Neurons and all that 09.02.2023 Flashcards
What are neurons specialised for?
Electrical signalling
What is the structure of a neuron?
Dendrite and axon
- inputs are via the dendrites
- Action potentials spread along the axon from the axon hillock
What histological stains can be used to stain a neuron?
- H+E: Stains nucleic acids blie
- Eosin: Stains proteins red
How do neurons communicate?
- Vis synapses
- Chemical: neurotransmitters
- Electrical: Direct flow of ions (E.g. brainstem and hypothalamus)
Describe briefly how a chemical synaptic transmission occurs
- Axon potential depolarises synaptic terminal membrane
- Opening of voltage-gated calcium channels leads to calcium influx
- Calcium influx triggers neurotransmitter release
What is neural plasticity?
- Lots of changes in neural/synaptic structure and function in response to neural activity
- This is the basis of learning, memory and adapting
What is neuronal heterogeneity?
Neurons differ in their:
- Size
- Morphology (information processing)
- Neurotransmitter content
- Electrical properties
What is an oligodendrocyte?
- These are the myelinating cells of the CNS
- They can myelinate 50 axons from one cell
What does myelin do?
- Insulates axon segments which enables rapid nerve conduction
- Provides metabolic support for axons
What is a node of ranvier?
- Periodic gaps along myelinated axon
- High density of ion channels
- Action potentials happen here
What is the myelin sheath made up of?
Lipid rich:
- 70% lipid, 30% protein
How is the myelin sheath formed?
- Formed by wrapping of axons by oligodendrocyte processes / Schwann cells
What is a Schwann Cell?
Myelinating cells of PNS
- A single cell myelinates 1.5mm long segments
When does myelination begin?
During 3rd trimester and progresses rapidly during infancy and continues through adolescence
What are microglia?
- Immune cells of the CNS
- Originate from yolk sac
- They are phagocytic and proliferate at sites of injury
