Neuro 2 Flashcards
1
Q
Where are the sympathetic cell bodies located?
A
T1-L2 spinal ganglia
2
Q
What does the sympathetic NS used as preganglionic neurotransmitter & what is the receptor for this?
A
ACh
Nicotinic cholinergic receptors
3
Q
What does the sympathetic NS used as postganglionic neurotransmitter & what is the receptor for this?
A
Adrenaline
Adrenergic
4
Q
Where are the parasympathetic cell bodies located?
A
Sensory ganglia of cranial nerves 3,7,9,10 & spinal nerve ganglia S2-S4
5
Q
What does the parasympathetic NS use as its preganglionic & postganglionic neurotransmitter and what are the receptors for this?
A
ACh
Cholinergic
Pre = nicotinic cholinergic
Post = muscarinic cholinergic
6
Q
What are the 3 main types of neurones?
A
Unipolar - cell body as projection from axon
Bipolar - cell bodies in middle of axon
Multipolar - cell bodies in centre of dendrites
7
Q
What are the 3 functional types of neurons?
A
Afferent - sensory to CNS
Efferent - CNS to tissues
Interneurons - within CNS
8
Q
What is the CNS myelinated by?
A
Oligodendrocytes (type of glial cell)
9
Q
What is the PNS myelinated by?
A
Schwann cells
10
Q
What is the purpose of myelination?
A
Acts as insulating later to prevent movement of Na+ & K+ across axon
Nodes of Ranvier act to propagate action potential faster by saltatory conduction
11
Q
What moves substances along an axon?
What are the 2 proteins involved in transport & in which direction do they move substances?
A
Microtubules & proteins
Microtubules made from proteins
Kinesins - transport substances away from cell body (anterograde transport)
Dyneins - transport substances towards cell body (retrograde transport)
12
Q
What are the 4 main types of glial cell?
A
Oligodendrocytes - myelination of CNS
Astrocytes - BBB, role in control of brain ECF composition, metabolically support neutrons
Microglia - macrophage like
Ependymal cells - line ventricles & regulate production of CSF
13
Q
What is the refractory period of an action potential?
A
The period immediately following stimulation during which a nerve or muscle is unresponsive to further stimulation due to Na+ channels already being open
14
Q
What is the purpose of a refractory period?
A
To insure the impulse travels in only 1 direction
15
Q
What is the speed of an action potential determined by?
A
Axon diameter
Myelination
16
Q
What are the 2 structures of the external ear?
A
Auricle
External acoustic meatus
17
Q
Where does the middle ear lie?
A
Within the temporal bone
18
Q
What are the 4 main parts to the middle ear?
A
Tympanic membrane
Auditory ossicles - malleus, incus, stapes
Muscles (contract to protect from loud noises) - tensor tympani, stapedius
Auditory tube - middle ear to nasopharynx, equates pressure
19
Q
What is the tensor tympani innervated by?
A
Mandibular, CNV3
20
Q
What is the stapedius innervated by?
A
Facial, CNVII
21
Q
Where does the inner ear lie?
A
Within the petrous part of the temporal bone
22
Q
What are the 3 main parts of the inner ear?
A
Bony labyrinth - bone cavities filled with perilymph
Membranous labyrinth - ducts within bony filled with endolymph
Oval window
23
Q
What are the 3 parts of the bony labyrinth?
A
Vestibule - central part
Cochlea - houses cochlear duct
Semicircular canals - contain semicircular ducts
24
Q
What does the spiral lamina do?
A
Projection from centre of cochlea that divides cochlea into 2 chambers
Scala vestibuli superiorly
Scala tympani inferiorly
25
What are the 2 parts of the membranous labyrinth?
Vestibular system - semicircular ducts, saccule, utricle
| Cochlear duct
26
What is the purposes of the organ of Corti?
Conversion of pressure changes in cochlea into electrical impulses sent to the brain
27
What are the differences between the region of the cochlear duct that experiences maximum displacement according to frequency?
Higher - vibration of part closest to oval window
| Lower - vibrations travel further along scala vestibule & vibrate more distal sections
28
What are the hair cells?
Mechanoreceptor cells that have hair-like projections from the top of them (stereocilia)
29
How do vibrations cause an electrical impulse?
* Stereocilia in contact with tectorial membrane that overlies organ of Corti & remains stationary during vibrations
* Pressure waves cause displacement of basilar membrane
* Hair cells move & sterocilia bend
* Tip links between ends stretched
* Physically opens mechanically-gated ion channels
* Influx of K+ (surrounding endolymph is K+ rich)
* Depolarisation
* Voltage gated Ca2+ channels near base open
* Glutamate released into space between hair cell & afferent neutron fibres
* Form cochlear branch of CNVIII
30
What is the auditory pathway?
Internal acoustic meatus > ipsilateral cochlear nucleus complex > trapezoid body > contralateral superior olivary nucleus > lateral lemniscus > inferior colliculus > medial geniculate body > primary auditory cortex
I'M AUDITORY
31
How do the semicircular canals detect acceleration?
The canals move & the endolymph doesn't
Inside surface of canals move against fluid
Bending of sterocilia
Stimulation of afferent neurons
32
What are the sterocilia in the semicircular canals ensheafed by?
Cupula, a gelatinous mass
33
What makes the hair cells more easily subject to gravity in the utricle & saccule?
Calcium carbonate crystals, otoliths
34
What 3 nuclei make up the vestibular nuclei?
Medial - semicircular canal
Superior - semicircular canal
Lateral - utricle & saccule
35
What is the function of the basal ganglia?
Controls movements by facilitating & inhibiting
36
What do the direct & indirect pathways do?
Direct - make & maintain movements
| Indirect - inhibits & prevents movements
37
What are 2 disorders of the basal ganglia?
Parkinson's disease (not enough dopamine)
| Huntington's disease (too much dopamine)
38
What is a motor end plate?
A region of muscle fibre's plasma membrane that lies directly beneath an axon's terminal plasma membrane
39
What is a neuromuscular junction?
Junction of axon terminal & motor end plate
40
What is the difference between synapses & NMJs?
All action potentials in motor neurone usually trigger an AP in muscle fibres
All NMJs are excitatory
41
What extra-ocular muscles originate from the common tendinous ring?
Rectus x4
| Superior oblique
42
What are the 4 stages of an action potential?
1) resting potential = Na+/K+atpase pump pumps 3Na+ out & 2K+ in; some K+ diffuses out
2) depolarisation = stimulus causes some Na+ channels to open; Na+ influx
3) repolarisation = some K+ channels open & Na+ channels close; K+ diffuse out
4) hyperpolarisation = K+ slow to close; overshoot; helps refractory period
43
What is a synapse?
A junction between 2 neurons where the electrical activity in the presynaptic neuron influences the activity in the post-synaptic neuron
44
What are the 2 types of synapse?
Chemical - excitatory, inhibitory, modulatory
| Electrical
45
What is convergence? (synapse)
Many presynaptic neurons influencing one postsynaptic neuron
46
What is divergence? (synapse)
One presynaptic neurone influences many postsynaptic neuron
47
What are the 7 stages of transmission across a synapse?
1) AP depolarises pre-synaptic axon terminal membrane
2) Na+ voltage-gated channels open & influx
3) Ca2+ channels open & influx
4) synaptic vesicles fuse with presynaptic axon terminal & release contents by exocytosis
5) neurotransmitters in synaptic cleft & diffuse across
6) bind to receptor proteins on post-
7) ligand gated ion channels open & propagate AP
48
What are 3 ways of neurotransmitter termination?
Reuptake by astrocyes/presynaptic terminal
Destroyed by enzymes
Diffuse away from site
49
What are glutamate & GABA in the brain?
Neurotransmitters
Glutamate - excitatory
GABA - inhibitory
50
What is the definition of pain?
An unpleasant sensory & emotional experience associated with actual or potential tissue damage
51
Define referred pain
Sensation of pain is experienced elsewhere to where the stimulus is
52
What are 2 classifications of pain relating to time?
```
Acute = <12 weeks, typical
Chronic = >12 weeks, longer than expected for stimulus
```
53
What are the 2 types of chronic pain?
Cancer
| Non-cancer
54
What are 2 other classifications of pain?
```
Neuropathic = pain caused by damage/disease affecting somatosensory NS
Nociceptive = pain caused by stimulus damaging tissues that is detected by nociceptors, non-neural tissue
```
55
What is the method of feeling pain?
* Nociceptors stimulated in an injury
* Tissue damage releases bradykinin & prostaglandin E2, which reduce the nociceptive threshold & increases sensitivity to stimuli
* Nociceptor afferent nerves release substance P, a neurotransmitter that causes long lasting excitatory post-synaptic potential to help sustain the effect of noxious stimuli
56
Where does the process of pain begin & what tracts does it involve?
Dorsal horns
| Lateral spinothalamic tracts
57
What is a nociceptor?
A sensory neutron found in any tissue capable of experiencing the sensation of pain
58
What is analgesia?
Selective suppression of pain without any effect on consciousness
eg paracetamol
Doesn't eliminate sensation
59
What is an anaesthetic?
Substances which induce insensitivity to pain
| Reversible loss of sensation
60
What are the differences between A delta and C fibres?
A delta - mechanical & thermal; thinly myelinated; larger diameter; sharp acute specific pain; faster
C - mechanical & thermal & chemical; non-myelinated; smaller diameter; diffused dull later pain; slower; 70% of nociceptive fibres
61
What is periaqueductal grey?
Grey matter around the cerebral aqueduct
Receives input from cortical & sub-cortical areas
Modulates afferent noxious transmission
Primary control centre for descending pain modulation
Has opioid receptors - can result in analgesia
62
What is the area postrema?
Part of medulla outside BBB
Can detect toxins & act as vomit inducing centre
Densely vascularised without tight junctions
63
What is the Melzack-Wall pain gate theory?
Non-painful input closes the 'gates' to painful input which therefore prevents pain sensation from travelling to the CNS
eg massage, ice packs
64
Where are the 4 main areas of pain recognition?
Thalamus
Somatosensory cortex
Insula cortex (in lateral sulcus, judges degrees of pain, subjective)
Periaqueductual grey
65
How do opoids produce their effects?
Occupy receptors on pre-synaptic neurones to cause an inhibitory membrane potential & prevent the release of substance P
66
What are endorphins?
Naturally occurring peptides that have opiate like effects
67
What is substance P
Neurotransmitter used for transmission of pain information into CNS
68
What is a motor unit?
A single alpha neutron & all of the muscle fibres it innervates
69
What is a motor neurone pool?
A collection of motor neurone innervating a single skeletal muscle
70
What does a golgi tendon detect?
Changes in muscle tension
71
What are golgi tendons innervated by & what are they made of?
Sensory 1b neurons
| Network of collagen fibres inside a connective tissue capsule
72
What does a muscle spindle detect?
Stretch of a muscle
73
What are muscle spindles innervated by & what are they made of?
Sensory 1a neurons
| Intrafusal fibres
74
What is Brown-Sequard syndrome?
Hemisection of spinal cord
75
What are the symptoms of Brown-Sequard syndrome?
Loss of contralateral pain & temperature (spinothalamic)
| Loss of ipsilateral motor & fine touch (descending motor tracts, DCML)
76
What is the visual pathway?
Eyes > optic nerve > optic chasm > optic tract > lateral geniculate nuclei > optic radiations > primary visual cortex
77
Which visual fields cross over?
Nasal
78
What is Meyer's loop
Travels inferiorly to Baum's loop through temporal lobe
| Carries information from inferior retina (superior visual field)
79
What lies within the outer eye? (2)
Cornea (clear, protective, refraction)
| Sclera (tough, attachment for muscles)
80
What lies within the middle eye? (3)
```
Iris (pupil)
Ciliary body (produces aqueous humour, alters shape of lens)
Choroid plexus (blood supply)
```
81
What lies within the inner eye? (1)
Retina (transduction of light)
82
What are the 10 layers of the retina from superficial to deep?
1) internal limiting membrane
2) nerve fibre (axon of ganglions)
3) ganglion cell
4) inner plexiform
5) inner nuclear
6) outer plexiform
7) outer nuclear
8) external limiting membrane
9) photoreceptor
10) retinal pigment epithelium
83
What are the differences between rod & cone cells?
Rods - light, more abundant, better sensitivity
| Cones - colour & visual acuity
84
What is the levator palpebral superioris innervated by?
Oculomotor CNIII
85
What is the purpose of the round window of the ear?
Allows fluid in the cochlea to move
86
What are the 3 scala of the middle ear?
Scala media
Scala tympani
Scala vestibuli
87
What are the differences between inner and outer hair cells?
```
Inner = one row, afferent fibres, transmit auditory stimuli
Outer = more numerous, 2/3 rows, efferent fibres, modulate inner hair cells
```
88
What are the 7 main parts of the basal ganglia?
```
Putamen
Subthalamic nucleus
Substantia nigra
Hypothalamus
Globus pallidus (madia & lateral)
Thalamus
Caudate nucleus
```
89
What does the striatum do?
Caudate & putamen
Main target input of basal ganglia
Releases GABA
Inhibitory (rostral)
90
What is the lentiform nucleus made up of?
Globus pallidus & putamen
91
What does the globus pallid us do?
Output source to thalamus
92
What does the subthalamic nucleus do?
Communicates with globus pallidus
| Caudal
93
What does the substantia nigra do?
In tegmenjtum
Releases dopamine
Caudal (excitatory)
94
What are the 7 main parts of the limbic system?
```
Cingulate gyrus
Thalamus
Fornix
Hypothalamus
Mamillary body
Hippocampus
Amgdala
```
95
What is the Papez circuit?
Neural circuit for the control of emotional expression
96
What are the components of the Papez circuit?
Hippocampal formation → fornix → mammillary bodies → anterior thalamic nucleus → cingulum → hippocampal formation
97
What is the fornix?
Pathway of nerve fibres that transmit information from hippocampus to mamillary body
98
What is the role of the hippocampus?
Involved in learning, memory & recollection of spatial relationships
99
What is the role of the parahippocampal gyrus?
Helps modify expression of emotions
100
What is the role of the amygdala?
Influences behaviour & fear
101
What is the mamillary body?
Tiny nucleus acting a a relay station of information from the fornix to the thalamus
102
What are the 4 cerebellar nuclei?
Dentate
Emboliform
Globose
Fastigi
103
What is the role of the cerebellum?
Coordinates voluntary movement
Balance
Equilibrium
Muscle tone
104
What connects the cerebellum to the midbrain?
Peduncles
105
What are the 3 lobes of the cerebellum?
Anterior
Posterior
Floculonodular
106
What are the fissures of the cerebellum?
Primary - between anterior & posterior
Horizontal - makes lateral & posterior margins of hemisphere
Posterolateral - between floculonodular & posterior
107
What joins the hemispheres of the cerebellum at the midline?
Vermis
108
What are the functional divisions of the cerebellum?
Cerebrocerebellum (neocerebellum
Spinocerebellum (paleocerebellum)
Vestibulocerebellum (archicerebellum)
109
What does the cerebrocerebellum do, is made up of & inputs from?
Planning movements, motor learning, trajectory
Lateral hemispheres
Input from pons via peduncle
110
What does the spinocerebellum do, is made up of & inputs from?
Regulating body movement, muscle tone, posture
Vermis
Spinocerebellar tracts via peduncles
111
What does the vestibulocerebellum do, is made up of & inputs from?
Controlling balance & ocular reflexes
Flocculonodular lobe & fastigi nuclei
Input from vestibular nuclei via peduncles
112
What are the 3 arteries that supply the cerebellum?
Superior cerebellar
Anterior inferior cerebellar
Posterior inferior cerebellar
113
What are the 3 peduncles?
Superior - midbrain
Middle - pons
Inferior - medulla
114
What are the 3 layers of the cerebellar cortex from superficial to deep?
Molecular
Purkinje
Granule
115
What are the 2 inputs to the cerebellar cortex?
Mossy fibres - from middle peduncle, inform of voluntary motor input, synapse with granule cells, have parallel fibres
Climbing fibres - from inferior peduncle, convey muscle proprioception & vestibular inputs
116
What is the output from the cerebellar cortex?
Purkinje cell axons - from dentate nucleus > superior peduncle > thalamus
117
What are the symptoms for cerebellar damage?
```
'DANISH'
Dysmetria (inability to judge distance)
Ataxia (staggering)
Nystagmus (abnormal eye movements)
Intention tremor
Slurred speech
Hypotonia (weak muscles)
```
118
What are the 3 primary brain vesicles?
Prosencephalon (forebrain)
Mesencephalon (midbrain)
Rhombencephalon (hindbrain)
119
What are the 5 secondary brain vesicles?
Pros -> telencephalon & diencephalon
Mes -> mesencephalon
Rhomb -> metencephalon & myelencephalon
120
What do each of the primary brain vesicles from?
Pros - cerebrum; thalamus
Mes - midbrain
Rhomb - cerebellum & pons; medulla
