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28 Cards in this Set

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  • Back
What does the Na+/K+ pump do?
It sets up a concentration gradient ONLY. With more Na outside the cell and more K inside. As K moves down it's gradient (and + ions leave the cell), THAT generates the negative membrane potential.
When is an ion in equilibrium in a cell?
When the cell membrane potential (the electric force) = the ion equilibrium potential (the diffusion force) "the Nernst potential"
Describe the time dependence of Na channel conformational changes
Membrane depolarization makes Na channels open faster. However, after being open the channels inactivate and go through a period of nonconduction

K channels open slower
Define the nerve action potential refractory periods
Absolute-no Action potentials can occur here b/c most K are open and most Na are inactive

Relative-some ap's can occur. However they will be smaller b/c some Na are inactive and some k channels are open
Define the patch clamp technique
Inserting two electrodes to measure the voltage across a section of an axon
Describe the general structure and properties of cell membranes
Permeable to water & hydrocarbon-like molecules (uncharged molecules)

Nonpermeable to ions, proteins (charged molecules)
List the type and concentration of some the key ions in cells and the extracellular fluid
Outside Inside
Na+ 140mM 10mM
K+ 4mM 140mM
Ca2+ 2.4mM 50nM
Define osmotic equilibrium
A permeant solute is in osmotic equilibrium when there's = [] inside and outside the cell.

A cell is in osmotic equilibrium if the extracellular and intracellular []'s of ALL impermeant solutes are equal.
Define the Nernst potential and compute is value
Nernst Potential = the ion equillibrium potentil. the "force of diffusion".

= 61/(valence of ion) x log [external conc. /internal conc.]
Steps in Nerve Physiology
1) How Membrane Potentials are Generated
2) How voltage gates Na/K Channels work
Describe the general topology of v-gated K & Na channels
They are proteins with a hole in it that will open if the plasma membrane is depolarized. There are 6 alpha helix membrane spanning parts. Every third aa is + (it's a voltage sensor).
What is an action potential
A temporary reversal of polarity in the membrane potential
How does axon diameter affect AP conduction velocity?
The larger the axon, the greater the velocity
Define the basic properties of myelin
It increases the action potential velocity as the action potentiol jumps from node to node. Very little conduction is lost to background channels.
What are background channels?
They are non-voltage gated ion channels that leak ions and therefore help set the resting membrabe potential. These channels cause the resting potential to be more positive than the Nernst potential.
How does the action potential propogate?
It's "boosted" by Na channels every so often so it doesn't die out via leakage via background channels.
What causes the symptoms of multiple sclerosis?

What can make it worse?
The Demylenation of axons results in:
slow conduction or worse, no conduction.

elevated temperature (such as fever) can exacerbate the symptoms.

It's likely an autoimmune disease of unknown etiology.

Always affects Causasions and women 2:1.
Define Pharmacology
The study of the interaction of chemicals wiht biological systems
Define Pharmokinetics vs. Pharmodynamics
Kinetics = What the body does to the drub (absorbtion, excretion, distribution)

Dynamics = What the drug does to the body (effects and mech of action)
The dynamics are more dynamic, in my opinion.
What do most drugs interact with?
A protein within the cell or on the surface of a cell
Give some examples of common proteins that drugs affect
Enzymes, transporters, ion channels, receptors. Two kinds of receptor effects: agonists turn on receptors, antagonists block receptors.
Define pharmotherapeutics
The use of drugs to prevent and treat disease
Definie Toxicology
Study of the adverse affects of chemicals or drugs
Clinical pharmacology
Study of drug effects on humans
What are the different types of names for drugs?
Chemical-acetylsalicyclic acid
Generic-Aspirin (decided by U.S. Committee)
Trade-Brand name
What are the adverse effects of thalidomide
It caused horrible malfornations in the children of preganant women who took the drug in the early 60's. It was an anti-depressant.
Steps on modern drug development
1) Drug Discovery (serendipidous, rational, screening of animals)
2) Preclinical drug eval (animal testing, LD 50 determined (lethal dose for 50% of individuals), toxicity)
3) Clinical drug eval- Investigatinal New Drug app to the FDA and Clinical Trial
Phases of Clinical Trials
1- Dose response, toxicity on healthy humans
2- efficacy in sick patients
3- randomized, controlled trial
4-avail to prescribers