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Yr 2.0 Sem 4 > Nervous System & NeuroPsych 1-5 > Flashcards

Nervous System & NeuroPsych 1-5 Flashcards

(98 cards)

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1
Q

4 Differentiate between the two types of photoreceptors in the retina

A

Rods - low light levels (scotopic vision), BandW, low spatial acuity
Cones - higher light levels, (photopic vision), Colour vision, high spatial acuity

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2
Q

4 List the 8 layers of the retina, deep to surface

A 
(In the New Generation It's Opthalmologists Examining Patient's Retinal epitheiliums) 
Inner limiting membrane
Nerve fibre layer
Ganglion cell layer
Inner plexiform layer
Outer nuclear layer
External limiting membrane
Photoreceptor layer
Retinal pigment epitheilium
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3
Q

4 What is function of the choroid layer of the eye?

A

Vascular supply

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4
Q

4 Why do patients with albinism often have to wear dark glasses?

A

No melanin - which in pigmented layer of retina would normally absorb some light, thus even normal light levels are bright for them, due to glare.

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5
Q

4 What do the horizontal cells of the retina do?

A

Help integrate and regulate the input from multiple photoreceptor cells, facilitating vision in high or low light

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6
Q

4 Which part of the retina is related to the blind spot of vision?

A

Optic disc, where optic nerve enters retina and there are no photoreceptor cells

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7
Q

4 What is amaurosis fugax?

A

Painless temporary loss of vision in one or both eyes

(Latin: fugax meaning fleeting, Greek: amaurosis meaning darkening, dark, or obscure)

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8
Q

4 What is the fovea centralis?

A

Small, central pit in retina composed of closely packed cones and specialized for maximum visual acuity.

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9
Q

4 What type nerve lesion would cause monocular blindness?

A

Unilateral lesion of (ipsilateral) optic nerve

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10
Q

4 What is bitemporal hemianopia?

A

Tunnel vision (as input from nasal fibres lost)

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11
Q

4 What 2 structures are located closest to the optic chiasm?

A

Pituitary gland

Anterior Communicating Artery

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12
Q

4 Name the 5 main components of the visual pathway

A

Optic nerve, optic chiasm, lateral geniculate nucleus, optic radiation and primary visual cortex

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13
Q

4 What are the 2 most common causes of optic nerve lesions in children?

A

Optic nerve glioma or blastoma

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14
Q

4 In what age group are optic sheath meningiomas most common in?

A

Middle aged (mean age at presentation 40 years, also more common in women)

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15
Q

4 Why would damage to the optic chiasm cause “tunnel vision”?

A

Nasal fibres of optic nerves cross over at optic chiasm and so are damaged. These are responsible for the temporal or lateral field of vision. Temporal fibres which give nasal field of vision run laterally so are spared., thus preserving central vision.

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16
Q

4 What’s homonomous hemianopia?

A

When you lose either left or right side of field of vision in both eyes.

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17
Q

4 What is the most common category of cause of homonomous hemianopia?

A

Vascular (i.e. stroke)

[others include neoplasia and trauma]

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18
Q

4 What sight defect would a lesion of the left optic tract cause?

A

Right homonomous hemianopia (loss of R side field of vision in both eyes)

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19
Q

4 What type of sight defects does damgage to optic radiations cause?

A

Quadrantanopias

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20
Q

4 What is the blood supply to the occipital lobe of the brain?

A

◦ Posterior cerebral artery

◦ Middle cerebral artery (occipital pole)

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21
Q

4 Why would central vision be spared in the case of a stroke affecting the posterior cerebral artery?

A

Occipital pole which represents macula is supplied by the middle cerebral artery so will still have adequate blood supply.

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22
Q

4 What are the 3 main things that must happen for our eyes to adjust to see something close up?

A

(3 Cs)
Convergence of eyes
pupillary Constriction
increased Convexity of lens to increase refractive power

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23
Q

4 What are the 3 main muscles required for the accommodation reflex?

A

Medial rectus
Constrictor pupillae
Ciliary Muscle

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24
Q

4 Is the brain involved in the accommodation reflex?

A

Yes (cerebral cortex must be involved)

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25
4 Why does the pupil constrict in the accommodation reflex?
Pupillary constriction allows eye to focus on close objects
26
4 Which arteries supply the anterior and posterior parts of the Circle of Willis?
Internal Carotid Arteries - anterior | Vertebral arteries- posterior
27
4 What is the name of the vessel that completes the Circle of Willis anteriorly?
Anterior communicating artery (links the 2 anterior cerebral arteries)
28
4 Which vessel supplies most of the so-called anterior part (most anterior part of frontal lobe + midline parts of parietal lobes) of the cerebrum?
Anterior cerebral artery
29
5 Why do upper motor nerve lesions affecting the face spare the forehead?
Bilateral innervation of superior part of facial nucleus whereas neurones supplying the rest of the face travel contralaterally. Thus if innervation is lost from one side of the CNS, the forehead is unaffected as it still has functional innervation from the other, unaffected side.
30
5 Where are the cell bodies of lower motor neurons located?
Ventral horn of spinal cord or Cranial nerve motor nuclei in brainstem
31
5 Why does an upper motor neuron lesion cause hyperactivity in the lower motor neuron and muscle supplied?
Net effect of upper motor neurons on lower motor neurons is inhibitory
32
5 Where are the cell bodies of the upper motor neurons found?
Motor cortex i.e. the pre-frontal gyrus
33
5 What is the most common site of an upper motor neuron lesion?
The internal capsule
34
5 Where do upper motor neurons decussate?
In the medulla
35
5 List 5 signs of a lower motor neuron lesion
``` Weakness Areflexia Wasting Hypotonia Fasciulation (Well Aren't We Happy Flappers) ```
36
5 Within which tract do upper motor neurons descend through the spinal cord?
Lateral corticospinal tract
37
5 List the structures through which upper motor neurons descend before reaching the medullary pyramids
Corona radiata Internal Capsule Cerebral peduncle in midbrain Pons
38
5 What do the nerves of the corticobulbar / corticonuclear tract synapse with?
Lower motor neurons in the cranial nerve nuclei (i.e. nerves supplying face)
39
1 What does white matter of the CNS consist of?
Axons and their supporting cells
40
1 Which anatomical landmark of the brain is the primary visual cortex associated with?
Calacrine sulcus
41
1 What function is associated with the parahippocampal gyrus?
Memory encoding (it is the key cortical region for this)
42
1 Where is the cingulate gyrus located?
Curved round the corpus callosum
43
1 Which type of CNS tissue is more vascular?
Grey matter
44
*1st yr* 1 How does the neural tube of the embryo develop?
Gastrulation produces notocord. Notocord induces neurulation in overlying ectoderm. Neural plate forms and its lateral edges elevate becoming the neural folds between which is the neural groove. Neural folds approach each other in the midline, fusing to form neural tube.
45
1 At what point of embryonic development does the neural tube become completely closed?
By day 28-32
46
1 What is the most common site of a spina bifida?
Lumbosacral region
47
1 What would a failure of the neural tube to close cranially cause?
Ancephaly (this is incompatible with life)
48
1 What is rachischisis?
Severe form of spina bifida resulting from failure of neural fold elevation (almost always fatal)
49
1 What advice is given to help prevent neural tube defects?
That all women of childbearing age / that are trying to conceive take folic acid supplements (3 months pre-conceptually + during 1st trimester)
50
1 What maternal blood test can be used to detect neural tube defects in a developing foetus?
Serum alpha fetoprotein - this will be raised in NTD
51
1 Explain why the cauda equina forms embryologically
Vertebral column grows faster than spinal cord after 3rd month of development. Spinal roots must therefore elongate because they still exit at their inter-vertebral foramen.
52
1 When do the secondary embryological brain vesicles form?
At 5 weeks (primary form during 4th week)
53
1 Name the 5 secondary embryological brain vesicles and state which structures they become in the adult brain
``` Telencephalon - Cerebral hemispheres Diencephalon - Thalamus Mesencephalon - Midbrain Metencephalon - Pons and cerebellum Myelencephalon - Medulla oblongata ```
54
1 Name the 2 flexures of the brain
Cervical and cephalic
55
1 What is neonatal hydrocephalus most commonly associated with?
Spina bifida (also aquaductal stenosis)
56
1 What are neural crest cells?
Cells of lateral border of the neuroectoderm tube which migrate into mesoderm and become mesenchymal
57
1 What causes Hirshsprung's disease?
Defect in neural crest migration affecting colon
58
1 Which components of the endocrine system are neural crest derivatives?
C cells of thyroid gland | Adrenal medulla
59
1 Why can maternal alcoholism affect the developing embryological heart?
Alcohol disrupts neural crest migration | Conotruncal septum which divides the outflow region of the developing heart is a neural crest derivative
60
1 Briefly describe diGeorge syndrome
(CATCH 22) Cardiac (aortic arch anomalies, conotruncal (TOF, truncus arterious, interrupted aorta), tricuspid atresia) Abnormal facies (hypertelorism, ear anomalies, short down slanting palpebral fissures (antimongoloid), short philtrum) Thymic hypoplasia (cellular immune deficiency: abnormal number and function of T-cells) Cellular immune deficiency; Cleft palate Hypoparathyroid w/ Hypocalcemia (causes tetany) 22 chrom defect (deletion 22q11; dx by FISH)
61
2 What is the most abundant type of glial cell?
Astrocytes
62
2 What is the function of microglia?
Immune response - phagocytose debris and foreign material
63
2 How are neurones supplied with energy if blood glucose is low?
Astrocytes produce lactate which is transferred to neurones via the glucose lactate shuttle
64
2 How do astrocytes help maintain a favourable environment for neurones?
Uptake neurotransmitters, including glutamate which becomes toxic at high concentrations Take up K+ to maintain ionic environment
65
2 Differentiate between oligodendrocytes and Schwann cells
Oligodendrocytes secrete myelin sheaths around multiple axons of the CNS Schwann cells wrap themselves around single axons in the PNS and phagocytose foreign material
66
2 What 3 features of brain capillaries and other local cells contribute to the blood brain barrier?
Tight junctions between endothelial cells Basement membrane surrounding capillary End feet of astrocyte processes
67
2 Name the 3 chemical classes of neurotransmitters
Amino acids Biogenic amines Peptides
68
2 What is the major excitatory neurotransmitter?
Glutamate
69
2 Name the 2 main inhibitory amino acid neurotransmitters
GABA (brain) | Glycine (mostly brainstem and spinal cord)
70
2 Which ions are NMDA receptors permeable to?
Na+ K+ and Ca2+
71
2 How does activation of GABA and glycine receptors decrease action potential firing?
Integral Cl- channels open, Cl- enters cell causing hyperpolarisation after which a greater change in membrane potential is needed for action potentials so these occur less readily.
72
2 Name 2 classes of drugs that bind to GABA receptors
Barbiturates | Benzodiazepines
73
2 Which neurotransmitter do inhibitory inter-neurones in the spinal cord release?
Glycine
74
2 Where does acetylcholine act in the peripheral nervous system?
Neuromuscular junctions Autonomic ganglion synapses Synapses of parasympathetic post-ganglionic neurons w/ their target tissues
75
2 What functions are the cholinergic pathways of the CNS involved in?
Arousal, learning, | memory and motor control
76
2 Why are cholinesterase inhibitors used to alleviate symptoms of Alzheimer's disease?
Alzheimers causes degeneration of cholinergic neurones (in the nucleus basalis) -> ACh depletion. Cholinesterase catalyses breakdown of ACh thus when inhibited ACh conc. will increase.
77
2 Which dopaminergic pathway is involved with motor control?
Nigrostriatal
78
2 What are the mesocortical and mesolimbic pathways of the brain involved in?
Mood, arousal and reward
79
2 Loss of which neurones are associated with Parkinson’s disease?
Dopaminergic neurones of the substantia nigra
80
2 What is the mechanism of action of most antipsychotics?
Antagonism at dopamine D2 | receptors
81
2 How is action in the peripheries prevented in dopamine therapy?
Give precursor L-DOPA combined with Carbidopa which inhibits the enzyme that converts L-DOPA to dopamine but cannot cross the blood brain barrier and so only acts peripherally.
82
2 How does L-DOPA cross the blood-brain barrier?
Through large neutral amino acid transporter
83
2 What are the 2 main functions of serotonergic pathways in the CNS?
Regulating sleep/wakefulness and mood
84
2 What receptors would you find at glutamatergic synapses?
AMPA and NMDA receptors
85
2 What receptors does noradrenaline act on?
G protein coupled alpha and beta adrenoreceptors
86
2 Where are the cell bodies of noradrenaline containing neurones located?
Pons and medulla i.e. brainstem
87
2 Where does most noradrenaline in the brain come from?
Locus ceruleus in brainstem
88
3 What modalities of sensation are innervated by the spinothalamic system?
Temperature Pain Crude touch (including pressure and stretch)
89
3 Where are the cell bodies of primary sensory neurones located?
Dorsal Root Ganglion the spinal cord
90
3 Where would you find the axons of neurons that detect vibration, proprioception and fine touch?
Dorsal column of spinal cord
91
3 Explain why there are not clear borders between dermatomes
Each neuron receives input from multiple receptors, known as its receptive field. These often overlap so that one area of skin may be supplied by 2 different neurons.
92
3 At what level does the sensory system decussate?
Secondary sensory neurons are the ones that decussate. Their cell bodies are located in dorsal horn or medulla.
93
3 Describe the general route of tertiary sensory neurons
From thalamus, where their cell bodies are, to the primary sensory cortex i.e. the post central gyrus
94
3 Why would a central cord lesion affect different modalities of sensation differently?
The 2 systems that each supply a different set of sensory modalities are organised differently in the spinal cord. In the dorsal column pathway (fine touch, vibration and proprioception) the lower body maps to the medial portion of the tract while in the spinothalamic tract (temperature, pain, crude touch and presssure) the lower body maps to the more lateral, superficial parts.
95
3 Name the 2 nuclei whose axons form the medial lemiscus pathway
Gracile and Cuneate (both synapse with dorsal column pathway)
96
3 Why does activation of mechanoreceptors alleviate pain?
It excites inhibitory enkephalinergic interneurones in the spinal cord
97
3 Which nerve fibres are responsible for slow, diffuse, dull pain?
C fibres (unmyelinated)
98
3 What causes Brown-Sequard syndrome?
Complete hemisection of spinal cord due to trauma or ischaemia (rare)

Yr 2.0 Sem 4 (4 decks)

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