Pharmacology Membrane Transport Quiz

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Questions and Answers

Which statement correctly differentiates active transport from passive diffusion?

Passive diffusion requires protein receptors to facilitate movement.

Active transport cannot be saturated.

Both move only down the concentration gradient.

Active transport requires energy and can move up the concentration gradient. (correct)

What is a key characteristic of transcellular drug absorption?

Drugs pass through the space between cells.

It requires specific protein receptors for the movement. (correct)

It can occur regardless of drug size.

Drugs diffuse only along electrochemical gradients.

Which of the following factors does not affect paracellular absorption?

Presence of lipid bilayer. (correct)

Size of the drug molecule.

Size of the pores between cells.

Concentration gradient of the drug.

Why is Enhanced Permeability and Retention (EPR) critical in drug delivery to tumors?

It enables nanoparticles to accumulate in tumor tissues more effectively. Signup and view all the answers

Which of the following statements about facilitated transport is accurate?

It relies on specific carrier proteins for the transport of molecules. Signup and view all the answers

What is a key characteristic of passive diffusion in drug absorption?

It is non-specific and relies on lipid solubility. Signup and view all the answers

Which of the following best describes active transport mechanisms?

They are specific for certain molecules and can become saturated. Signup and view all the answers

What is the primary function of carrier-mediated transport in drug absorption?

To recognize and bind specific molecules for transport. Signup and view all the answers

In transcellular absorption, what is primarily required for drugs to pass through membranes via active transport?

Affinity for the carrier protein. Signup and view all the answers

Which statement is true concerning membrane channels in drug transport?

They provide a specific pathway for certain molecules to enter or leave cells. Signup and view all the answers

What distinguishes facilitated transport from passive diffusion in drug absorption?

Facilitated transport is specific for particular molecules. Signup and view all the answers

Which factor does NOT affect the rate of drug absorption through passive diffusion?

The availability of transporter proteins. Signup and view all the answers

Which transport mechanism requires the input of ATP for drug movement?

Carrier-mediated active transport. Signup and view all the answers

Which mechanism allows substances to pass through the cell membrane by utilizing specific carriers?

Facilitated transport Signup and view all the answers

What is one effect of agents that block transport proteins?

Prevent neurotransmitter reuptake Signup and view all the answers

Which type of transport is primarily responsible for the movement of substances across the cell membrane without the use of energy?

Facilitated diffusion Signup and view all the answers

Which mechanism of drug absorption is most likely affected by competitive inhibition?

Transcellular absorption Signup and view all the answers

In what way does methylphenidate function as a reuptake inhibitor?

It enhances communication between neurons by blocking reuptake. Signup and view all the answers

Which statement about passive diffusion is true?

It does not require energy and substances move down their concentration gradient. Signup and view all the answers

Which of the following types of membrane transport would be affected by a change in temperature?

Facilitated diffusion Signup and view all the answers

What is a common effect of drugs that act as reuptake inhibitors like cocaine?

Euphoric effects and increased neurotransmitter levels Signup and view all the answers

Study Notes

Membrane Transport

Passive Diffusion: Drug molecules pass through the membrane based on their lipid solubility. Lipid solubility is directly proportional to the lipid/water partition coefficient of the drug.
Channel Transport: Specific for certain molecules, requiring binding recognition.
Carrier-mediated transport: Specific for certain molecules, requiring binding recognition.

Transcellular Absorption

Passive Diffusion: Down the concentration gradient.
Channel Transport: Down the concentration gradient.
Carrier-mediated transport: Down the concentration gradient.

Active Transport

Carrier mediated active transport: Against a concentration gradient or an electrochemical gradient; can become saturated at high concentrations.
Active Transport: Through transporter proteins; specific, saturable. Examples include Iron transport in the gut, L-DOPA transport across the blood-brain barrier, and anion/cation transport in the kidney.

Paracellular Absorption

Dependent on the size of the drug (molecular weight less than 200) compared to the size of the cellular pore.
Non-specific, allowing anything of the appropriate size to pass.
Passive: down the concentration gradient or electrochemical gradient.
Does not move through the lipid bilayer.

Nanoparticle Characteristics

Smaller in size compared to small-molecule drugs.
Have different physical and chemical properties compared to small-molecule drugs.

Enhanced Permeability and Retention (EPR) Effect

Key feature of nanocarrier delivery to tumors.
Utilizes passive mechanisms of EPR – a critical design parameter of nanocarrier delivery.
Pore size in the endothelial walls determines the entry of nanoparticles into tissues.

Competitive Inhibition

Membrane passage via transport mechanisms is subject to competitive inhibition by another substance with similar affinity for the same carrier.

Agents Blocking Transport Proteins

Agents binding to transport proteins prevent re-uptake of neurotransmitters.
Examples include:
- Methylphenidate (Ritalin) – reuptake inhibitor for dopamine and noradrenaline.
- Cocaine – reuptake inhibitor for dopamine and serotonin.

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Description

Test your knowledge on the various processes involved in membrane transport, including passive diffusion, channel transport, and active transport mechanisms. This quiz covers key concepts on drug absorption and transport across cellular membranes, highlighting their significance in pharmacology.