Synapses and Neurotransmitters Flashcards
(23 cards)
What cells does the human brain contain?
Neurons and glia
What are the roles of glia in the human brain?
- Physical support
- Metabolic support
- Electrical insulation
- Guiding connections
- Signalling
What is the central nervous system made of?
- Brain
- Spinal cord
What is the peripheral nervous system?
- Sensory nervous system
- Motor system
- Autonomic nervous system
What are the divisions of the autonomic nervous system?
Sympathetic and Parasympathetic
What is the sympathetic nervous system?
- Increasing heart rate and blood pressure
- Decreasing digestion
- Fight or flight
What is the parasympathetic nervous system?
- Increasing digestion
- Decreasing heart rate and blood pressure
- Rest and digest
What is controlled by the autonomic nervous system?
- Enteric (GI tract)
- Involuntary movement
- Smooth muscles
- Glands of organs
What does the axon do?
Impulse conduction
What do the dendrites do?
Input from other neurons
What does the axon hillock do?
Action potential generation
What happens at the axon terminal?
Release of neurotransmitter
How are neurones classified based on number of major processes?
- Uni-
- Single axonal process
- Invertebrate neuron
- Bi-
- Two axonal processes
- E.g. retinal bipolar cells
- Multi-polar-
- Multiple axonal processes
- E.g. spinal motor neuron, purkinje cell of cerebellum, pyramidal cell of hippocampus
- Pseudo-uni-
- Single axonal process
- E.g. Dorsal root ganglia cell
How are neurones classified based on dendrites?
- Shape of tree (e.g. stellate, pyramidal)
- Presence/absence of spines
How are neurones classified based on connections?
- Motor
- Internerons
How are neurones classified based on axon length?
- Projection
- Local circuit
How can neurons be classified?
major processes, dendrites, connections, axon length and neurotransmitter
What are synapses?
Points of communication
What is the electrical synapse (gap junction)?
- Fastest and most primitive
- Bi-directional transfer of information
- Physical connection between adjacent cells
- Connexons allow ion movement between cells
- Synchronous activity between neurons
- Rare in neurons in the CNS
- important in development
- Glia-neuron, Glia-glia communication , Cardiac myocytes
What is the chemical synapse?
- Uni-directional transfer
- Pre-synaptic to post-synaptic
- No physical connection
Processes of neurotransmission?
- Neurotransmitter in a vesicle in the presynaptic
- Action potential causes depolarisation opening the calcium ion channel (voltage dependent)
- Calcium ion influx
- Exocytosis
- Fusion of vesicle with membrane
- Interior of vesicle exposed to membrane
- Simple diffusion allows neurotransmitter to move out of the vesicle and into the extracellular space along a concentration gradient
- Diffusion across the synapse
- Binds to receptors on the post synaptic membrane
- Rapid termination of signal
- by re-uptake of neurotransmitter (recycling can be re packaged)
- or Enzyme breakdown of neurotransmitter
What are neurotransmitters? Give examples
- Chemical messengers at the synapse
- E.g. Acetylcholine, noradrenaline (monoamine), dopamine (monoamine), glutamate (major excitatory amino acid), GABA (major inhibitory amino acid)
What are neurotransmitter receptors?
- Recognition site for a neurotransmitter
- Initiates the intracellular signal
- Membrane spanning protein molecules
- transmitter binding causes a structural change
- receptors are specific for a neurotransmitter
- one neurotransmitter - several receptor subtypes
- Nomenclature can be based on most potent, selective agonist
