Lecture 2.2: Neural Components and Networks Flashcards
What are the 2 Types of Cells in the Nervous System?
1) Neuroglia
2) Neurones
What are the Roles of Neuroglia? (3)
- Ensure structure, support, nourishment and
protection - More numerous than neurons (3:1)
- Maintain ionic state, scaffolding, aid recovery/
restructure
What are the Roles of Neurones? (3)
- Functional units of the nervous system (89 billion in
the brain) - React to chemical and sensory stimuli
- Conduction of impulses
- Emit specific chemical regulators
What Neuroglia are found in the CNS? (4)
- Astrocytes
- Oligodendrocytes
- Microglia
- Ependymal Cells
What does the CNS consist of? (2)
- Brain
- Spinal Cord
What is the Role of Astrocytes?
Maintain electrochemical environment for neurones
and help form the BBB
What is the Role of Oligodendrocytes?
Myelinate neurons in the CNS
What is the Role of Microglia?
- Macrophage-like cells
- Scavengers, modulate inflammation, cell turnover and
death
What is the Role of Ependymal Cells?
Control the production and flow of cerebrospinal fluid (CSF), brain metabolism, and waste clearance
What Neuroglia are found in the PNS? (2)
- Schwann Cells
- Satellite Cells
What is the Role of Schwann Cells?
Myelination of Axons
What is the Role of Satellite Cells?
Maintain electrochemical environment for neurones in the PNS, sympathetic and parasympathetic systems
What are Synapses?
Junctions that allow information to be transferred from 1 neurone to another neurone or from a motor neurone to a skeletal muscle fibre
What are the 2 Types of Synapses?
- Chemical (most common)
- Electrical
How do Electrical Synapses work?
- Pre and post-synaptic membranes are linked via gap
junctions - Chemical signals simply diffuse through
- Quicker
- Allows mass coordination of neurones
What are the 2 Broad Categories of Neurotransmitters?
1) Small Molecule Neurotransmitters
2) Neuropeptides
Examples of Small Molecule Neurotransmitters (7)
- Acetylcholine
- GABA
- Dopamine
- Adrenaline
- Noradrenaline
- Serotonin
- Histamine
What are Neuromodulators?
- Subset of neurotransmitters
- Do not act directly on ion channels
- Act diffusely, at a distance
- Slower action: often modulate synaptic transmission,
often via presynaptic GPCRs
Why are Neuromodulators important?
Important molecular targets for CNS-active drugs
Botulinum Toxin MoA
Toxin inhibits the release of acetylcholine at the neuromuscular junction, leads to paralysis
What is Motor Neurone Disease?
- Group of disorders that leads to loss of motor
neurones - Progressive
- Upper / lower or combined motor neuron signs
- Poor prognosis
How is diagnosis of Motor Neurone Disease done?
- Normal nerve conduction studies
- MRI brain may show cortical atrophy
What is the Treatment of Motor Neurone Disease?
Only supportive
What is Multiple Sclerosis?
- 2 or more, separate, episodes of CNS demyelination
- Plaques seen in white matter of brain or spinal cord
- More commonly - per-ventricular/corpus callosum/
optic tracts - Oligoclonal bands in CSF
Symptoms of Multiple Sclerosis (8)
- Fatigue
- Difficulty Walking
- Vision Problems
- Problems controlling the Bladder
- Numbness/Tingling
- Muscle Stiffness & Spasms
- Problems with balance and co-ordination
- Problems with thinking, learning and planning
What are Oligoclonal Bands in CSF? What do they indicate?
- They are proteins called immunoglobulins
- Indicates inflammation of the central nervous system
- Indicate Multiple Sclerosis
Guillain-Barre Syndrome
- Rapid onset muscle weakness due to auto-immune
damage to myelin in the PNS - Peripheral neuropathy
- Predominantly motor
Management of Guillain-Barre Syndrome
- Plasma exchange
- IV immunoglobulin
- 20% of patients may need respiratory support
Symptoms of Guillain-Barre Syndrome (9)
- Difficulty Walking
- Paralysis
- Difficulty Breathing
- Blurred or Double Vision
- Difficulty Speaking
- Problems Swallowing/Chewing
- Difficulty Peeing
- Constipation
- Persistent and/or Severe Pain
What is Myasthenia Gravis?
- Auto-antibodies against acetylcholine receptors:
Autoimmune synaptopathy - Autoimmune destruction of myelin all over
- This prevents nerve impulses from triggering muscle
Symptoms of Myasthenia Gravis (7)
- The more the muscle is used the weaker it becomes
- Drooping Eye Lids
- Avoidance of Activities
- Intermittent Double Vision
- Issues Chewing Foods
- Speech Dysarthria
Treatment of Myasthenia Gravis (3)
- Cholinesterase Inhibitors
- Immunosuppression
- Thymectomy
Neurotransmitters & Disease Linkages: Dopamine
- Parkinson’s Disease
- Schizophrenia
Neurotransmitters & Disease Linkages: Acetylcholine
- Alzheimer’s Disease
Neurotransmitters & Disease Linkages: Dopamine & Noradrenaline
- ADHD
Neurotransmitters & Disease Linkages: GABA
- Alcohol Addiction
- Anxiety
