3) Neurones and Glia Flashcards
Give examples of types of glia:
Astrocytes
Oligodendrocytes
Microglia
What are the functions of astrocytes?
Provide structural support and nutrition to neurons
Remove neurotransmitters
Maintain ionic environment (K+ buffering)
Help form BBB
How do neurones obtain metabolites for energy production?
Astrocytes store glycogen which they can metabolise to lactate and shuttle to neurones
Glucose directly
Describe the membrane potential of glial cells:
Very negative due to chloride ion permeability
What are the functions of microglia?
Phagocytosis and APC
What is the function of the blood brain barrier?
Limits diffusion of substances from blood to brain ECF, maintaining correct environment for neurones
What are the constituents of the blood brain barrier?
Brain capillaries, basement membrane and end feet of astrocyte processes
Describe how the CNS has immune specialisation:
Doesn’t undergo rapid rejection of allografts
Inhibits initiation of pro-inflammatory T cell response as skull cant tolerate volume expansion
What are the types of neurotransmitters found in the brain?
Amino acids
Biogenic amines and ACh
Peptides
What are some examples of amino acid neurotransmitters in the brain?
Glutamate, GABA and glycine
What are some examples of biogenic amine neurotransmitters in the brain?
Noradrenaline, dopamine, serotonin, histamine
What are some examples of peptide neurotransmitters in the brain?
Dynorphin, enkephalins, substance P, somatostatin, CCK, neuropeptide Y
What are the two types of glutamate receptors?
Ionotropic and metabotropic
Describe ionotropic glutamate receptors:
AMPA, kainate and NMDA - all Na+ and K+ permeable
Cause depolarisation and increased excitability
Describe metabotropic glutamate receptors:
G proteins - linked to changes on IP3 and Ca2+ mobilisation or inhibition of adenylate cyclase and decreased cAMP
Describe how glutamate receptors have a role in learning and memory:
Strong, high frequency stimulation causes long term potentiation - stronger synapses and higher responses
Why can damage after stroke be dangerous to neurones?
Damaged area with depolarised cells which allows Ca2+ to enter cells and at high concentrations this is excitotoxicity
Where do GABA and glycine act in the CNS?
GABA in brain
Glycine in brainstem and spinal cord
How do barbiturates and benzodiazepines act and what are their effects?
Bind to GABAa receptors and enhacne the response to GABA
Anxiolytic and sedative actions
What are some cholinergic pathways in the CNS?
Originate in basal forebrain and nucelus basalis, project to cerebral cortex and hippocampus
Local interneurones in corpus striatum
What are cholinergic neurones involved with?
Arousal, learning, memory and motor control
In what disease is there degeneration of nucleus basalis?
Alzheimer’s
What are some dopaminergic pathways in the CNS?
Nigrostriatal - motor control
Mesocortical and mesolimbic - mood, arousal, reward
What is the cause of Parkinson’s disease?
Loss of dopaminergic neurones in substiantia niagra
What is the cause of schizophrenia?
Excess of dopamine
Why is L-DOPA given in the treatment of Parkinson’s?
What is given alongside?
Can cross the BBB
Give carbidopa that inhibits aromatic AA decarboxyalse
Where do noradrenaline containing neurones originate?
Locus coeruleus
Why do amphetamines cause increased wakefulness?
Increase the release of NA and dopamine
Where do serotonin containing neurones originate?
Raphe nucleus
What are the functions of serotonergic neurones?
Sleep/wakefulness, mood
