| 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 |
