What is the relationship between concentration and transport in carrier-mediated transport?
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As concentration increases, transport also increases until a maximum is reached.
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What is the relationship between concentration and transport in carrier-mediated transport?
As concentration increases, transport also increases until a maximum is reached.
What type of transport is characterized as not saturable?
Passive transport.
What type of transport does channel-mediated diffusion represent?
It does not use energy.
What is a characteristic of channel-mediated transport regarding cell membrane layers?
There is no penetration of the layers of the cell membrane.
What physiological process is associated with calcium in channel-mediated transport?
Contraction.
What does membrane thickness refer to?
The distance a molecule has to traverse from the absorption surface to a blood capillary.
What is the relationship between membrane thickness (MT) and absorption?
Increased MT leads to decreased absorption, while decreased MT leads to increased absorption.
What is required for active transport mechanisms?
Energy.
What limits the transport in carrier-mediated transport?
Saturation of the transport mechanism.
What do efflux transporters do?
They transport molecules out of the cell.
What is the function of a substrate in drug transport?
A substrate is pushed out of the cell by a transporter.
What is the n-octanol/water partition coefficient used for?
It is a common measure of lipophilicity.
What is the specific term used to describe the processes that facilitate drug movement across membranes?
Drug transport.
What is another name for active transport mechanisms?
Concentrating Transporters.
What is the relationship between drug size and lipophilicity to permeability?
Larger and more lipophilic drugs generally have higher permeability.
What are the three main types of active transport mechanisms?
Pumps, Concentrating Transporters, and Endocytosis.
What is pinocytosis?
Pinocytic uptake in which molecules enter the cell as part of the fluid phase.
What is required for molecules to enter circulation through active transport?
They need to pass through several membranes.
What is carrier-mediated transport?
A process that involves proteins to facilitate the movement of substances across a membrane.
How do carrier proteins assist in drug transport?
They help facilitate the movement of drugs across membranes.
Does passive diffusion require energy?
No, it does not use energy (ATP).
What is the formula for the net rate of permeation in passive diffusion?
Net rate of permeation = P × SA × (Cu1 - Cu2)
What type of energy is typically used in active transport?
ATP (adenosine triphosphate).
Can active transport occur without the presence of a membrane protein?
No, it typically requires specific carrier proteins or pumps.
How does permeability relate to drug transport?
Permeability is crucial for the effective transport of drugs across cell membranes.
What characterizes clathrin-mediated endocytosis?
Large extracellular molecules have receptors on the cell.
What type of molecules does endocytosis primarily involve?
Larger molecules.
What is the structure of the cell membrane?
Phospholipid bilayer.
What is the difference between influx and efflux transport?
Influx is the uptake of substances into the cell, while efflux is the outward transport of substances from the cell.
What is the driving force for active transport?
Against the concentration gradient.
How does drug size affect permeability?
Larger drug size generally decreases permeability.
What is the primary focus of drug transport mechanisms?
Membrane permeability.
What are the two main pathways for drug transport across membranes?
Paracellular and transcellular pathways.
What can pass through channel-mediated transport?
Anything could go in or out, including water.
Which ion is specifically mentioned in relation to channel-mediated transport?
Calcium.
What is passive diffusion?
The movement of water-soluble molecules or drugs across the plasma membrane without the use of energy.
What is the title of the course offered at Saint Louis University?
Biopharmaceutics and Pharmacokinetics.
Which organs are mentioned in relation to passive diffusion?
Kidney and Brain.
What type of molecules are transported via active transport?
Lipid insoluble molecules; high molecular weight.
What happens to co-transported molecules in facilitated diffusion?
They can compete and inhibit each other.
What is the typical thickness range for cell membranes?
0.005 to 0.01 micrometers.
What is meant by 'transport maximum' in carrier-mediated transport?
The maximum rate of transport that can be achieved when all carriers are saturated.
How does active transport differ from passive transport?
Active transport requires energy, while passive transport does not.
Who compiled the course material for PHARM 314?
Cristopherson P. Mata, RPh, MS Pharm.
Which edition of 'Essentials of Pharmacokinetics and Pharmacodynamics' is referenced?
2nd edition.
What is paracellular drug transport?
The passage of drug through aqueous channels.
What is metabolism in the context of drug action?
Biotransformation of drugs in the body.
What role do proteins play in carrier-mediated transport?
They help move substances across the membrane.
What is the natural tendency of molecules in passive diffusion?
To move down a concentration gradient.
What are the key drug properties that determine passive permeability?
Drug size, lipophilicity, and charge/degree of ionization.
How does urine acidification affect drug absorption?
It can enhance the absorption of weak bases by creating a more favorable environment for their unionized form.
What is phagocytosis?
Adsorptive or phagocytic uptake of particles that have been bound to the cell membrane surface.
What is the process of drug absorption?
Drugs pass through the gut wall.
What are the two main types of carrier-mediated transport?
Facilitated diffusion and active transport.
What is the solubility of hydrophobic substances in water?
They are not soluble in water.
What is the role of kinetic energy in passive diffusion?
Kinetic energy drives the movement of molecules across the membrane.
What is the relationship between lipophilicity and drug absorption?
Increased lipophilicity leads to increased absorption.
What is a characteristic of carrier-mediated transport regarding specificity?
It is specific to certain molecules.
What is a common type of molecule transported by active transport?
Nucleosides.
What is the focus of UNIT 4 in the PHARM 314 course?
Drug Transport Mechanisms.
What is an important factor mentioned in the context of drug transport?
Membrane.
What are the main components of the cell membrane?
Phospholipids, cholesterol, and proteins.
What are aquaporins?
Membrane proteins that facilitate the passive transport of water across cell membranes.
What is the driving force for passive diffusion?
Concentration gradient.
Is facilitated diffusion saturable?
No, it is not saturable and occurs until equilibrium is reached.
What is the most common transport mechanism for drugs?
Most drugs use passive diffusion.
What are influx transporters responsible for?
They allow molecules to enter the cell.
What role do pumps play in drug transport in the brain?
Pumps transport drugs out of the brain, affecting drug permeability.
What do hydrophilic and hydrophobic refer to?
Hydrophilic refers to substances that attract water, while hydrophobic refers to substances that repel water.
What does a higher partition coefficient indicate?
The substance or drug is more lipophilic.
What is transcellular drug transport?
The passage of drug through cells.
What is a limiting factor for drug permeation?
Membrane thickness.
What is the process of drug excretion?
Passive filtration of drugs from the body.
Where are the hydrophilic heads of phospholipids located?
Towards the aqueous environment.
What factors determine passive permeability of drugs?
Drug size, lipophilicity, and charge/degree of ionization.
What is active transport?
A process that moves molecules against their concentration gradient using energy.
What is the primary function of active transport in cells?
To maintain concentration gradients of ions and molecules across the cell membrane.
What is an example of active transport in human cells?
The sodium-potassium pump (Na+/K+ pump).
In what environment do weak bases permeate more easily?
In an acidic environment.
Why is the small intestine significant for drug absorption?
It has a high surface area, which allows for better absorption.
What is the role of receptors in endocytosis?
They are necessary for the selective uptake of molecules.
How do hydrophilic substances behave in non-polar solvents?
They are very insoluble in non-polar solvents.
What type of environment do hydrophobic molecules prefer?
Non-polar solvents.
How does passive diffusion differ in terms of saturation?
It is not saturable.
How thick can membranes be at some skin sites?
Several millimeters.
What does the pH partition hypothesis state?
Only unionized nonpolar drugs penetrate the membrane, and at equilibrium, their concentrations are equal on both sides.
What type of drugs have better absorption through passive diffusion?
Non-polar drugs.
What must all drugs do to elicit a systemic response?
Pass through one or more membranes between the site of administration and the site of action.
What is one of the sources for the course material?
Applied Biopharmaceutics and Pharmacokinetics by Shargel, Leon.
What does drug distribution refer to?
The delivery of drugs into the target site of action.
How does facilitated diffusion differ from active transport?
Facilitated diffusion does not require energy, while active transport does.
What does it mean for a membrane to be 'hard to cross'?
It indicates that only specific types of substances can pass through, often requiring them to be lipophilic.
What does 'P' represent in the permeation formula?
Permeability.
Why do polar drugs have less absorption?
Because they are less able to penetrate the membrane.
What are the four main processes drugs undergo in the body?
Absorption, Distribution, Metabolism, and Excretion.
Which edition of 'Basic and Clinical Pharmacology' is cited?
13th edition.
What is a key characteristic of membranes regarding passive diffusion?
Membranes have specific properties that affect the ability of substances to cross them.
What type of substances must be to cross certain membranes?
Lipophilic (fat-soluble) substances.
What is the behavior of lipophobic substances in the cell membrane?
They fail to interact with hydrophobic environments.
How does membrane thickness affect absorption?
Increased membrane thickness decreases absorption.
What role do membrane channel proteins play in facilitated diffusion?
They serve as selective pores through which water crosses the plasma membrane.
What type of molecules are transported via passive diffusion?
Lipid soluble molecules; low molecular weight (200 - 1000 g/mol).
What is the relationship between partition coefficient and lipophilicity?
An increase in partition coefficient leads to an increase in lipophilicity.
What is a key characteristic of active transport?
It is energy dependent (ATP).
What is the significance of the environment's pH for drug ionization?
Weak acids may ionize in alkaline environments, affecting absorption.
What characteristic does the cell membrane exhibit?
Semi-permeability, allowing selective passage of substances.
Which drugs are transported via passive diffusion?
Lithium, Furosemide, Vitamin C, and Caffeine.
Is energy required for facilitated diffusion?
No, it is non-energy dependent.
How does saturation occur in facilitated diffusion?
It is saturable at high concentrations.
