Untitled Quiz

Solutes move directly through the lipid bilayer or via aqueous pores without the need for energy.

Primary active transport directly uses ATP to move solutes, while secondary active transport relies on the gradients created by primary active transport.

Aquaporins are water channels that facilitate rapid water transport across the cell membrane.

<p>The sodium-potassium pump (Na+/K+ ATPase) is an example of primary active transport.</p> Signup and view all the answers

<p>Electrical gradients create potential differences across the membrane, influencing the movement of charged ions.</p> Signup and view all the answers

<p>Osmolality measures the concentration of solutes in a solution, important for regulating fluid balance.</p> Signup and view all the answers

<p>Concentration gradients drive the passive movement of solutes, creating an equilibrium across membranes.</p> Signup and view all the answers

<p>Water transport is primarily regulated by aquaporins and osmotic gradients.</p> Signup and view all the answers

<p>Sodium (Na+) and potassium (K+) have notable concentration differences, with high Na+ outside and high K+ inside cells.</p> Signup and view all the answers

<p>Glucose would use facilitated diffusion through specific transporter proteins in the membrane.</p> Signup and view all the answers

<p>The Nernst equation calculates the equilibrium potential for K+, which is essential in determining the driving force influencing K+ movement during action potentials, particularly during repolarization when the potential changes drastically.</p> Signup and view all the answers

<p>Fick's Law states that the flux of a solute is inversely proportional to the membrane thickness; thus, a thinner membrane enhances the rate of solute diffusion.</p> Signup and view all the answers

<p>The lipid-water partition coefficient (Kp) indicates how easily a solute can dissolve in the membrane; higher Kp suggests better permeability, especially for hydrophobic substances.</p> Signup and view all the answers

<p>Active transport requires energy, usually in the form of ATP, to move substances against their concentration gradient, while passive transport relies on concentration gradients and does not require energy.</p> Signup and view all the answers

<p>Aquaporins are specialized membrane proteins that facilitate the rapid transport of water molecules across the cell membrane, enhancing water permeability.</p> Signup and view all the answers

<p>Weak acids and bases exist in ionised and un-ionised forms. The pKa is the pH at which 50% of the drug is ionised and 50% is un-ionised.</p> Signup and view all the answers

<p>Aspirin is primarily un-ionised in the stomach's acidic environment (pH 1.5), allowing it to diffuse across the gastric mucosal barrier, but it becomes ionised in the plasma (pH 7.4), trapping it in the bloodstream.</p> Signup and view all the answers

<p>Transmembrane concentration gradients drive simple passive diffusion by allowing substances to move from areas of higher concentration to areas of lower concentration until equilibrium is reached.</p> Signup and view all the answers

<p>Drugs with high lipid solubility, like Ganaxolone, readily diffuse across the lipid bilayer of the cell membrane, while those with low lipid solubility, like Mannitol, have more difficulty.</p> Signup and view all the answers

<p>The principal sites of carrier-mediated transport include the gastrointestinal tract, blood-brain barrier, placenta, renal tubule, and biliary tract.</p> Signup and view all the answers

<p>Passive transport does not require energy and occurs down a concentration gradient, while active transport requires energy to move substances against their concentration gradient.</p> Signup and view all the answers

<p>Aquaporins are specialized channel proteins that facilitate the rapid transport of water across cell membranes, enhancing osmotic balance.</p> Signup and view all the answers

<p>Ionisation affects drug absorption by determining the proportion of un-ionised and ionised forms, which influences the drug’s ability to traverse cell membranes and reach target sites.</p> Signup and view all the answers

<p>They are lipid-soluble and can cross the membrane without energy.</p> Signup and view all the answers

<p>Aqueous diffusion occurs via channels and does not require energy, while facilitated diffusion involves carrier proteins and also does not require energy.</p> Signup and view all the answers

<p>Active transport requires energy to move solutes against their concentration gradient.</p> Signup and view all the answers

<p>Endocytosis involves the invagination of the membrane to form a vesicle that encases a molecule for internal release.</p> Signup and view all the answers

<p>Passive diffusion does not require energy as it moves along a concentration gradient, while active transport requires energy to move against it.</p> Signup and view all the answers

<p>Osmolarity determines the direction of water movement, with water moving toward the area of higher solute concentration.</p> Signup and view all the answers

<p>The solute's lipophilicity and the permeability of the membrane are key factors for passive diffusion.</p> Signup and view all the answers

<p>Transport of molecules via methods like diffusion would effectively cease without a concentration gradient.</p> Signup and view all the answers

<p>Facilitated diffusion is a process where carrier proteins help move molecules down their concentration gradient; glucose is a common example.</p> Signup and view all the answers