Lecture 19- Neuron Structure+ Function Flashcards
Describe the structure of a neutron and a nerve cell body
Perikaryon (cell body)- with Dendrites Nucleus, Nissl bodies- RER, free ribosomes- protein synthesis
Axon hillock- down the myelinated axon which have nodes of ranvier going to the nerve terminals
What are the different types of neurones?
Motor- CNS to PNS
Sensory- PNS towards CNS: Psuedounipolar neurones, bipolar neurones
Integrative- only in CNS. Collate all info with dendrites
Anaxonic-act as relays
Anterograde vescicles- hoping from the cell body to the distal end (muscles/target tissue)
1) Vesicle+ mitochondria picked up by transport system
2) The microtubule has kinesin attached that attaches to the vesicle
3) The kinesin moves along the microtubule with the vesicle attached
Retrograde vesicle
1) Brings back recycled vesicle via Dynactin attached to the microtubule
2) Recycled by the Golgi apparatus+ broken down into products by the protesosome.
Neurotransmitter synthesis
1) Neurotransmitter synthesised by the cell body and transported down the axon
What happens to the neurotransmitter after it’s released?
1) It is broken down by an enzyme
2) Or re-uptaken to be recycled
What happens to the vesicle after it has undergone exocytosis?
1) Recycled through Clathrin-coated endocytosis
2) Lose to neurolemma
Different types of synapses
1) Axodendritic- directly to the plasma membrane
2) Axodendtric- Axon terminal synapse with a dendritic spine
3) axoaxonic- Synapse at the axon in bouton
What is a peripheral nerve?
Nerves coming from the Dorsal and ventral horn
Peripheral nerve structure
End- Endoneurium- Loose
Peri-Perineurium- loose
Epiphanising- epinuerium- Dense irregular
Paranoia- Paranuerium- Fascia- Adipose- Shock absorber
Myelinated peripheral nerves
Each axon has a myelin sheath around with a Schwann cell imbedded
Non-myelinated peripheral nerves
Schwann cell around a group of axons to hold the bundles together
Slower propagation of Action potential
How does Myelination occur?
1) The Mesaxon membrane initiates myelination by surround the embedded axon
2) The abaxonal domain and adaxonal domain both move simultaneously and the Mesaxon membrane wraps around the axon and creates many layers.
3) Cytoplasm extruded between two opposing plasma membranes of the Schwann cell
Node of ranvier
Core of saltatory conduction along myelinated axons and has an abundance of voltage gated Na+ channels and allows for a faster propagation of action potential
Name the glial cells
Support cells in the CNS Oligodendrocytes Astrocytes Ependymal Microglial cells
What are oligodendrocytes?
Same as Schwann cells but in CNS
Difference: wraps around more than one axon simultaneously
Astrocyte
Star-like structure
- Contribute blood-brain barrier (encapsulate blood vessels)
- Have perineural feet: Maintain chemical concentrations
- Regulate nerve impulses by releasing gamma amino butyric acid
Ependymal cells?
Found:
Satellite cell - PNS
- Attaches to pseudounipolar cell body (perikaryon)
- Only found on sensory neurones cell bodies
- Similar functions to astrocytes
Microglial cells
Resident macrophage
- Immune function
- Ingest pathogens
- remove damaged nerve cells
Ependymal cells
Found- Line the spinal canal, Posterior to ventral median fissure
Structure- Have cilli and microvilli
Function: Synthesise and secrete Cerebrospinal fluid in the ventricles
Cillia: waft the CSF thru ventricle to the spinal chord
Microvilli: absorb CSF for removal of pathogens
Modified tight junctions: control fluid release into brain
What is multiple sclerosis?
- Degenerative
-Autoimmune- degradation of myelin - Loss of conduction velocity
Symptoms:
-Fatigue
-Slurred speech - Muscle spasms
-vision problems
What is grey matter?
- Nerve cell bodies
- Dendrities
- Axon terminals
- Non-myelinated axons
White matter
Has myelin
