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43 Cards in this Set
- Front
- Back
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Up until the time of _______,
people believed that the mind commanded the body |
Descartes
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Descartes proposed the _____ ____ allowed fluid to flow
through nerves and into muscles, allowing them to fill up and move.... How was this theory proved wrong? |
pineal
body; Descartes was proved wrong when someone put their arm in water and flexed: the water level did not change |
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Stephen Grey proposed it was
_______ that caused the body to move |
electricity;
Example: rub balloon on carpet and place it near head = it attracts your hair |
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When walking through the
market, Galvani noticed that lightening caused frog legs to “jump”. He got some frog legs and stimulated them with electricity which resulted in _____ ______ |
Muscle constricted
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Hitzig and Fritsch stimulated
the cortex of a dog and got muscles to move on the opposite side of the body. Helmholtz took frog leg and measured the distance between stimulation and muscle contraction. This distance was measured to be ______ meters/second. Everyone knew that electricity moves at the speed of light so whatever was that generates muscle movement is NOT electricity |
40.
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JZ Young noticed that squids
propel themselves through the water by contracting their mantel. Suggested to Hodgkins and Huxley to study the giant axon of the squid. They dissected the axon out and took recordings from it Found that the inside of the axon is ______ charged compared to the outside |
negatively
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In reference to the inside of neurons, the charge inside is about ______. This is called the ______ potential.
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70 microvolts; resting
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Ions (positively or negatively charged molecules) that make up the resting
potential diffuse via two means: What are they? |
Down its concentration gradient
- ions will evenly distribute throughout a substance Down its electrostatic gradient -charges will evenly distribute throughout a substance |
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What is an ion?
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positively or negatively charged molecules
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Resting potential has three
features: What are they? |
1. Inside of the cell accumulates
negatively charged proteins 2. Potassium (K+) are free to leave and enter the membrane freely 3. Sodium (Na+) wants to enter the cell due to the electrostatic gradient, but is pumped out via the K/Na pump |
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Graded potentials are voltage
changes in the membrane potential There are of two types: hyperpolarization and depolarization. Which one makes the inside of the membraine more negative and which one makes the inside of the membrane more positive? |
Hyperpolarization: make the
inside of the membrane more negative |
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How do graded potentials
occur? |
-Membrane becomes hyperpolarized via 2
means: 1. when K+ ions leave the cell 2. When Cl- ions enters the cell |
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Membrane depolarizes when
______ ions enter the cell |
Na+
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Toxins are selective for certain
channels 1. TEA blocks _____ channels 2. TTX blocks _____ channels |
K;
Na |
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Describe an action potential
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1. Membrane begins to depolarize
2. When inside of membrane hits -50 mV, the membrane completely depolarizes, passing 0 mV 3. Membrane voltage quickly hyperpolarizes, and becomes more negative then -70 mV 4. Then resting potential of -70 mV is restored |
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How fast does an action potential take to propogate?
How many action potentials could you have in a second? |
This process happens within
1-2 ms So, you could have up to 200 action potentials in one second !! o |
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Threshold of the membrane is
defined by ______ -_____ _____? |
the voltage gated
channels |
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At -50 mV, ____ channels
change shape and open, allowing ____ to rush into the cell |
Na; Na (sodium for both)
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Gated ___ channels are slower
to open, so there is a large influx of Na before K exits |
Potassium (K)
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During ________, there cannot
be another action potential |
absolute refractory
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-During _____ ______, you can generate another action potential, but the
voltage required is larger (more +) |
relative refractory
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To reach the threshold, you
need graded potentials to open Na channels This allows enough ___ in to bring the voltage to -50 mV |
Na (sodium)
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Action potentials give rise to
successive action potentials all the way down the axon = ______ _______ |
nerve impulse
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The impulse only travels in
one direction (down the axon) due to the _______ ______ |
refractory periods
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_____ _______ is the
means which the action potential travels down the axon |
Saltatory conduction
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If you remember, the axon is
covered by glia cells (called _________) |
myelination
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Between each cell on a myelinated axon is a small
gap of axon that is not covered, called what? What function does this gap serve? |
a node of
Ranvier; The action potential “jumps” from node to node all the way down the axon |
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How are cellular inputs dealth
with? |
Via EPSP and IPSP
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Eccles found that a neuron
has both _______ and ______ inputs... Positive ones are ______ ______ ______ _____ whereas Negative ones are _____ ______ ______ _____ |
negative; positive
excitatory post-synaptic potential (EPSP) inhibitory post-synaptic potential (IPSP) |
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Eccles found that a neuron
has both negative and positive inputs Positive ones are excitatory post-synaptic potential (EPSP) Negative ones are inhibitory post-synaptic potential (IPSP).... These inputs need to be summated by the cell body, resulting in what? |
voltage change at
the axon hillock |
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If there are more EPSP than
IPSP, willl an action potential occur? |
YES!!!
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If there are more IPSP than
EPSP, will an action potential occur? |
NO!!!!
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Sodium channels have
several properties |
1. voltage sensor to detect membrane charge
2. Filter that allows only Na through 3. Has a TTX binding site |
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Voltage sensitive channels are
on the ______ ______, preventing action potentials from generating elsewhere on the axon |
axon hillock
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Name 3 examples of Na (Sodium) Channels
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1. Stretch sensitive
2. Chemical sensitive 3. Light sensitive |
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Describe in detail a stretch sensitive sodium (Na) channel
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- Hair has a dendrite wrapped around its root,
and when hair moves in certain direction, the dendrites stretch - Stretch sensitive Na channels then open, and graded potentials result |
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Describe in detail a chemical sensitive Na channel
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between the neuron and muscle, Na channels
have acetylcholine binding sites, that when bound, open and allow Na in and K out so muscle can have an action potential and contract |
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Describe in detail a light sensitive Na channel
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- pigments in the eye look a lot like Na
channels, and when light hits them, they open up and let Na in |
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what are head direction cells?
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-rats have cells in their head that fire when
their head is oriented in a certain direction -(doesn’t matter what room the rat is brought to, they will only fire in that same direction) |
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What is a Halle Berry neuron?
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Single cell recordings of pyramidal cells of
the hippocampus revealed that we have a “Halle Berry” neuron.... formerly called “grandmother cell” |
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What is an EEG?
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Electroencephalogram (EEG) records
electrical activity of the brain through the skull. The signals recorded are graded potentials |
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Epilepsy is a condition where
a person can have a short to long period of “absence”. ______ _____- is abnormal activity in a small part of the brain _______ ______ - abnormal activity in all neurons, leaving the person unconscious for a short time |
Petit mal;
Grand mal |
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What is optogenetics?
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Use of light pulses to activate
brain. For example: When ChR2 is injected in mouse brain, and blue light is shone, you can get whisker movements for each pulse In contrast, if you inject halorhodopsin in mouse brain, yellow light will stop neuron responses. If both are injected into the mouse, blue light will cause them to move and yellow will cause them to stop |
