse
230
Describe the lens
Biconvex
Responsible for 1/3 refractive power of eye
231
What is emmetropia?
Perfect vision
232
What is hypermetropia?
Refractive power too weak when looking at near objects
= long sighted
233
Reasons for hypermetropia
Lens not flexible enough
Axial length of eyeball short
Corneal curvature too shallow
234
Describe myopia
Refractive power too strong when looking at far objects
= short sighted
235
Reasons for myopia
Corneal curvature too steep
Axial length of eyeball too long
236
What is in the posterior segment?
Vitreous (more fluid) humour
Collagen
Hyaluronic acid (GAG)
Avascular viscoestalic gel
237
Name the layers of the adnexaa (eye lid)
Lids
Conjunctiva
Tear film
238
Describe the layers of the lids
Meibomian glands - oily secrete
Obicularis oculi - muscle closes lid (CN 3)
Tarsal plat - separates layers
Levator palpebrae superioris - Elevates lid
239
Describe layers of the conjunctiva
Palpebrae (under eyelid)
Bulbar (on eye)
Limbal stem cells
Goblet cells
Lymphoid cells (protective)
240
Describe the 3 layers of the tear film
Anterior lipid - Prevents evaporation
Middle aqueous - Hydrates + nutrition for cornea
Posterior mucous - Lubricates + aids even distribution
241
Describe blood supply of retina
Outer 1/3 by choroid
Inner 2/3 by central retinal artery
242
Describe retinal veins
Superior ophthalmic v. -> cavernous sinus -> internal jugular v.
Internal ophthalmic v. -> pterygoid venous plexus
243
Why is there risk of infection spreading from eye to brain?
Valvless vein system to cavernous sinus
244
Is there lymphatic drainage from lobe?
No
Only from lids and conjunctiva
245
Describe the resting potential
Sodium-potassium pumps actively transport 3Na+ out and 2K+ into neurones. More leaky K+ channels (out) gives -70mv membrane potential.
246
Describe excitatory neurotransmitters at start of post-synapse
Depolarises cell membrane
Increases probability of action potential
= Excitatory Post Synaptic Potential
247
Describe inhibitory neurotransmitters at start of post-synapse
Hyperpolarises the membrane
Decreases probability of action potential
= Inhibitory Post synaptic Potential
248
Depolarisation only occurs above…
Threshold potential
249
Describe depolarisation
Na+ channels open and floods in down electrochemical gradient. At -50mv, depolarisation opens even more Na+ channels.
250
Describe Repolarisation
At +30mv, Na+ channels close and K+ channels open so K+ flood out down an electrochemical gradient.
251
Describe hyperpolaristion
A slight overshoot of Repolarisation restores resting potential through sodium-potassium pumps
252
Spatial vs temporal summation to reach threshold
S - Multiple presynaptic neurones converge
T - Single presynaptic neurone has high frequency of neurotransmitters released.
253
What increases action potential speed
Higher temperature- energy
Wider axon diameter
Myelin sheath - saltatory conduction
254
What is Multiple sclerosis?
Axonal transmission failure
E.g. tremor, slurred speech, paralysis, weakness
255
How wide is a synaptic cleft?
20-30 x10-9m wide
256
Why’s is Novichok dangerous?
Disrupts normal synaptic neurotransmittion of acetylcholine
257
How are neurotransmitters removed?
Enzyme degradation
Reuptake
258
Describe synaptic transmission
Action potential opens Ca2+ channels and it floods in. This causes vesicles to fuse with membrane and release transmitters. Diffuses across synaptic cleft and binds to receptors which opens Na+ channels.
259
Name 5 main processes of synaptic transmission
1. Manufacture
2. Storage (vesicles)
3. Release
4. Diffusion
5. Inactivation (breakdown)
260
Name 3 fast neurotransmitters
Acetylcholine
Glutamate
GABA
261
Name 3 slow neuromodulators
Dopamine
Noradrenaline
Serotonin
262
How do local anaesthetics work?
Na+ channel blockers
263
What affects acetylcholine?
Cigarettes
Nerve gases
264
What affects noradrenaline?
Antidepressants
Stimulants
265
What affects dopamine?
Antipsychotic drugs
Stimulants
Anti-Parkinson drugs
266
What affects serotonin?
Hallucinogens
Ecstasy
Antidepressant drugs
267
What affects GABA (inhibitor)
Anaesthetics
Anticonvulsant drugs
268
Name photo pigment in rod cells
Rhodopsin
269
Name photo pigment in cone cells
Opsin - sensitive to light
270
What is special about photoreceptors?
They can produce a graded response
(But ganglion is not graded)
271
What describes structure of lacrimal gland?
Exocrine lobulated tubulo-acinar gland
272
Which gland is responsible for baseline tear formation (aqueous)?
Lacrimal and Accessory Lacrimal glands
273
Which is the outermost layer of the tear film?
Lipid
274
What gland produces lipid in tear film?
Meibomian glands, Zeis, Moll
275
What produces mucus in tear film?
Conjunctival goblet cells
276
How to test stroke vs Bell’s palsy?
If patient can lift forehead = stroke
277
Define pain (IASP)
Pain is an unpleasant sensory and emotional experience associated with, or resembling that associated with actual or potential tissue damage.
278
Name 4 purposes of pain
Immediate pain
Persisting pain
Nociception
Nociceptive pathways
279
Function of immediate pain
Warns of imminent tissue damage = withdraw from source of injury
280
Function of persisting pain
Encourages immobilisation of injured area to give damaged tissue best chance to heal.
281
What is nociception?
Neural neural processes involved in producing sensation of pain
282
Describe nociceptive pathways
Transduction in periphery, through dorsal horn of spinal chord, then to brain.
283
Acute vs chronic pain
Acute < 12 weeks
Chronic > 12 weeks and persists beyond tissue heating time
284
Name the two categories of chronic pain
Chronic non-cancer pain
Chronic cancer pain
285
Name 3 types of pain
Nociceptive pain
Neuropathic pain
Nociplastic pain
286
Define nociceptive pain
From actual or threatened damage to non-neural tissue due to activation of nociceptors.
287
Define neuropathic pain
Caused by lesion or disease of somatosensory nervous system
288
Define nociplastic pain
Pain from altered nociception but with no evidence of tissue damage or disease and lesions.
289
Examples of neuropathic pain
Phantom limb pain
Diabetic neuropathy
290
Define allodynia
Pain due to stimulus that does not normally provoke pain
291
Define dysesthesia
Unpleasant abnormal sensation, whether spontaneous or evoked.
292
Hyper vs hypoalgesia
Hyper - Increased pain
Hypo - Diminished pain
From a stimulus that normally invokes pain
293
Describe pathway of pain via neurones
Peripheral receptor - Detects stimulus
1st order neurone - periphery to ipsilateral spinal chord
2nd order neurone - crosses to contralateral and ascends to thalamus
3rd order neurone - thalamus to midbrain and higher cortisol centres
(Synapses between each neurone)
294
Define emotion
A mind and body’s integrated response to a stimulus.
295
What happens when we feel emotions
Physiological arousal (increase in reactivity to prime us for an event)
Expressive behaviour
Conscious experience
296
Izzards 10 basic emotions
Joy
Surprise
Sadness
Anger
Contempt
Shame
Fear
Disgust
Guilt
Excitement
297
Describe hemispheric lateralisation
Right hemisphere = negative emotions
Left hemisphere = positive emotions
298
Define mood
Long term emotional states, rather than discreet, fleeting feelings
299
Define mood disorder
Longer term extremes of emotional state and challenges in regulating mood.
300
Describe depression
Lowering of mood, reduction of energy etc.
Biological symptoms - poor sleep, appetite, concentration
Cognitive symptoms - worthlessnes, guilt, suicidal thoughts
301
Describe bipolar affective disorder
2< episodes where mood and activity level are significantly disturbed.
302
Mania vs hypomania
Mania = mood is elevated
Hypo = not to extent of disruption of work or social rejection
303
Describe function of nociceptors
Transduction of physical stimulus to action potential
304
Which primary afferent fibres are slower?
C fibre
(A-alpha is faster
A-beta
A-delta)
305
Cell bodies of primary afferent neurones lie where?
Dorsal root ganglion (body)
Trigeminal ganglion (face/head/neck)
306
What type of neurones are 1st order neurones?
Pseudo-unipolar
307
Where do 1st order neurones synapse?
Dorsal horn
308
Describe function is the 3 ascending tracts (sensory 2nd order white matter neurones)
Doral columns - fine touch, vibration
Lateral spinothalamic tract - pain, temperature
Ventral spinothalamic tract - light touch
309
Describe route of 2nd order neurone
Axon originates from spinal chord, decussates few levels above, crosses midline in anterior commissure to form anterolateral tract
310
Describe pathway of 3rd order neurones
Cell bodies in thalamus then travels to sensory cortex (post central gyrus)
311
What is the pain matrix?
Parts of the brain involved in pain:
Insula - degree of pain
Amygdala - learned emotional responses
Cingulate cortex - emotion formation
Peri-aqueductal gray - modulates pain
312
Define chronic pain
Complex abnormal pain with bio-psycho-social aspects.
313
How can we treat pain?
Stimulate descending inhibitory pathway
Gate control (peripheral stimulation of other fibres to block pain)
Pharmacotherapy (drugs)
314
Problems with long term opioid use
Tolerance
Immunosuppressive
Opioid induced hyperalgesia (opioid pain as well as original pain)
315
What are some chemical findings of depressions
Increased Corticotropin production
Reduced -ve feedback in brain
Reduced GR expression
316
How does stress affect the brain?
In the HPA Axis:
Reduces neurogenesis (new neurones)
Neurotoxic
Reduced BDNF levels
Affects dendritic formation
Affects frontal lobes and hippocampus
317
Where does neurogenesis occurs?
6% of total dendrites, and axons grown in the hippocampus every month.
318
How do antidepressants work?
Affects gene GR expression
Increases neurogenesis
Increases BDNF synthesis
319
What is MDD?
Neurodegenerative disease of impaired plasticity
320
What is the default mode network?
Resting state
- Daydreaming, internal flow of consciousness, social judgments
(Depressed find turning DMN off hard)
321
What is entropy? (2nd law of thermodynamics)
Measure of disorder
322
How does brain reduce entropy?
Makes predictions (top-down processing)
Can eventually form core beliefs e.g. ‘I’m fat’
323
What is depression (cellular level)
Disease of reduced plasticity (reduced connecitvity)
Increased self-referential thinking
324
Name the 5 pillars of well-being (NHS)
1. Physical activity (resets HPA axis)
2. Connect with others
3. Learn something new (turn off DMN)
4. Practice mindfulness (reduces DMN)
5. Acts of generosity
325
4 types of motor control
Voluntary
Goal-directed
Habit
Involuntary
326
Describe hierarchical control architecture
More complex, sophisticated threat detection and avoidance requires additional and complex processing capacity
Motor -> Autonomic -> Endocrine
327
Overview of sensorimotor system
Motor control by lower (spine to muscle) and upper (higher centres to lmn) motor neurones.
328
How do we achieve a range of movements?
Antagonist arrangement - e.g. eye
Recruitment of different muscle fibres - fast/slow twitch
329
What is rigor Mortis?
Release of acetylcholine causes cascade of ca2+, Mg+ and ATP to be released.
After death muscles remain contracted until enzymes disrupt the actin/myosin
330
Fewer muscle fibres in a motor unit gives…
Greater movement resolution
331
What is a motor pool?
All lower motor neurones that innervate a single muscle
332
A good CNS needs to know what about muscles
1. How much tension is on the muscle
2. What is the length (stretch) of the muscle
333
What do Golgi tendon organs sense?
Muscle tension
(Under extreme conditions can inhibit muscle fibres to prevent damage)
334
What do muscle spindles sense?
Length of muscle (stretch)
335
What are reflexes?
Operate without engaging the brain for avoidance of injury and effective motor control.
336
Intrafusal vs extrafusal muscle fibres
Extra - Normal muscle fibres
Intra - sensory fibres coiled around used to detect stretch
337
Gamma vs alpha innervation
Gamma motor neurones to keep intrafusal fibres at set length
Alpha - for muscle contraction
338
Describe reciprocal innervation
Contraction of one muscle induces relaxation of the other to permit smooth movement.
339
Where are motor and sensory neurones?
Sensory - dorsal root ganglion
Motor - ventral root
340
Control of gross movement has simple circuits but why is it hard to replicate?
Needs constant modulation based on sensory feedback to adjust activity and direct it towards its goal
341
Describe ancient brain stem motor control
Pathways connect sensory input to motor output directly e.g. balance, respiration and posture
342
How is motor control more adapted in humans?
Cortex sculpts commands into more developed.g. Grunts to voices
343
Describe primary motor cortex
Top down control over muscular activity with little synapses between a corticol neurone.
344
Describe general descending pathways from cortical motor areas
Upper motor neurones originate in pyramidal cells and synapse with lower motor neurones in spinal chord. Most innervate contralateral motor units
345
Axons of the upper motor neurones form
The pyramidal tract
346
Which areas of the brain affect motor control systems
Cerebellum = excitatory
Basal ganglia = Inhibitory
347
Describe dorsolateral tracts
Contains direct corticospinal tract and indirect route via brain stem red nuclei.
Innervates contralateral spine to alpha motor neurones directly and project to distal muscles e.g. fingers
348
Describe ventromedial tracts
Contains direct corticospinal tract and indirect route via brain stem tectum, vestibular and CN nuclei.
Diffuses Innervation to both sides and projects to proximal muscles of trunks and limbs.
349
Define the basal ganglia
A group of structures (group of nuclei) beneath the cortex that acts as a Gatekeeper for control of the motor system. (Not fully understood)
350
Describe function of basal ganglia.
Receives excitatory input from cortex and outputs inhibitory (GABA) response back via the thalamus at rest.
Dopamine from substantia nigra dishibits basal ganglia and increases excitation to motor cortex.
351
Describe the cerebellum
Acts as a parallel processor enabling smooth, coordinated movements. Also important in cognitive tasks.
Contains half number of CNS neurones and 10% of brain weight.
352
Describe the function of the cerebellum
No direct projection to LMN - modulates activity of UMN. Computes errors back to motor cortex and adjust commands while motor learning = precise control + coordination
353
Name 3 inputs of cerebellum and 1 output
I = Corticol - copy of commands from motor, somatosensory and visual areas of cortex
I= Spinal - proprioceptive info about limb position and movement
I= Vestibular- Rotational and acceleratory head movement.
O = Thalamus -> motor cortex
354
Autonomic vs somatic system
Involuntary, generally smooth/ cardiac muscle/ glands.
Voluntary, more organised nerves, always stimulates skeletal muscle contraction.
355
Parasympathetic vs Sympathetic innervation
Para - CN 3,7,9,10 and Sacral 1,2
S - CN, white + grey rami, sympathetic chain (splanchnic T1-L2), other ganglia
356
Autonomic vs somatic motor neurones
Myelinated Fibres synapse at ganglion after CNS and postganglion fibres are unmyelinated
Myelinated Fibres don’t synapse after leaving CNS
357
Some examples of autonomic functions
Thermoregulation, exercise, digestion, sexual function
358
What happens in sympathetic innervation?
Bronchodilator, vasoconstriction, increased heart rate and blood pressure, decreased GI motility and contraction.
(Opposite for para)
359
Name 3 systems of the autonomic system
1. Para (CN + Sacral)
2. S (Adrenal amplification)
3. Enteric NS (GI)
360
Describe the adrenal amplification system
The adrenal glands over kidneys secrete more adrenaline which circulate and amplify fight or flight responses by about 5x
361
Describe the enteric NS
Allows GI to function without para/sympathetic NS by allowing neurotransmitters circulating in portal system to allow digestive enzymes to be released
362
Describe neurotransmitters and receptors in parasympathetic and sympathetic neurones
Sympathetic - Ach (Nicotinic receptor), Noradrenaline (Adrenergic receptor)
Parasympathetic- Ach (nicotinic receptor), Ach (Muscarinic receptor)
363
Name some ANS inputs
Carotid body receptor (in bifurcation)
Atrial baroreceptors
Cardiac baroreceptors
Arteriolar receptors
364
Name some primary and secondary ANS disorders
P - Acute, chronic
S - Diabetes, Chronic liver, renal,, alcohol induced, Guillain-Barre (inflammation), infection, brain tumours, Hypertension*, sexual+sudomotor+GI+eye disorders
365
How to test autonomic nervous systems
Heart rate and blood pressure measurement using:
Stress test
Bp beat-by-beat
Baroreflex
Non cardiovascular test:
Pupillarometry
Sweat measurement
Skin blood flow
Gastric acid secretion
366
What is the basal ganglia
Part of telencephalon that is not directly connected to but influences motor control.
367
What is the lenticular nucleus made of?
Putamen
Globus pallidus
368
What is the striatum made of?
Caudate nucleus
Putamen
369
What is the corpus striatum made of?
Caudate nucleus
Putamen
Globus pallidus
370
MRI facts
Always on - magnetic rays
Cannot take in money, phones etc
Implants, heating, projectile hazards
-> May cause death
Need to fill form before using
371
Describe beginning of motor movement
Motor cortex
Brain stem
Spinal chord (Ventral horn)
372
Common causes and features of UMN disorder
Brain stem - stroke/ tumour/ MS
Spinal chord - Vit B12 deficiency, spinal chord degeneration, cord compression
Spastic, Spastic /pyramidal weakness, Brisk reflexes, + Babinski reflex
373
Causes and features of LMN disorders
Motor neurone - MND, Polio
Motor nerve root - Guillain Barre
Motor nerve - neuro / radiculopathies
Neuro muscular junction - Myasthenia gravis
Muscle - Myositis, myopathies
Weakness (flaccid), muscle wasting, fasciculation, absent deep tendon reflex, reduced tone
374
Causes and Features of peripheral nerve or neuromuscular junction disorders
P - Diabetes, HIV, Alcohol/Drugs, Paraneoplastic syndrome
N - Myasthenia gravis …
Weakness and muscle wasting, Poor balance, Numbness, burning, tingling, freezing pain
375
What is myasthenia gravis? Describe
Antibody mediated immune system attacks neuromuscular junction
376
Describe structure of a skeletal muscle
Muscle cell = fibre (one cell with nucleus)
-> myofibrils -> sarcomeres
Made of actin and myosin filaments which slide over each other for contraction
377
Which systems ensure smooth and coordinated movement?
Extra pyramidal system - Basal ganglia
Cerebellar system
Sensory input
378
Describe Parkinson’s disease
Neurodegenerative condition associated with loss of dopaminergic neurones so the basal ganglia is inhibited and motor cortex is uninhibited. Systems (TRAP):
Tremor
Rigidity
Akinesia / Bradykinesia
Postural instability
379
Describe importance and features of cerebellar disorders
Important for coordination: limb movement, clear speech, smooth eye movement, maintaining posture
Features : dysarthria (slurring), Unsteadiness, nystagmus, lack of smooth fine movements.
380
What can chronic pain affect?
Ability to work
Activities and enjoyment
Contact with others + relationships
Self confidence + sleep
381
Describe 2 common patterns of pain
Take it easy - avoid activities due to fear = loss of contact and fitness
Boom and bust - aggrieved pain and then rest repeatedly
382
3 Ps to help pain
Pacing - regular activity
Prioritising - spreading activities
Planning - balance choices
383
Effects of muscle tension with pain
Muscle tenses in anticipation to pain causing aches with simple movements.
Beneficial to practice relaxation, mindfulness and distraction
384
Describe sub grouping of basal ganglia in 17th century
Rostral (upper)
- Striatum (putamen + caudate)
- Globus pallidus
Caudal (lower)
- subthalamic nucleus
- Substantia nigra
385
Describe the position of the striatum
Caudate nucleus runs along lateral ventricles and putamen latera, to this.
(Together = striatum)
386
Describe the position of the caudal structures
Red nucleus is above substantia nigra.
Subthalamic nucleus is lateral.
387
Which 3 circuits is the basal ganglia involved in?
Motor
Limbic (emotion)
Oculmotor
388
Name some illnesses with basal ganglia dysfunction
Parkinson’s
Huntingtons
ADHD
Cerebral palsy
Wilson’s (storage disorder)
389
Parkinson’s vs Huntingtons
P - Not enough dopamine
= Increased muscle tone and reduced movement
H - Too much dopamine
= Decreased muscle tone and overshooting movement
390
Synthesis and storage of dopamine
L-Tyrosine = naturally occurring acid
2 enzymatic steps (-> L-DOPA ->)
= dopamine stored in synaptic vesicles cleft and released to 5 different receptors (D1-5)
391
Where exactly is dopamine produced and released?
Dopamine is produced in the substantia nigra and travels along the axon to the synapse in the target (striatum)
392
Why is there not enough dopamine in Parkinson’s?
Not enough dopamine transporters to transport dopamine from substantia nigra to striatum
(Very faint substantia nigra due to dead lewy bodies)
393
Why is there a long presympathetic time phrase for neurogenesis cell deaths (Parkinson)?
2/3 dopamine transporter need to be lost before becoming sympathetic.
(May take decades)
394
Describe huntingtons disease
Larger ventricles due to death of caudate nucleus
395
Functions of cortex vs basal ganglia
Cortex - generates will and motor
BG - fine tuning of movement from c
(C -> BG -> C -> Move)
396
How does substantia nigra and striatum fine tune movements from cortex?
SN - secretes dopamine so signals continue through to cortex
S - secretes GABA which inhibits signal to cortex
(Parkinson’s don’t have SN or dopamine so pauses in signals, Huntingtons is opposite)
397
3 cardinal/clinical features and treatment of Parkinson’s
Brady/Akinesia (slow)
Tremor at rest
Rigidity (may be pain)
Treatment = supply L-DOPA, deep brain stimulation (inactivate subthalamic nucleus so less inhibitory)
398
What 2 functions are dead in Parkinson’s?
Substantia nigra releases dopamine
- This lubricates normal loop
- This stimulates subthalamic nucleus (which inhibits loop)
So PD = Overall inhibition of basal ganglia motor output
399
Clinical features and genetics of Huntingtons
Chorea (overshooting movements)
Dementia/ psychiatric illness
Personality change
Autosomal dominant genetic with full penetrance (tested by looking at repeats of trinucleotides >40)
400
How do we calculate age of onset of Huntingtons
On average more repeats of trinucleotides, the younger the age of onset.
However CANT, because can’t predict for individuals.
