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level: 6.5 Neurons and Synapses

Questions and Answers List

level questions: 6.5 Neurons and Synapses

QuestionAnswer
draw and label a neuron (4)dendrite = sensory info (chemical) goes and is converted into electrical impulses Soma (cell body) = organelles and nucleus for cell metabolism Axon = some neurons have parts covered in myelin sheath to increase the conduction speed axon terminal = electrical impulse from the axon stimulated the release of chemical messengers into the synapse called neurotransmitters
What are the uninsulated parts of the axon called?nodes of ranvier
what is it called when myelination increases the conduction speed?saltatory conduction
how does myelin sheath help with increasing conduction speed?action potential hops between the nodes instead of spreading continuously along the axon making it faster
What is the myelin sheath made up of?protein and phospholipids made by schwann / glial cells
what color does myelinated neurons appear as? what are the negatives of myelinated neurons? (2)white matter takes up a lot of space
How is resting potential maintained? charge? (3)charge difference is -70mV inside = more negative ATP dependent on Na + K pumps (active translocation) 3 Na+ out 2K+ in
What is the CNS? which neurons are used in it?central nervous system = relay neurons and brain and spinal cord
What is PNS? which neurons are used?sensory and motor
What 3 things happens during action potential? (4)when a neuron is firing the charge changes depolarisation - changes from negative to positive charge repolarisation - restores membrane potential = negative internal refractory period - resting potential restored
describe the process of depolarisation? (4)changes from negative to positive charge Na channel opens and causes a passive influx of Na into the neuron because there is a greater amount of Na outside the neuron causes charge to change to 30+ mV
Describe the process of repolarisation? (3)becomes a more negative charge passive efflux of K out of the neuron because it is more concentrated in the neuron charge becomes -80mV
Describe the process of the refractory period? (2)restores resting potential Na and K pump opens
What are nerve impulses?action potential spreads across axons through depolarisation = causes ion channels open
what is the threshold potential? specific number?min stimulus needed to open voltage gated ion channels (-55mV)
what are oscilloscopes?measures the membrane potential across neuron
what are synapses between?junctions bw neurons and receptor/ effector cells
what is the process of synaptic transfer? which ion is released? (5)1) action potential goes to axon terminal 2) causes voltage gated Ca2+ channels to open 3) Ca2+ signals vesicles to travel to the presynaptic membrane and binds with it 4) NT released via exocytosis and binds with the receptors on the postsynaptic neuron 5) electrical impulse initiated in post by the NT
What happens after the neurotransmitter activates the electrical impulse in the post? (2)neurotransmitter is either recycled by reuptake pumps or degraded by enzymes
What are neurotransmitters?chemical messengers released from neurons due to depolarisation can trigger (excitatory) or prevent (inhibitory) a response
what does acetylcholine trigger in the body? (2)muscle contraction / returns body to routine (parasympathetic)
which 2 receptors does acetylcholine bind to?nicotinic / muscarinic receptors
why does acetylcholine have to be constantly removed?causes overstimulation = paralysis
what is the process of acetylcholine to cause muscle contraction? (5)1) Acetylcholine made with acetyl COA and choline in axon terminal and is stored in a vesicle 2) AcH attaches to cholinergic receptor on post neuron 3) in synapse ACH is broken down by acetylcholine-esterase 4) choline is transported back into axon terminal to make more acetylcholine 5) can be released into synapse by pre or embedded into post
what are neonicotinoid pesticides used for? how does it work? positives and negatives? (4)used to kill insects because it binds more strongly to their AcH receptors causes paralysis irreversibly binds to nicotine receptors and acetylcholine-esterase can't break it down protects crops but reduces bee + bird populations
what are graded potentials?small changes in membrane potential caused by opening of ligand-gated-ion channels
Example of excitatory NT and how it activated the neuron? which channels are opened?noradrenaline = depolarisation = opens ligand gated Na / Ca channels
Example of inhibitory NT and how it activated the neuron? which channels are opened?GABA = Hyperpolarisation = opens ligand gated K/ Cl channels