bio111 lab quiz 2

dendrites

branching, receive signals from other neurons

axon hillock

where the cell body (soma) meets the axon, generates action potential

glia

make myelin sheath

nodes of ranvier

gaps in the myelin sheath where action potential is regenerated down the axon. allows for transmission over long distances

end of axon

has axon terminal with synaptic vesicles, which release NT into synaptic cleft

can ions freely diffuse across cell membrane normally?

no

normal concentration gradient

more Na outside than inside, so would flow inside if given the chance via channels or transporters. opposite for K (higher concentration inside, lower concentration outside)

normal electrical gradient

negatively charged proteins inside and positively charged ions outside

resting potential of neurons

-70mV (more negative inside than outside)

what happens when a neuron is depolarized to the threshold potential

voltage gated sodium channels open at -55mV and sodium goes inside, down gradient (because Na concentrations are usually more concentrated outside than in). depolarizes to +40mV, when the sodium channels close. voltage gated potassium channels open so K can go out (down concentration gradient), reducing membrane potential

refractory period

membrane becomes hyperpolarized and chances of action potential are far lower

main type of channel open when neuron is at rest

K channels

sodium potassium pump

uses energy to move Na out and K in to create concentration gradient

when AP reaches presynaptic terminal

voltage-gated Ca channels open and Ca goes into the cell, which triggers vesicles to fuse to the membrane

interquartile range (IQR)

Q3-Q1. measures spread between middle 50% of data, helps identify outliers

5-number summary

minimum, Q1, Q2/median, Q3, maximum

boxplot

represents 5-number summary. median is at the center of each box in a normal distribution, but moves to the side in a skewed distribution

outlier

values above/below 1.5 x IQR

modified box plots

include outliers outside of whiskers, makes it easier to see outliers

Mann-Whitney U test

tests whether there is a difference between two independent samples. t-test tests whether there is a mean difference, but Mann-Whitney U test tests whether there is a rank sum difference. the advantage of this is that the data doesn’t need to be normally distributed

octanol assay

ASH neuron, which indirectly controls reverse locomotion, senses octonol. When there is food, serotonin is higher, so the neuron can be more activated and therefore cause more reverse locomotion.