Basic neurophysiology Flashcards

1
Q

Intracellular resting membrane potential

A

-70mV

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2
Q

Intracellular threshold potential

A

-55mV

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3
Q

Channels that open at the intracellular threshold potential of -55mV

A

Na+ channels

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4
Q

Result of the Na+ influx caused by Na+ channels opening

A

Reversal of the membrane potential to +40mV

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5
Q

Effect of the membrane potential reaching +40mV

A

Na+ channels close
Voltage gated K+ channels open
K+ ions move out of the axon
Cell membrane is repolarised

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6
Q

Term for a junction between two nerve cells

A

Synapse

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7
Q

Three types of synapses in the nervous system

A

Chemical synapse
Electrical synapse
Conjoint synapse

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8
Q

Features of a chemical synapse

A

Presynaptic neuron is stimulated and releases a chemical molecule
Molecule acts on the postsynaptic neuron to produce an effect, or to carry the impulse further along to a further neuron

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9
Q

Types of chemical synapse depending on their effect on the postsynaptic neuron

A

Excitatory

Inhibitory

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10
Q

Effect of excitatory chemical synapses on postsynaptic neurons

A

Depolarises

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11
Q

Effect of inhibitory chemical synapses on postsynaptic neurons

A

Hyperpolarises

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12
Q

Process where a postsynaptic depolarisation is not enough by itself to induce an action potential in the cell, but with further stimulation an action potential can be generated

A

Facilitation

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13
Q

Type of facilitation where input from several different presynaptic cells leads to an action potential

A

Spatial summation

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14
Q

Type of facilitation where recurrent stimulation from the same presynaptic neuron results in an action potential

A

Temporal summation

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15
Q

Features of an electrical synapse

A

Response is generated by electrical communication without the need for chemical molecules to be exchanged

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16
Q

Features of a conjoint synapse

A

Both electrical and chemical properties

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17
Q

Part of the body which acts as the satiety centre

A

Ventromedial hypothalamus

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18
Q

Part of the body which acts as the feeding centre

A

Lateral hypothalamus

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19
Q

Neurochemicals which cause increased appetite

A

Ghrelin

Neuropeptide Y

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20
Q

Neurochemicals which decrease appetite

A

Leptin
Cholecystokinin
Serotonin

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21
Q

Part of the body where ghrelin is synthesised

A

Gastric mucosa

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22
Q

Cells which synthesise ghrelin

A

Adipose cells

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23
Q

Part of the body where activity is increased by food and food cues

A

Nucleus accumbens

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24
Q

Type of activity produced in the nucleus accumbens by food and food cues

A

Dopaminergic activity

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25
Q

Part of the body which acts as the hypothermic centre

A

Preoptic anterior hypothalamus

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26
Q

Part of the body which acts as the hyperthermic centre

A

Posterior hypothalamus

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27
Q

Effects of stimulating the preoptic anterior hypothalamus

A

Sweating
Vasodilation
Hyothermia

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28
Q

Effects of stimulating the posterior hypothalamus

A

Shivers
Vasoconstriction
Hyperthermia

29
Q

Part of the body where lesions can interrupt normal diurnal temperature variation

A

Median eminence (a midline swelling on the inferior surface of the hypothalamus)

30
Q

Cause of malignant hyperthermia caused by drugs

A

Abnormal excitation-contraction in skeletal muscles

31
Q

Part of the brain which is involved in pain perception

A

Thalamus

32
Q

Types of fibres which carry pain sensation to the spinal cord

A

C fibres

A delta fibres

33
Q

Difference in myelination between C fibres and A delta fibres

A

C fibres are unmyelinated

A delta fibres are myelinated

34
Q

Difference in speed of transmission between C fibres and A delta fibres

A

A delta fibres send pain sensation quicker

35
Q

Specialised receptors in the skin which are able to detect pain

A

Nociceptors

36
Q

Pathway in the spinal cord which carries pain and temperature sensation

A

Lateral spinothalamic tract

37
Q

Pathway in the spinal cord which carries crude touch and pressure sensation

A

Anterior spinothalamic tract

38
Q

Blood vessel involved in a stroke causing thalamic pain syndrome

A

Thalamoperforating branches of the posterior cerebral artery

39
Q

Features of thalamic pain syndrome

A

Contralateral loss of sensation

Contralateral burning and tingling with allodynia

40
Q

Eponymous name for thalamic pain syndrome

A

Dejerine-Roussy syndrome

41
Q

Parts of the brain involved in thirst perception

A

Subfornical organ (sits on the underside of the fornix near the foramina of Monro)
Vascular organ of lamina terminalis (sits near the subfornical organ and the median prominence)
Median preoptic nucleus of the hypothalamus

42
Q

Neurotransmitter which propagates thirst signals

A

Angiotensin II

43
Q

Location of baroreceptors which stimulates thirst when hypotension occurs

A

Aorta

Carotid

44
Q

Organ which produces angiotensinogen

A

Liver

45
Q

Enzyme which modifies angiotensinogen to angiotensin I

A

Renin

46
Q

Organ which produces renin

A

Kidneys

47
Q

Trigger for the kidneys to produce more renin

A

Decreased renal perfusion

48
Q

Enzyme which modifies angiotensin I to angiotensin II

A

ACE

49
Q

Organs which produce ACE

A

Lungs

Kidneys

50
Q

Effects of angiotensin II

A

Propagates thirst signals
Increases sympathetic activity (to increase contractility of heart among other effects)
Increases tubular Na+ and Cl- reabsorption and K+ excretion in the kidneys to increase water retention
Increases aldosterone secretion in the adrenal gland (promotes Na+ and water retention)
Vasoconstricts to increase BP
Causes the pituitary to secrete ADH which leads to increased water reabsorption in the collecting duct

51
Q

Two causes of increased thirst

A

Decreased circulating volume

Increased salt concentration of the interstitial fluid

52
Q

Steps leading to increased thirst

A

Receptors in the subfornical organ and the organum vasculosum of lamina terminalis detect the concentration of blood plasma and the presence of angiotensin II
They activate the median preoptic nucleus
Water seeking and ingestion behaviour is initiated

53
Q

Lesions seen in Kluver-Bucy syndrome

A

Bilateral lesions of the amygdala and hippocampus

54
Q

Features of Kluver-Bucy syndrome

A

Docility and decreased aggression
Hypersexuality
Hyperphagia and hyperorality
Visual agnosia

55
Q

Type of inheritance of Laurence-Moon-Biedl syndrome

A

Autosomal recessive

56
Q

Features of Laurence-Moon-Biedl syndrome

A
Obesity
Intellectual disability
Polydactyly
Diabetes insipidus
Blindness due to retinitis pigmentosa
Spastic paraplegia
57
Q

Chromosome affected in Prader-Willi syndrome

A

15

58
Q

Features of Prader-Willi syndrome

A
Obesity and hyperphagia
Intellectual disability
Hypotonia
Short stature
Diabetes mellitus
59
Q

Usual trigger for Kleine-Levin syndrome

A

Viral infection

60
Q

Feature of an episode of Kleine-Levin syndrome

A

Hypersomnia
Hyperphagia
Hypersexuality

61
Q

Usual course of Kleine-Levin syndrome

A

Symptoms begin in adolescence
Repeated episodes each lasting weeks to months
Months of normal behaviour between episodes
Gradually increasing time between episodes and decrease in severity of episodes
Reduction or resolution in symptoms in 20s

62
Q

Permeability of potassium ions across the cell membrane

A

Relatively permeable

63
Q

Permeability of chloride ions across the cell membrane

A

Freely permeable

64
Q

Permeability of sodium ions across the cell membrane

A

Relatively impermeable

65
Q

Permeability of organic ions across the cell membrane

A

Relatively impermeable

66
Q

Ion which causes presynaptic vesicles to release neurotransmitter into the synaptic cleft

A

Ca2+

67
Q

Ion which sees an increased concentration in the axon terminal prior to depolarisation

A

K+

67
Q

Ion which sees an increased concentration in the axon terminal prior to depolarisation

A

K+