Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Clinical neuroscience > Cellular Physiology of the brain > Flashcards

Cellular Physiology of the brain Flashcards

(58 cards)

Start Studying
1
Q

What are the major cellular components of the nervous system?

A
  • Neurones
  • Glia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the major types of glia found in the CNS?

A
  • Astrocytes (most abundant)
  • Oligodendrocytes
  • Microglia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the functions of astrocytes?

A
  • Structural support
  • Help to provide nutrition for neurones
  • Remove neurotransmitters
  • Maintain ionic environment
  • Help to form blood brain barrier
  • Can react to CNS trauma, helping to form scar tissue and to repair damage
  • Take part in synaptic function
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How do astrocytes help provide energy for neurones?

A
  • Neurones do not store or produce glycogen
  • Rely on glucose from blood
  • When glucose delivery to neurone via blood is low, astrocytes can support neurones for a short while
  • Via glucose-lactate shuttle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Outline how the glucose-lactate shuttle works

A
  • Astrocytes produce lactate
  • Lactate shuttled across to neurones via MCT1/MCT2 transporters
  • Lactate is converted to pyruvate in neurones
  • Pyruvate used to release ATP
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How do astrocytes help to remove neurotransmitters?

A
  • Have transporters for transmitters such as glutamate
  • Astrocyte processes lie very close to synaptic terminals to keep glutamate concentrations low
  • Keeps extracellular concentrations low
  • Allows termination of synaptic response
  • Cell doesn’t remain in permanently depolarised state
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How do astrocytes help to buffer K+ in brain ECF?

A
  • When neurones are very active they fire lots of APs
  • K+ moves out into extracellular space
  • If cells are very active [K+] can get very high
  • Increased [K+] depolarises neurones and causes a positive feedback effect
  • Results in lots of unwanted activity
  • Astrocytes have a very negative cell membrane potential very close to K+ equilibrium potential
  • Ion channels and transporters allow K+ to move into astrocytes e.g. Na+/K+ ATPase
  • Astrocytes are coupled to one another and ions move between them
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the function of oligodendrocytes?

A
  • Responsible for myelinating axons in CNS
  • Schwann cells are responsible for myelinating PNS
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the function of microglia?

A
  • Immunocompetent cells
  • Have long dendrites
  • When microglia recognise foreign material, they become activated
  • Dendrites swell and cells become phagocytic
  • Remove debris and foreign material
  • Brain’s main defence system
  • Can also act as antigen presenting cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What forms the blood brain barrier?

A
  • Endothelial cells of capillaries
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does the blood brain barrier do?

A
  • Limits diffusion of substances from blood to brain extracellular fluid
  • Maintains correct environment for neurones
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the structure of brain capillaries

A
  • Tight junctions between endothelial cells - prevents molecules from freely diffusing across capillaries
  • Basement membrane surrounding capillary
  • End feet of astrocyte processes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What pathways exist across the blood brain barrier?

A
  • H2O, CO2 and O2 can freely diffuse across the BBB
  • Substances such as glucose, amino acids, potassium are transported across
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why do we need to control ion concentration across the blood brain barrier?

A
  • Exercise can increase K+ levels in blood
  • Don’t want K+ to cross BBB
  • Otherwise it will cause unwanted neuronal activity
  • Also need to limit amino acids from crossing BBB as these can act as neurotransmitters
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why is the CNS immune privileged?

A
  • Rigid skull will not tolerate volume expansion
  • Too much inflammatory response would be harmful
  • Microglia can act as antigen presenting cells
  • T cells can enter CNS
  • CNS inhibits initiation of pro-inflammatory T cell response
  • CNS is immune specialised, not isolated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the four main sections of a typical neurone?

A
  • Cell soma
  • Dendrites
  • Axon
  • Terminals
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Outline what happens after neurotransmitter is released

A
  • Depolarisation in terminal
  • Voltage-gated Ca2+ channels open
  • Ca2+ enter terminal
  • Vesicles fuse and release transmitter
  • Neurotransmitter diffuses across synaptic cleft
  • Binds to receptors on post-synaptic membrane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Outline the post-synaptic response

A
  • Depends on nature of transmitter and nature of receptor (ligand-gated or GPCR)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the three classes of neurotransmitters?

A
  • Amino acids
  • Biogenic amines
  • Peptides
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are some examples of amino acid neurotransmitters?

A
  • Glutamate - excitatory
  • GABA - inhibitory
  • Glycine - inhibitory
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the two basic classes of glutamate receptors?

A
  • Ionotropic
  • Metaboptropic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the different types of ionotropic receptors?

A
  • AMPA receptors (Na+/K+)
  • Kainate receptors (Na+/K+)
  • NMDA receptors (Na+/K+ and Ca2+)
  • Ion channel permeable to Na+ and K+ (and in some cases Ca2+ ions)
  • Activation causes depolarisation - increased excitability
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the metabotropic receptor for glutamate like?

A
  • G protein coupled receptor
  • Linked to either: changes in IP3 and Ca2+ mobilisation
  • Or inhibition of adenylate cyclase and decreased cAMP levels
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Outline fast excitatory responses

Study These Flashcards
A
  • Excitatory neurotransmitters
  • Allows cations to influx into cells
  • Causes depolarisation in postsynaptic terminal
  • This is an excitatory postsynaptic potential (EPSP)
  • Depolarisation causes more action potentials
23
What happens if an EPSP exceeds the threshold potential?
- Action potentials are triggered - Large amounts of transmitter in synapse cause increased magnitude of of EPSP and increased frequency of APs
24
What are glutamatergic synapses like?
- Very important, particularly in learning and memory - AMPA and NMDA receptors work together
25
How do glutamatergic synapses work?
- Glutamatergic synapses have both AMPA and NMDA receptors - AMPA receptors mediate initial fast depolarisation - Glutamate activates these receptors - This allows removal of Mg2+ ion from pore of NMDA receptor - Makes them permeable to Ca2+ - Glycine acts as a co-agonist
26
What is long term potentiation?
- If synapse is strongly activated, lots of glutamate is released and additional AMPA receptors are inserted into postsynaptic membrane - Ca2+ entry through NMDA receptors important for induction of LTP - Extra AMPA means that synapse will transmit more readily - Molecular basis for learning and memory
27
What happens if too much Ca2+ enters through NMDA receptors?
- Causes excitotoxicity - Also, if all synapses were to strengthen, they would rapidly reach saturation and information could not be stored
28
How do we prevent too much Ca2+ enters through NMDA receptors?
- Long-term depression - Actively downregulates strength of glutamatergic synapses - May contribute to forgetting
29
What are the inhibitory amino acid neurotransmitters?
- GABA is main inhibitory transmitter in brain - Glycine acts mostly in brainstem and spinal cord
30
What are the GABA receptors?
- Ionotropic - GABAA - Metabotropic - GABAB (GPCR with modulatory roles)
31
How do the GABAA receptors work?
- Permeable to Cl- (have integral Cl- channels) - Opening Cl- channels leads to influx into cell - Hyperpolarisation - Causes inhibitory postsynaptic potential - Leads to decreased action potential firing
32
Which drugs bind to GABAA receptors?
- Barbiturates - Benzodiazepines - Enhance response to GABA
33
What are the uses of barbiturates?
- Rarely used nowadays - Risk of fatal overdose, dependence and tolerance - Sometimes used as anti-epileptic drugs
34
What are the uses of benzodiazepines?
- Used as sedatives and anxiolytics - Addictive - Treat anxiety, insomnia, epilepsy
35
Outline what glycine is like as a neurotransmitter
- Inhibitory - Less widespread than GABA - Released in spinal cord during REM sleep, causing paralysis - Receptors are same as GABA receptors
36
What is the role of other neurotransmitters in the CNS?
- Have a more modulatory role - Involved in discrete pathways
37
Give examples of biogenic amines and acetylcholine
- Acetylcholine - Dopamine - Noradrenaline - Serotonin - Mostly act as neuromodulators - Confined to specific pathways
38
Where is ACh found in the CNS?
- Neuromuscular junction - Ganglion synapse in ANS - Postganglionic parasympathetic - Also a central neurotransmitter
39
What is the role of ACh in the CNS?
- Central neurotransmitter - Acts at both nicotinic and muscarinic receptors in brain - Mainly excitatory - Receptors often present on presynaptic terminals to enhance release of other transmitters
40
Outline the key pathways involving ACh in the CNS
- Arousal - anticholinergic drugs may cause drowsiness - Learning and memory - cholinesterase inhibitors treat Alzheimer's - Motor control - cholinergic drugs treat Parkinson's
41
Outline the cholinergic pathways in the CNS
- Discrete groups of neurones originate in basal forebrain and brainstem (nucleus basalis) - Give diffuse projections to many parts of cortex and hippocampus - Also local cholinergic interneurons e.g. in corpus striatum, thalamus, substantia nigra
42
What is associated with Alzheimer's disease?
- Degeneration of cholinergic neurones in nucleus basalis - Cholinesterase inhibitors are used to alleviate symptoms of Alzheimer's
43
Which key pathways involve dopamine (DA)?
- Nigrostriatal - Neocortical - Mesolimbic
44
Outline the nigrostriatal pathway
- DA - From substantia nigra to striatum - Important for motor control - Degeneration of this pathway causes Parkinson's
45
Outline the neocortical pathway
- DA - From midbrain to cerebral cortex - Mood, arousal and reward
46
Outline the mesolimbic pathway
- DA - From midbrain to limbic system - Mood, arousal and reward - Overactivity in this pathway may contribute to schizophrenia - Amphetamines release dopamine and noradrenaline - produce schizophrenic like behaviour
47
How can Parkinson's disease be treated?
- Levodopa - converted to dopamine by aromatic amino acid decarboxylase (AADC)
48
How do antipsychotic drugs work on?
- As antagonists at dopamine D2 receptors
49
How does levodopa interact with the BBB?
- L-DOPA is converted to dopamine by AADC in brain - L-DOPA crosses BBB readily via Large Neutral Amino Acid transporter (LNAA) - L-DOPA can also be converted in periphery by AADC - High levels of dopamine cause side effects affecting heart, GI tract and urinary system - Carbidopa is co-administered - Inhibits peripheral AADC - Does not cross BBB so production of dopamine from L-DOPA is not affected
50
How does noradrenaline (NA) operate?
- Released by sympathetic postganglionic terminals - Operates through GPCRs (adrenoceptors) - similar both in brain and periphery
51
Which key pathways involve noradrenaline?
- Cell bodies are found in brainstem - Project to widespread areas including cortex, limbic system and cerebellum - Involved in behavioural arousal
52
Where does most NA in the brain come from?
- Locus coeruleus - Locus coeruleus neurones inactive during sleep - Activity increases during behavioural arousal - Amphetamines increase release of NA and increase wakefulness - Low levels of NA are associated with depression
53
Outline the serotonergic pathways in the CNS
- Serotonin, 5-HT - Similar distribution to NA neurones - originates from raphe nuclei of brainstem - Involved in sleep and wakefulness and regulation of mood - Low levels of serotonin cause depression
54
What do SSRIs do?
- Selective serotonin reuptake inhibitors increase levels of serotonin in brain - Can help with depression and anxiety disorders
55
What is the role of histamine in the CNS?
- Has a role in sleep and wakefulness - Stimulates cortex, maintains wakefulness - Some antihistamines can cause drowsiness by antagonising this action
56
Outline the role of peptides in the CNS
- Diffuse slowly - Sometimes widespread - Often alongside other transmitters, modulatory action - Dynorphin and encephalins involved in pain transmission

Clinical neuroscience (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions