ANATOMY - Nervous System Cellular Anatomy Flashcards
What are the three main cell types found in the nervous system?
Neurones
Neuroglia
Ependymal
What are the three types of neuroglial cells?
Oligodendrocytes
Astrocytes
Microglia
What are the three structural classifications of neurones?
Multipolar
Bipolar
Unipolar
What is the main neurone structure involved in transmitting motor information?
Multipolar
What is the main neurone structure involved in olfaction?
Bipolar
What is the main neurone structure involved in transmitting sensory information?
Unipolar
What is a simple neurone communication circuit?
An individual presynaptic neurone stimulates another individual postsynaptic neurone
What is a divergent neurone communication circuit?
One neurone stimulates several neurones
What is a convergent neurone communication circuit?
Several neurones stimulates one neurone
What is a reverberating neurone communication circuit?
Neurone stimulation acts as a continuous feedback loop
Describe the process of neurone communication using neurotransmitters
- Action potential reaches the pre-synaptic axon terminal and triggers an influx of Ca2+ through opening voltage-gated Ca+ channels
- Ca2+ induced changes stimulate the synaptic vesicles to fuse with the pre-synaptic membrane and release neurotransmitters into the synaptic cleft
- Neurotransmitter bind to specific receptors on the post-synaptic membrane, triggering either an EPSP or IPSP
- Eventually the post-synaptic membrane will reach threshold and trigger an action potential
What is an excitatory post-synaptic potential (EPSP)?
Depolarisation of the post-synaptic cell, bringing the membrane potential closer to threshold and triggering an action potential
What is an inhibitory post-synaptic potential (EPSP)?
Hyperpolarisation of the post-synaptic cell, bringing the membrane potential further from threshold and thus further from triggering an action potential
What is the function of the myelin sheath?
The myelin sheath acts as an ‘insulator’ for some axons to minimise the dissipation of the electrical signal that is travelling along the axon, speeding up action potential transmission
What are the Nodes of Ranvier?
The periodic gaps between the myelin sheath where action potentials are triggered along a myelinated axon
What are the two classifications of neurotransmitter receptors?
Ionotropic
Metabotropic
What are ionotropic receptors?
Ligand gated ion channels
What are metabotropic receptors?
G-protein coupled receptors
What are the three ways neurotransmitters can be removed from the synaptic cleft?
Diffusion
Enzymatic breakdown
Reabsorption
Why is it functionally important that neurotransmitters can be removed from the synaptic cleft?
To prevent constant stimulation of the post-synaptic cell and excessive firing of action potentials