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Phase 1 > Nervous System > Flashcards

Nervous System Flashcards

1
Q

what is the definition of a neurone? (2)

A
  • functional unit of the nervous system

* consists of a cell body, dendrites (receive signal) and axons (transmit signal)

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2
Q

what is the definition of a nucleus (in terms of nervous system?

A

groups of neurones located in a specific region - generally have similar appearances and functions

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3
Q

what is the definition of a tract?

A

many axons grouped together, common region / target

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4
Q

what is white matter?

A

region of the brain / spinal cord with increased density of myelinated axons

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5
Q

what is grey matter?

A

region of the brain / spinal cord with an increased density of cell bodies and less myelination

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6
Q

what are glial cells?

A

non-neural cells (different types)

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7
Q

what is the CNS? what is the PNS?

A

CNS - brain and spinal cord

PNS - peripheral, nerves outside of CNS

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8
Q

what is the definition of nerve ganglion?

A

group of nerve cell bodies located outside the CNS

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9
Q

what are the main types of glial cells and what are their functions? (5)

A
  • astrocytes - form blood-brain barrier, regulate neurotransmitters, regulate blood flow to brain, homeostasis
  • oligodendrocytes - myelinate axons in the CNS
  • microglia - immune protection of the brain (inflammation)
  • ependymal cells - make up ependymal membrane
  • Schwann cells - myelinate axons in the PNS
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10
Q

what is the cerebral cortex?

A
  • outer layer of the cerebrum

* covers the outside and also contains deeper structures (eg. basal ganglia, limbus system)

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11
Q

what surface features define the lobes of the cerebral cortex?

A
  • sucli - grooves

* gyri - ridges

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12
Q

what 4 areas are included in the frontal lobe? what are their functions?

A
  • pre-frontal cortex: higher level cognition (behaviour, personality)
  • primary motor cortex
  • olfactory bulb: sends smell information to amygdala
  • Broca’s area: speech production
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13
Q

what structure separated the frontal lobe from the parietal lobe?

A

central sulcus

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14
Q

what 3 areas included in the parietal lobe? what are their functions?

A
  • primary somatosensory cortex: receives sensory information from the thalamus
  • gustatory cortex: perception of taste
  • posterior parietal cortex: planned movements and spatial reasoning
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15
Q

what 3 areas are included in the temporal lobe? what are their functions?

A
  • auditory cortex: interpretation of auditory information
  • fusiform face area: facial recognition
  • Wernicke’s area: comprehension of written and spoken language
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16
Q

what area is found in the occipital lobe? what is its function?

A

primary visual cortex: interpretation of visual information

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17
Q

what are 5 important structures found deep in the cerebral cortex? what are their functions?

A
  • hypothalamus: control of the autonomic nervous system - body temperature, blood pressure, hormone secretion
  • pituitary gland: connected to the hypothalamus, ‘master gland’ - control other endocrine glands
  • thalamus: relay station for almost all sensory information
  • basal ganglia: fine motor control
  • limbic system: emotions, learning and memory (includes amygdala and hippocampus)
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18
Q

what is the function of the cerebellum?

A

balance, posture and coordination of movement

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19
Q

what is the structure of the brain stem (superior to inferior)? what are the functions of the brainstem?

A
  • midbrain - pons - medulla oblongata

* regulates cardiac and respiratory function (heart rate / breathing rate)

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20
Q

what are the 3 layers of the meninges, and in what order are they found (superficial to deep)?

A
  • dura mater - hard
  • arachnoid mater - spider
  • pia mater - gentle
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21
Q

where are the epidural and subdural potential spaces found? why are they potential spaces?

A
  • epidural: between dura and skull
  • subdural: between dura and arachnoid
  • only becomes space when filled with fluid (eg. haematoma)
22
Q

where is the subarachnoid space found? what are its features?

A
  • between arachnoid and pia
  • connected with arachnoid trabeculae
  • filled with cerebrospinal fluid
23
Q

where is cerebrospinal fluid found? what are its general functions?

A

• fills ventricles and subarachnoid space

  • cushions brain
  • allows brain to be suspended within the skull
  • provides a stable chemical environment
  • nutrient and waste exchange between nervous tissue and blood
24
Q

what is the choroid plexus?

A

region within each ventricle where CSF is produced

25
Q

where is CSF reabsorbed into the blood?

A
  • arachnoid granulations

* protrusions of dura into the dura venous sinuses (channel for venous blood in dura mater)

26
Q

what are the 3 aspects involved with separating blood and brain tissue?

A
  • endothelial cells lining capillary wall - tight junctions
  • astrocyte processes surrounding the vessel to provide biochemical support
  • capillary basement membrane
27
Q

what are the differences between blood plasma and CSF? (2)

A
  • CSF has less protein content

* different electrolyte levels to maintain ionic environment of the brain

28
Q

describe the blood-CSF barrier (3)

A
  • controls the composition of CFS
  • unlike rest of brain tissue, choroidal capillaries have no tight junctions - leaky gaps (large molecules CAN pass though ENDOthelium)
  • outer layer of choroid plexus is made up of EPIthelium that does have tight junctions - specialised ependymal cells act as filter
29
Q

what are 2 reasons why some parts of the blood-brain barrier have increased permeability?

A
  • sensory functions (eg. toxin detection to initiate vomiting reflex)
  • secretory functions (pituitary gland)
30
Q

what is the definition of meningitis?

A

the inflammation of the meninges, mostly caused by bacterial, viral or fungal infection

31
Q

what is the difference between encephalitis and meningitis (in terms of invasion of the brain)

A
  • encephalitis is invasion across the blood-brain barrier

* meningitis is invasion across the blood-CFS barrier

32
Q

what are 3 methods that pathogens might use to cross the blood-CFS barrier?

A
  • infecting cells making up the barrier - ependymal cells
  • passive transfer through intracellular vacuoles
  • carried across in infected white blood cells
33
Q

why is inflammation more dangerous in the brain than in other tissues?

A

•enclosed box of the skull, therefore pressure builds up quicker and is more threatening to brain structures

34
Q

what are the 3 most common causes of bacterial meningitis? describe their characteristics

A
  • Haemophilius influenzae - usually very young patients without vaccination (G- coccobacillus)
  • Neisseria meningitidus - meningococcal disease (G- diplococcus)
  • Streptococcus pneumoniae - pneumococcal disease (G+ diplococcus)
35
Q

what are the common virulence factors between bacterial agents of meningitis?

A
  • polysaccharide capsule (important in vaccines)

* proteases that breakdown IgA - defenders at entry portals

36
Q

where in the meninges does inflammation occur during acute meningitis?

A

subarachnoid space

37
Q

describe the pathogenesis of acute meningitis, including inflammation progression (6)

A

1 - invasion of the CNS is detected by astrocytes and microglia
2 - release cytokines which increase in BBB permeability
3 - causes vasogenic cerebral oedema (leakage into extracellular brain tissue from BVs)
4 - increased presence of WBCs in CSF causing inflammation of the meninges (increased pressure)
5 - endothelial cells of BVs also become inflamed and accumulate fluid
6 - blood flow to brain is reduced leading to a lack of oxygen and death of brain issue

38
Q

what are the signs of meningitis? what symptom is characteristic of meningococcal meningitis?

A
  • generic - sore throat, headache and drowsiness
  • meningitis - fever, irritability, neck stiffness, photophobia

• meningococcal - haemorrhagic skin rash with purple spots (petechiae), non-blanching (indicative of septicaemia due to high circulating bacteria levels)

39
Q

what is the mortality rate of meningococcal meningitis with and without treatment?

A
  • without - 100%

* with - 10%

40
Q

what triad of symptoms are indicative of meningitic syndrome? what 2 symptoms are also commonly seen?

A
  • headache, neck stiffness and fever

* photophobia and vomiting

41
Q

what is a +ve Kernig’s test (bare in mind this is not always reliable)

A

increased pain with hip and neck flexion, relief with knew flexion (meninges irritation)

42
Q

why is initial treatment of suspected meningitis empiric?

A

• so life-threatening that treatment must begin as soon as possible even if the cause is not known

43
Q

what 2 diagnostic tests are used with suspected bacterial meningitis?

A
  • blood cultures - Gram stained, blood count and inflammatory markers
  • lumbar puncture (may not always be necessary but is a conclusive test) - shows decreased glucose, increased protein, increased neutrophil count than normal CSF
44
Q

why is a CT / MRI performed before a lumbar puncture?

A

• check for intercranial pressure -> LP can cause herniation

45
Q

describe how a lumbar puncture is performed?

A
  • needle inserted into spinal canal -> within vertical foremen of the vertebrae
  • performed under local anaesthesia, iodine to sterilise
  • access subarachnoid space of the spinal cord (may use ultrasound for precision)
  • hypodermic needle is inserted between L3/4, L4/5 or L5/S1 (roughly level of the cords equina)
46
Q

what is the main antibiotic used to treat bacterial meningitis? what type of antibiotic is it, and how does it work?

A
  • Ceftriaxone
  • beta-lactam
  • selectively inhibits bacterial wall synthesis by binding to transpeptidases (penicillin-binding proteins)
47
Q

what prophylaxis treatment can be used on close contacts of those with meningococcal meningitis? what type of antibiotic is it and how does it work?

A
  • Ciprofloxacin
  • fluoroquinolone class
  • separate bacterial DNA strands
48
Q

what is the difference between broad spectrum and narrow spectrum antibiotics?

A
  • broad spectrum act against a wider range of bacteria

* narrow spectrum target a particular group of bacteria

49
Q

what are the features and mode of action for beta-lactams? (4) what are 2 examples of sub-classes within beta-lactams?

A
  • bactericidal
  • have a beta-lactam ring (3 carbon, 1 nitrogen square shape)
  • inhibit synthesis of peptidoglycan layer of bacterial cell wall
  • bind to penicillin bind proteins (PBP) to irreversibly inhibit cross-linking of the peptidoglycan layer

• penicillins + cephalosporins (Ceftriaxone)

50
Q

what are the features and mode of actions for fluoroquinolone class antibiotics? (3)

A
  • broad spectrum
  • bacteriocidal
  • interfere with DNA replication by inhibiting ligase
51
Q

what are the most common permanent complications of bacterial meningitis? (7)

A
  • hearing loss
  • epilepsy
  • memory / concentration problems
  • coordination / movement / balance problems
  • learning difficulties
  • behavioural problems
  • vision loss

Phase 1 (14 decks)

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