Buscar
Estás en modo de exploración. debe iniciar sesión para usar MEMORY

   Inicia sesión para empezar

level: 15.5 Structure and function of synapses

Questions and Answers List

level questions: 15.5 Structure and function of synapses

QuestionAnswer
Synapse meaning- Point where 1 neuron communities with another or with an effector - Important in linking different neurons together therefore coordinating activities - Transmits info, not impulses
Structure of synapse- Transmits info from 1 neuron to another through neurotransmitters - Neurons separated by small gap, synaptic cleft - Neuron that releases neurotrans. called presynaptic neuron - Axon of this neuron ends in swollen portion, synaotic knob - This possesses many mitochondria + large amounts of endoplasmic reticulum - These required in manufacture of neurotrans., takes place at axon - Neurotrans. stored in synaptic vesicles - Once NT released from vesicles, diffuses to postsynaptic neuron, possesses specific receptor proteins on its membrane to receive it
Features of synpases- Unidirectionality - Summation
Unidirectionality- Syanpases can only pass info in 1 direction - From presynaptic neuron to postsynaptic neuron - In this way, act as valves
Summation- Low-frequency AP often lead to release of insufficient concs. of NT to trigger a new AP in postsynaptic neuron - But can do so in process called summation
Two types of summation- Spatial summation - Temporal summation
Spatial summation- 2 impulses from 2 or more different nuerones arrive at the same time will summate to produce a threshold potential
Temporal summation- 2 sub-threshold stimuli arrive from the same presynaptic neurone in a short period of time - These summate to produce a threshold potential
Inhibition- Synapses that prevent production of and AP on postsynaptic neuron - By opening chloride ion protein channels on the postsynaptic neuron - This causes K gated ion channels to open, K ions are able to diffuse out
Drugs can increase transmission of impulses at a synapse by:- Causing more NT to be produced in the synaptic knob - Causing more NT to be released at the presynaptic membrane - Preventing the breakdown of NTs by enzymes
Drugs can decrease transmission of impulses at a synapse by- Preventing production of NT in the presynaptic knob - Preventing the release of NT at the presynaptic membrane - The NT that leaks out of the cell is destroyed by enzymes
MDMA- MDMA inhibits the reuptake of serotonin into the presynaptic neurone by binding to the specific proteins that enable serotonin reuptake, located on the presynaptic membrane; this increases the amount of serotonin present in the brain - Serotonin is usually reabsorbed into the presynaptic neurone to be recycled for future action potentials - MDMA also triggers the release of further serotonin from presynaptic neurones, further adding to the increase