Biology Chapter 6: The Nervous System Flashcards
Mesolimbic pathway
The mesolimbic pathway is the brain’s reward center and is stimulated by things like drug use, engaging in a pleasurable pastime like gambling, or falling in love, rather than mundane non-rewarding tasks. The mesolimbic pathway is a dopaminergic pathway in the brain.
Released into the synaptic cleft of neurons
Acetylcholine
Can antibodies cross the BBB?
NO. In general, antibodies are too large to cross the BBB, are not necessary for brain function, and are well beyond the size of something that could be feasibly transported via protein channels.
Can amino acids cross the BBB?
YES. Anything that crosses the BBB should be essential to brain function and small enough to be transported via a protein channel. Amino acids are necessary for the production of proteins, which are essential for the function of any cell.
Blood brain barrier protects against what kind of agents?
harmful agents that are large or polar
The BBB allows for what kind of molecules to pass?
small lipid-soluble compounds (so small, non-polar compounds) can pass
what happens when you acetylate morphine and how does that impact the permeability to the BBB
Acetylation (replacing the H on the OH group to a -COCH3 on morphine) makes the compound less polar, meaning it can more easily cross the BBB. Acetylation of morphine turns it to heroine
Nervous System arises from what germ layer?
Ectoderm
Sodium potassium pumps what in and out?
3 Na+ OUT
2K+ IN
This makes the inside of the cell slightly negative
Importance of sodium potassium pumps
1) create a negative resting membrane
2) Establish the concentration gradient
What are leaky K+ channels?
channels that allow for potassium to move down it’s concentration gradient (primarily from inside the cell to outside the cell)
contributes to the negative resting potential
Neurons are more permeable to
potassium. way less permeable to sodium
What are leaky sodium channels?
channels that allow Na+ to move into the cell (down its concentration gradient).
DOESN’T make the cell super positive because the cell is WAYYYYYYY more permeable to potassium than sodium
Graded Potential
Think of a rock dropped in a lake - the highest energy is in the middle and dissipates
doesn’t cause an action potential
Glutamate is an
excitatory neurotransmitter
GABA is an
Inhibitory neurotransmitter
EPSP
type of graded potential that occurs in the postsynaptic neuron when it receives an excitatory signal from a presynaptic neuron. It causes a temporary depolarization of the postsynaptic membrane, bringing the neuron closer to its threshold for triggering an action potential.
MAKES THE NEURON MORE POSITIVE
IE glutemate binds to receptor and let’s Na+ into cell
IPSP
is a type of graded potential that occurs in the postsynaptic neuron when it receives an inhibitory signal from a presynaptic neuron. It causes a temporary hyperpolarization of the postsynaptic membrane, making the neuron less likely to fire an action potential.
MAKES THE NEURON MORE NEGATIVE
IE GABA - let’s in Cl- or let’s out K+ (which leaves behind a negative anion from phosphate or protein etc)
An action potential occurs when
EPSP wins over IPSP
Temporal Summation
many excitatory potentials from one neuron triggers threshold point
Spatial Summation
Excitatory potentials from many neurons trigger threshold point
How do you get from -70mV to -55mV (threshold potential)?
By enough EPSPs
Graded potentials occur what part of the cell?
Postsynaptic neuron (receives a signal from a pre-synaptic neuron) in the soma and dendrites
When the voltage reaches -55mV, what happens first?
Voltage gated sodium channels OPEN (activation gate OPENS), letting sodium flow down its concentration gradient into the cell
What is the peak voltage after sodium rushes into the cell during an action potential and why?
+30mV. At this voltage it triggers the inactivation gate to CLOSE. No more sodium rushes in
What happens to voltage gated calcium channels when +30mV is hit?
Calcium rushes into the cell, signals for vesicles containing neurotransmitters to fuse with the terminal and release into the cleft
Depolarize means make more negative or positive?
MORE POSITIVE
Repolarization means making more negative or positive?
MORE NEGATIVE
What happens when to voltage gated potassium cells when 30mV is hit?
Potassium channels open, potassium leaves the cell (follows concentration gradient)
What happens to voltage gated calcium channels once (-90mV) hyperpolarization is hit?
INHIBIT, and therefore calcium doesn’t come into the cell.
neurotransmitters stop being released
What happens @ -55mV?
1) Na+ channels OPEN (Na enters neuron
What happens @ +30mV?
1) Ca+ channels OPEN (Ca2+ enters cell)
2) Na+ channels CLOSE
3) K+ channels OPEN (K+ leaves the neuron)
What happens @ - 90mV?
1) Ca2+ channels CLOSE
2) K+ channels CLOSE
Membrane potential is restored by leaky K+ and leaky Na+ and Na/K pump
Absolute refractory period
Period where you can’t activate another action potential
Relative refractory period
During hyperpolarization where it’s harder to generate an action potential but not impossible
Why is K+ associated with negative charge?
K+ interacts with negative ions like phosphate, protein but leaves negative charge when it leaves the neuron
Does the Na/K pump use ATP?
Yes
The BBB is made of what kind of cells?
Endothelial cells
Cholinesterase
is an enzyme that breaks down acetylcholine (ACh), a neurotransmitter involved in nerve signal transmission. It plays a crucial role in the nervous system by ensuring that ACh does not accumulate excessively, which could lead to continuous nerve stimulation.
Where do you find sphingomyelin
the insulator in the myelin sheath of axons and also a cell signaling agent, but not a storage lipid.
