Shared Flashcard Set

Details

Week 3
regulating cell environments
78
Biology
Graduate
08/30/2008

Additional Biology Flashcards

 


 

Cards

Term
Is the interior of the cell electrically negative or positive with respect to the extracellular fluid?
Definition
Negative
Term
The dominant factor in determining the permeability of a membrane to a substance is the electrostatic interaction of the solute with _____?
Definition
Water, because intermolec forces are stronger between water than lipids
Term
True or false: There is a direct relationship of the number of H-bonds a molecule has and its membrane solubility.
Definition
False, inverse
Term
What accounts for greater solute permeability in increasingly sized hydrocarbons?
Definition
Hydrophobic bonding due to additional methylene groups
Term
Why can you increase the rate of drug transport by simply changing non-essential substituent groups to a molecule?
Definition
Because diffusion across the bilayer accounts for the greatest permeation of drugs in the body
Term
There are two classes of aquaporins(AQPs) what are they and what do they do?
Definition
Orthodox, water-selective with unique tissue distribution; multifunctional, allow for water, glycerol, urea, small molecs to pass thru.
Term
The water permeability of a plasma membrane depends on what 2 things?
Definition
Permeability of the lipid, and type/density of AQPs
Term
How does Vasopressin work?
Definition
Controls reabsorption of water in the kidneys by recruiting AQPs to cell membranes
Term
What are the three functional groups of solute transporters or carriers?
Definition
Uniporters/facilitated transporters move molecules down a gradient like glucose in blood brain barrier; Cotransporters/symport/antiporters/secondary active uses the energy of electrochem gradient of one molecule to move another, like symport Na/Glucose in intestinal lining or Cl/HCO3 in RBCs; exchangers/active transporters use ATP to move stuff up gradient like Na/K pump
Term
Despite the potential for molecules to move across a membrane, what 3 things limit the actual transport rate?
Definition
Substrate concentration, affinity for substrate to carrier, rates of conversion
Term
What is the most prevalent active transport/antiport carrier?
Definition
Na/K pump
Term
What is the most important cotransport/symport carrier?
Definition
Na/Glucose
Term
The most important aspect of the intestinal Na/glucose transporter is oral rehydration therapy, what is that?
Definition
It is a solution of salts and glucose to have the body actively restore lost fluid due to the questions mechanism.
Term
These three transporters are from what type of mechanism: Cl/HCO3 (red blood cell), Na/H (pH balance), Na/Ca (cardiac muscle)?
Definition
Antiporter/exchanger
Term
What type of cells form a barrier between the body and the external world, ie skin, lungs, GI, renal tubule, blood brain barrier?
Definition
Epithelial cells
Term
In general epithelia tight junctions have variable resistances to molecules, so what 2 classifications of epithelia are there?
Definition
Leaky, tight
Term
What ion regulates tight junction adherence?
Definition
Calcium, more makes it stronger bond and less leaky
Term
The low resistances of ion flows in epithelia are mainly due to what?
Definition
How strong tight junctions are.
Term
The urinary bladder, stomach, and renal collecting tubule have low epithelial resistances and small gradients?
Definition
No, high resistance/gradients
Term
Name 3 organ epithelia that have ion flow reistance.
Definition
Renal proximal tubule, intestine, gall bladder, choroids plexus
Term
What is so unique about the distribution of membrane proteins in epithlia versus other cells?
Definition
In epithelia, membrane proteins are sorted in the trans-golgi face and put in transport vesicles to the apical and basolateral surfaces.
Term
What does this mean: epithelial cells are polarized?
Definition
There is a difference in structure and function between the apical and basolateral membranes of epithelia
Term
Water transport is directly proportional to what?
Definition
Active solute transport
Term
What area of epithelia creates a local osmotic gradient driving water in?
Definition
intracellular spaces have many ions driving water into the cells
Term
True or False: the ion gradient and selective permeability alone can create a potential difference in the cell.
Definition
True
Term
Which of these ions have either high or low concentrations inside the cell: K, Cl, Na, Ca.
Definition
K is higher inside cell, rest high outside cell
Term
What type of molecules diffuse into the cell without assitance?
Definition
Hydrophobic
Term
What is equilibrium potential in a cell?
Definition
The voltage at which the net flow of ions is zero.
Term
Pharmokinetics
Definition
the interrelationships between the absorption, distribution, metabolism, excretion, and its concentration at the site of action.
Term
Pharmacodynamics
Definition
biochemical effects of drugs, metabolism, relation between drug concentrations and biological effects
Term
Quantal response
Definition
the fraction of the population that responds to a given dose, ie LD/ED/TD50
Term
Therapeutic index
Definition
TD or LD divided by ED
Term
Therapeutic window
Definition
range of doses that is sufficient to provide efficacy but not toxicity
Term
Agonists
Definition
drugs that bind to receptors and mimic endogenous signaling compound
Term
Agonist efficacy
Definition
maximal response achievable with drug; like full agonist or partial agonist
Term
Agonist potency
Definition
effective dose that produces 50% of max efficacy
Term
Antagonists
Definition
drugs that bind to receptors but do not produce response, inhibitors
Term
Competitive antagonist
Definition
drug binds to same site on receptor as natural signal compound
Term
Noncompetitive antagonist
Definition
drug binds to site other than that of natural signal compound
Term
Irreversible antagonist
Definition
drug that causes a conformational change in receptor that is irreversible
Term
What is the dissacociation rate constant, Kd, refer to in pharmacology?
Definition
The affinity of a drug for a receptor or concentration needed to occupy 50% of receptor pool
Term
Elaborate on the 5 receptor regulation responses to drugs: desensitization/tachyphlaxis, tolerance, sensitization, down-regulation, up-regulation
Definition
effect diminishes with continued exposure, gradual decrease in response, increase in responsiveness, decrease of receptor number, increase receptor number
Term
List the 4 major types of drug-receptor complexes in order from slowest to fastest.
Definition
Control of DNA transcription, direct control of effector enzyme, indirect G protein coupling via 2nd messengers, direct control of ion channel
Term
Pharmokinetic processes
Definition
each process of absorption, distribution, metabolism, elimination is governed by defined factors
Term
Drug absorption
Definition
movement of drug from site of administration to the plasma compartment
Term
Differentiate the two routes of drug absorption.
Definition
Parenteral - non-gi administration, enteral - gi, oral, rectal
Term
Describe the 3 ways drugs cross membranes.
Definition
Transmembrane protein recognizes substrate and moves it across (ATP dependent, regulated), pinocytosis, diffusion
Term
What is ion trapping?
Definition
A higher buildup of a drug across a membrane due to the difference in pH across surfaces and pKa value of drug, non-ionized forms pass membrane more readily. Weak acids absorbed by acidic areas like stomach, weak bases taken by basic areas like small intestine
Term
What is enterohepatic circulation?
Definition
First pass of drug gets metabolized through liver before general circulation
Term
What types of drugs pass the blood-brain barrier?
Definition
Low polarity (carrier mediated) or neutral non-polar compounds
Term
What happenes in a phase 1 and 2 drug metabolism?
Definition
Phase 1 - a polar function is introduced to reaction (CYP oxidation), phase 2 - substrate (phase 1 metabolite)is coupled to endogen compound making it more polar (glucuronidation)
Term
Why is it necessary to metabolize drugs and make them more polar?
Definition
The greater the polarity, more water soluble, more easily excreted
Term
Where is the most important metabolic enzyme, CYP450, located in the cell and highest concentration in body?
Definition
ER membrane, liver
Term
What 3 things can affect drug enzyme availability?
Definition
Age (old/young have less enzymes), genetics (natural variations in enzyme production), environment (chemicals induce or inhibit enzymes)
Term
What is difference in metabolic enzyme induction and inhibition by drugs?
Definition
Induction increases production of enzyme quantity and inhibition is created when there is competition for binding sites on enzyme
Term
Is CYP a phase 1 or 2 enzyme?
Definition
1
Term
What is the consequence of induction or inhibition?
Definition
More metabolism and less drug in system, less metabolism and more drug in system
Term
As far as physicians are concerned, what is the importance of confidence intervals and p values?
Definition
It simply describes a range of plausible values from sample size that apply to population that are not impacted by chance alone other than extremes (p-values).
Term
What would does a 95% CI mean in real terms?
Definition
If the study were conducted over and over again, 95% of results would have true values.
Term
In observation studies, what does confounding refer to?
Definition
The influence of factors associated with exposure being studied and outcome measured, ie study design, lack of complete info in retrospective studies
Term
What is bioavailability?
Definition
The fraction of administered does that reaches circulation
Term
Pharmaco: what is the area under the curve of a bioavailability curve?
Definition
It is amount of bioavailability.
Term
Pharmaco: what is volume of distribution?
Definition
The apparent volume of fluid to contain the total amount of drug, i.e. its solubility in the body
Term
Bioequivalence?
Definition
Two drugs that are similar in efficacy and safety in bioavailability
Term
How does the volume of distribution affect blood concentration of drugs?
Definition
Larger Vd, spreads farther through body, longer to eliminate, need more drug to maintain blood-drug levels
Term
What are the 3 fundamental processes for renal excretion?
Definition
Glomuler filtration, proximal tube excretion, passive reabsorption at distal tubule
Term
First order elimination?
Definition
Elimination is based on drug concentration, same fraction is lost over interval of time
Term
Zeroeth order elimination?
Definition
Elimination is constant due to metabolic saturation, constant amount is lost over a given interval
Term
What is a one-compartment model?
Definition
A model based on a drug filling one compartment and it is eliminated linearly from that single area
Term
What is a two-compartment model?
Definition
A model based on a drug filling one area, and perfusing to a second compartment, so drug is initially lost linearly from the main compartment(blood, organs), then at a slower rate as the drug moves from the second compartment(peripheral tissues) to the first
Term
What is the difference between alpha and beta phases in a two compartment model?
Definition
Alpha is intial distribution and elimination in main compartment, beta is elimination from main compartment by diffusion from second compartment
Term
What is clearance?
Definition
The volume of drug cleared from plasma per unit of time
Term
What is steady state drug concentration?
Definition
The rate of infusion of drug is equal to rate of clearance
Term
What is capacity limited elimination?
Definition
A zero order kinetic elimination where there is a max of drug that can be eliminated per amount of time
Term
Define these: dyspnea, purulent, bronchiectasis.
Definition
Shortness of breath, puss-filled, localized dilation of bronchial tree
Term
How many molecules of ATP are necessary to complete one cycle of a Na/K pump?
Definition
1
Term
What does the Nernst equation describe?
Definition
The membrane potential regarding only one ionic species
Term
What is the partition coefficient of a drug?
Definition
The distribution between lipid and aqueous phases
Supporting users have an ad free experience!