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Following an Action Potential, Potassium Channels open up driving membrane potential toward equilibrium. These voltage-gated Potassium channels differ from leak-potassium channels in that they are normally __________ during resting potential, but __________ in response to depolarization. (Thus the term "voltage-gated").
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The "Undershoot" Phase following an Action Potential is caused by _____________.
Hyperpolarization
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The tree-like branches of a neuron are called ______________
Dendrites
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The long thin structure of a neuron that carries information TO another cell is called the __________
Axon
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Which animal species have the longest axons?
- Longest axons occur in the largest animals.
- ex giraffes & elephants from spinal cord to feet, ~2 meters
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What is one major advantage of the blood brain barrier & one major disadvantage
- Advantage: Toxins and viruses don't go to the brain
- Disadvantage: Needed medications or nutrients don't get to brain
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Which chemicals cross the blood-brain barrier PASSIVELY?
- Small, un-charged molecules:
- water, oxygen, carbon dioxide, chemicals that dissolve in fats of membrane
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Which chemicals cross the blood-brain barrier via ACTIVE transport?
Glucose, amino acids, purines, choline, some vitamins, (A & D), iron, some hormones
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Heroin exerts faster effects on the brain than morphine. What can we infer about those drugs?
Heroin crosses the blood-brain barrier.
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When a neuron membrane is at rest, the sodium ions more concentrated __________ of the cell. The Potassium ions more concentrated __________ of the cell
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When the neuron membrane is at rest, what tends to drive the potassium ions OUT of the cell? What tends to draw them INTO the cell?
- OUT: Concentration gradient (higher concentration inside, driving them out)
- INTO: Electrical gradient (post-AP after cell is depolarized, opens K+ voltage-gate channels to send cell back to neutral)
- Also, the sodium-potassium pump.
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What is the difference between HYPERPOLARIZATION and DEPOLARIZATION?
- Hyperpolarization: Makes cell more NEGATIVE
- Depolarization: Makes cell more POSITIVE (by decreasing amount of negative charge) (-/-) = (+)
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During the rise of the action potential, do sodium ions move INTO the cell or OUT of it? Why?
- Move INTO it.
- The voltage-dependent sodium gates open, so sodium can move freely. Sodium is attracted to the INSIDE of the cell by both an electrical and a concentration gradient
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As the membrane reaches the peak of the action potential, what brings it down to the original resting potential?
Sodium Channels CLOSE- causing sodium levels to drop. Voltage-gated Potassium Channels OPEN - Potassium ions EXIT the cell, carrying a POSITIVE charge. Enough potassium ions leave to drive membrane BEYOND usual resting level to short hyperpolarization. Eventually, the sodium-potassium pump removes the higher amount of sodium and adds more potassium to bring back to normal resting level.
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What are the "3 Mantras"?
- 1. Biology is NOT determinism
- 2. Brains produce behavior AND behavior changes brains.
- 3. Multiple approaches COMPLETE, not COMPETE
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In most cases, neuron cluster OUTSIDE the CNS is called a ganglion, & cluster INSIDE is called a nucleus. The exception to this is the __________ _____________, which is located IN the CNS.
Basal Ganglion
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Name the 6 stages of Brain Development
- 1. Neurogenesis (making neurons), mitosis (making cells)
- 2. Migration
- 3. Differentiation
- 4. Synaptogenesis (hook up, make synapses)
- 5. Cell Death (and apoptosis = programmed death)
- 6. Rearrangement (constant/permanent)
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When will a dose-response curve look like a NORMAL distribution?
- When EVEN MORE of the drug gives less effect
- ex Quinelorane
- Dopamine agonist-induced yawning in rates
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Spinal Cord arrangement:
One branch on dorsal side: ___________ info COMING INTO spinal cord.
One branch on ventral route: ___________ - nerve controls muscles.
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How many cranial nerves do we have?
12
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List the 3 Main functions of CSF
- 1) cushion or "shock absorber
- 2) vehicle for delivering nutrients to the brain and removing waste
- 3) flow between cranium and spine & compensate for changes in amount of blood within the brain
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Myelin sheaths in the Periphery: ___________
In the CNS: _______________
- schwann cells
- oligodendrocytes
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Receptors inhibit or excite depending on what _______ _____________ are altered.
Ion channels
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Seven Processesin Neurotransmitter Action (and sites that drugs can act on)
- Synthesis
- Storage
- Maintanance
- Release
- Feedback
- Binding
- Inactivation
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In sensitization, the DRC is pushed to the __________
Left
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Which NT is released when a mouse presses a lever and is chooses to do that
over food and sex and other things?
Dopamine (DA)
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The type of genetics that can alter DNA (gene expression) through methylation is called:
Epigenetics
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