(4) Neurotransmitters, synapses, neuronal communication and hormones Flashcards
What is a neuron?
Information processing device, transfers information
What type of signals flow via a neuron (within)
Information flows within a neuron via electrical signals, through action potential
How does information flow between neurons?
Information flows between neurons via chemical signals
Where do neurons communicate?
Synapses
What is a synapse?
The gap between neurons where signals are passed from one to another, from pre to post synaptic neuron
What are the two types of synapses?
-Electrical and chemical synapses
How big is the gap between neurons? (electrical)
Very small gap between two neurones (2-4 nm)
What type of channels do facing membranes have? (electrical)
The facing membranes have large channels that allow ions to move directly from one cell to the other
What is transmission similar to? (electrical)
Transmission from one neuron to the next is similar to action potential conduction along the axon
How fast is transmission at electrical synapses?
Very fast – no time delay
What is Near-Instantaneous Transmission ?
Giving a current injection into the pre synapse to see how fast the post synapse responds, Artificial action potential
What did Eric Kandel do?
Eric Kandel: experiments with Aplysia (sea slug) which led to the understanding of short and long term memory
What is a chemical synapse?
The gap between the axon of one neurone and the dendrite of the next one
How big is the gap between neurons in chemical synapses?
Small gap but much larger than gap junctions (20-40 nm)
How many synapses does a neuron have? (chemical)
Each neurone has many (typically ca 1000) synapses
What are neurons separated by? (chemical)
Neurons are separated by small gap –the synaptic cleft
Are chemical synapses slower or faster than electrical?
slower
What are receptors?
Receptors are membrane proteins that bind neurotransmitters
(post synaptic receptors) Receptors can only bind to specific ________________?
Each receptor type can bind only a specific neurotransmitter – lock-and-key principle: when a transmitter molecule binds to the receptor, the receptor changes shape, causing an ion channel to open
What are ionotropic receptors?
These control the ion channel directly, when bound to the transmitter the ion channel opens and ions flow across the membrane,
What are ionotropic receptors also known as?
also known as ligand-gated ion channels (FAST)
What are Metabotropic receptors?
These also bind with the neurotransmitter but do not open the ion channel, they activate G-Proteins that subsequently control the ion channel (SLOW), needs another messenger to open the channel
What happens if net charge in EPSP and IPSP is below threshold when it reaches the axon hillock?
If net charge (sum of EPSPs+IPSPs) is below threshold (
What happens if net charge in EPSP and IPSP is at threshold when it reaches the axon hillock?
If net charge (sum of EPSPs+IPSPs) is at threshold (-40 mV):AP is elicited
