(PM3B) CNS Intro Flashcards

1
Q

What is the sympathetic nervous system?

A

Autonomic - involuntary

(1) Mobilises

(2) Fight/ flight

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2
Q

What is the parasympathetic nervous system?

A

Autonomic - involuntary

(1) Conserves

(2) Rest/ digest

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3
Q

What is the coronal (frontal) plane?

A

Ear to ear

Splits front and back of body

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4
Q

What is the horizontal (transverse) plane?

A

Front to back

Splits top and bottom of body

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5
Q

What is the sagittal plane?

A

Left and right

Splits left side of body from right side of body

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6
Q

What is grey matter?

A

Brain tissue

Dense in neuronal cell bodies

Glial cells + neurophil

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7
Q

What is white matter?

A

Areas dense in myelinated axonal tracts

Fewer cell bodies

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8
Q

What is the cerebral cortex?

A

Contains 90% of brain’s total neurons

Responsible for:
(1) Abstract thought
(2) Judgement
(3) Memory
(4) Interpretation
(5) Integration of sensory input

Proportionally larger in humans than other mammals

Evolutionary young area

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9
Q

What are Brodmann areas?

A

Regions of the cerebral cortex

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10
Q

What is the frontal lobe?

A

A cortical lobe of the brain

Responsible for higher, executive function

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11
Q

What are the cortical lobes of the brain?

A

(1) Frontal lobe

(2) Parietal lobe

(3) Occipital lobe

(4) Temporal lobe

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12
Q

What is the parietal lobe?

A

A cortical lobe of the brain

Responsible for integration of sensory information

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13
Q

What is the occipital lobe?

A

A cortical lobe of the brain

Responsible for visual processing

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14
Q

What is the temporal lobe?

A

A cortical lobe of the brain

Responsible for processing sensory information

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15
Q

What is the limbic system?

A

Responsible for application of emotion to cognitive functioning (fear/ love/ rage/ pleasure)

Includes:

(1) Hypothalamus

(2) Amygdala

(3) Hippocampus

(4) Thalamic nuclei

(5) Olfactory region + others

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16
Q

What brain areas/ systems are responsible for determining overall behaviours?

A

Balance of cortical + limbic functions

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17
Q

What is the thalamus?

A

Area in the brain

In the limbic system

Pre-processor + relay for sensory information

Dysfunction can cause perceptual symptoms, e.g. hallucinations

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18
Q

What is the hypothalamus?

A

Area in the brain

In the limbic system

Coordinates nervous system with endocrine system (via pituitary) + sympathetic nervous system

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19
Q

What is the hippocampus?

A

Area in the brain

In the limbic system

Important for learning + memory

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20
Q

What is the amygdala?

A

Area in the brain

In the limbic system

Involved in fear processing + emotional memories

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21
Q

What are the basal ganglia?

A

Interconnected nuclei within the cerebrum

Responsible for coordinating voluntary motor activity between cerebellum + cortex

Maintenance of posture + muscle zone

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22
Q

What are the main components of the basal ganglia?

A

(1) Striatum

(2) Globus pallidus

(3) Subthalamic nuclei

(4) Substantia nigra

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23
Q

What can happen following basal ganglia dysfunction?

A

(1) Huntington’s disease

(2) Parkinson’s disease

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24
Q

What is the excitatory neurotransmitter in the basal ganglia?

A

Glutamate

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25
Q

What is the inhibitory neurotransmitter in the basal ganglia?

A

GABA

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26
Q

What is the modulatory neurotransmitter in the basal ganglia?

A

Dopamine

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27
Q

What is the brainstem?

A

Oldest part of the brain (in evolutionary terms)

Contains visual, auditory + motor centres

Responsible for involuntary motor functions

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28
Q

What are the components of the brainstem?

A

(1) Midbrain

(2) Pons

(3) Medulla

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29
Q

What are the main responsibilities of the brainstem?

A

(1) Respiration

(2) Cardiovascular control

(3) Pain sensitivity control

(4) Alertness

(5) Consciousness

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30
Q

What is the relay station in the brainstem?

A

Reticular formation monitors + influences CNS input + output

(1) Ascending: Carries information TO the brain

(2) Descending: Carries information AWAY from the brain

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31
Q

What does the ascending relay station do in the brainstem?

A

Carries information to the brain

From the periphery

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32
Q

What does the descending relay station do in the brainstem?

A

Carries information to the periphery

From the brain

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33
Q

Where are the majority of cell bodies for amine neurotransmitters contained?

A

Brainstem

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34
Q

What are the main neurotransmitters in the brainstem?

A

(1) Dopamine

(2) Noradrenaline

(3) 5-hydroxytryptamine (serotonin)

(4) Cholinergic neurons

35
Q

What are neurons?

A

Principle signalling units of the NS

36
Q

What are glia?

A

(1) Oligodendrocytes: Make myelin

(2) Astrocytes: Homestasis + synaptic modulation + BBB

(3) Microglia: Brain’s immune system

(4) Ependymal cells

37
Q

What are astrocytes?

A

Type of glia

Stellate (fibrous + protoplasmic)

(1) Physical support for neurons

(2) Neurotransmitter uptake

(3) Ionic homeostasis

(4) Signalling to neurons

38
Q

What are oligodendrocytes?

A

Type of glia

Myelinating cells of CNS

Each cell myelinates several axons

39
Q

What are microglia?

A

Type of glia

Macrophage-like cells

Cells of the immune system in the CNS

Respond to CNS injury + inflammation

Phagocytose foreign bodies

Contribute to repair + injury

40
Q

What is the blood brain barrier?

A

High-selective + partially permeable membrane

Barrier to protect brain from periphery

(1) Endothelial cells form tight junctions

(2) Tight junctions make the brain inaccessible for polar molecules (unless actively transported)

41
Q

What is receptor mediated-transcytosis?

A

Mechanism by which some large molecules enter the CNS

42
Q

What is the role of efflux transporters in the blood brain barrier?

A

Actively pump some molecules out of the brain

43
Q

How do most drugs pass the blood brain barrier?

A

via diffusion

Needs low molecular weight + high lipid solubility

44
Q

What are the key factors which determine if a molecule can diffuse through the blood brain barrier?

A

(1) Must be low molecular weight

(2) Must have high lipid solubility

45
Q

What are the structural features of a neuron?

A

(1) Dendrites
- Basal
- Apical

(2) Cell body

(3) Axon
- Initial segment
- Hillock
- Myelin sheath
- Node of Ranvier

(4) Nerve terminals
- Presynaptic terminal

46
Q

How can neurones differ morphologically?

A

(1) Shape

(2) Spines

(3) Myelinated/ unmyelinated

47
Q

What percentage of neurons use glutamate as a neurotransmitter?

A

50%

48
Q

What percentage of neurons use GABA as a neurotransmitter?

A

30%

49
Q

What are some of the most common neurotransmitters used by neurons?

A

(1) Glutamate

(2) GABA

(3) Acetylcholine

(4) Neuropeptides

(5) Amines (serotonin/ noradrenaline)

50
Q

Which structures within the neuron are responsible for processing?

A

(1) Dendrites

(2) Cell body

51
Q

Which structures within the neuron are responsible for output?

A

(1) Axon

(2) Nerve (axon) terminals

52
Q

What are some of the positive and negative charged ions used for transmission of an electrical signal?

A

(1) Cations:
- Na+
- Ca2+
- K+

(2) Anions:
- Cl-
- Protein anions

53
Q

What is the approximate charge of the inside of a neuronal cell?

A

-70mV

54
Q

In a neuronal cell, which ions are at high concentration extracellularly?

A

(1) Ca2+
(2) Na+
(3) Cl-

55
Q

In a neuronal cell, which ions are at high concentration intracellularly?

A

(1) K+
(2) Protein-

56
Q

What is another term for potential difference?

A

Voltage

57
Q

What is another term for voltage?

A

Potential difference

58
Q

How can ion channels be opened?

A

(1) Ligands – ligand-gated channels

(2) Changes in membrane potential – voltage-gated channels

59
Q

What is the role of sodium (Na+) as an electrochemical transmitter?

A

To make the maximum voltage (Vm) more positive

(1) High concentration outside the cell

(2) Sodium channels are closed at resting membrane potential

(3) Channels open – Na+ enters neuron down concentration gradient

(4) Sodium can be pumped back out of the neuron in exchange for potassium ions (K+)

60
Q

What is the role of potassium (K+) as an electrochemical transmitter?

A

To make the maximum voltage (Vm) more negative

(1) High concentration inside the cell

(2) Many K+ channels are open at rest to fine tune the resting potential (-70mV)

(3) Channels open – K+ moves out of neurons down concentration gradient

(4) K+ is pumped into the cell

61
Q

What is the role of chloride (Cl-) as an electrochemical transmitter?

A

To make the maximum voltage (Vm) more negative

(1) High concentration outside the cell

(2) Most Cl- channels are ligand-gated (GABA + glycine receptors)

(3) Channels open – Cl- flows into neuron down the concentration gradient

(4) Cl- is pumped out of the cell by a co-transporter

62
Q

What is the action potential of a neuron?

A

-70mV at rest – depolarisation drives the action potential towards + beyond 0mV

The binary unit of information transfer in the nervous system

Conveys information intRAcellularly

Initiates electrochemical transmission intERcellularly

Relies on voltage-activated ion channels

63
Q

What are dendrites?

A

Receive signals from other neurons

64
Q

How are post-synaptic potentials graded?

A

Volume of neurotransmitter present

65
Q

What is an excitatory post-synaptic potential?

A

Due to influx of Na+ and Ca2+ ions

Depolarises the cell (makes it less negative)

66
Q

What is an inhibitory post-synaptic potential?

A

Due to influx of negative ions (Cl-)

Hyperpolarises the cell (more negative)

67
Q

What determines whether an action potential fires or not?

A

Overall contribution of excitatory post-synaptic potentials and inhibitory post-synaptic potentials

68
Q

What is temporal summation?

A

When ≥2 post-synaptic potentials coincide

This has a much greater effect than 1 post-synaptic potential

This applies for both inhibitory and excitatory

69
Q

What is spatial summation?

A

Thousands of inputs received by a neuron (excitatory/ inhibitory)

Gives rise to ‘spatial summation’

Determines whether an action potential fires or not

70
Q

Why are some neurotransmitter receptors located presynaptically?

A

Activation decreases further release of neurotransmitter

Called autoreceptors

Self-regulate via negative feedback

71
Q

What is the most common type of autoreceptor?

A

Metabotropic

e.g. 5-HT or dopamine

72
Q

What is an autoreceptor?

A

Activation decreases further release of neurotransmitter

Located presynaptically

Self-regulate via negative feedback

73
Q

What are some examples of neurotransmitter receptors?

A

(1) Glutamate + GABA receptors

(2) a1 + a2 adrenergic receptors (noradrenaline)

(3) 5-HT receptors

(4) D1 + D2 receptors (dopamine)

(5) H1 (histamine)

(6) M1 (acetylcholine)

74
Q

Using glutamate as an example, state the stages of action potential propagation.

A

(1) Resting neuron membrane potential at -70mV

(2) Glutamate released from presynapse

(3) Activates AMPA/kainate receptors, influx of Na+ leading to depolarisation

(4) Cell depolarises (NMDARs slower and voltage-dependent)

(5) Resulting depolarisation called an excitatory postsynaptic potential (EPSP)

(6) Subsequent APs can occur before Vm returns to rest and summate

(7) If/when summated EPSPs reach the threshold for voltage-gated Na+ channel activation (~-55mV), allowing rapid entry Na+ and an action potential will fire, propagating the signal

(8) All or nothing mechanism of action (no partial action potentials)

75
Q

Where are presynapses located?

A

Axon terminals

76
Q

What are the types of postsynaptic cell receptor?

A

(1) Ionotropic – fast-acting channels/ pores

(2) Metabotropic – slower-acting via secondary messengers

77
Q

What is glutamate?

A

(1) Most common excitatory neurotransmitter in the CNS (~50% of neurons)

(2) Acts on ionotropic + metabotropic receptors

78
Q

What is GABA?

A

(1) y-amino-butyric acid

(2) Principal inhibitory neurotransmitter

(3) GABA(a) acts at ionotropic receptors

(4) GABA(b) acts at metabotropic receptors

79
Q

How does an ionotropic receptor work?

A

(1) Ionotropic receptor activation opens channel to allow influx specific ions

(2) Glutamate receptors allow Ca2+ and Na+ ions, GABA(a) allow in Cl- ions

(3) Leads to depolarisation (e.g. glutamate) or hyperpolarisation (GABA)

80
Q

How do metabotropic receptors work?

A

(1) Metabotropic neurotransmitter receptors are G-protein coupled (GPCRs)

(2) On binding ligand, get dissociation and activation of G-protein signalling

(3) Downstream effect depends on which G-protein type has been coupled

(4) Slower, receptor activates intracellular signals, may activate or close ion channels, may increase/decrease gene expression

81
Q

What are some examples of small neurotransmitters?

A

(1) Amino acids (e.g. glutamate, GABA, glycine), typically fast-acting

(2) Monoamines (e.g. dopamine, noradrenaline, serotonin), diffuse effects, neurons of brainstem

(3) Soluble gases (Nitric oxide)

(4) Acetylcholine

82
Q

What are some examples of large neurotransmitters?

A

Neuropeptides (e.g. endorphins, substance P, neuropeptide Y)

83
Q

What are the types of glutamate receptors?

A

(1) Ionotropic: AMPAR (fast activation), NMDAR (slower, voltage-dependent block at resting), Kainate R

(2) Metabotropic: mGluR1-8 (Class I: mGluR1 & 5, Gq; Class II: mGluR2&3, Gi/G0; Class III mGluR4-8, Gi/G0)