Week 2

Question 1

What type of compounds are able to pass through the lipid bilayer

Answer 1

Lipid-soluble compounds (including most drugs)

Question 2

How do non-lipid soluble substances pass through the cell membrane

Answer 2

Non Lipid Soluble substances, including water, can pass through from one side of the membrane to the other because of the presence of membrane pores.

Small holes or channels exist in the membrane, thereby allowing certain substances to pass from one side of the membrane to the other.

These channels are typically formed by some of the membrane proteins that span the width of the membrane

Question 3

The ability of a substance to pass through a specific pore depends primarily on (2)

Answer 3

1. the size, shape, and electrical charge of the molecule.
2. Also, in excitable membranes (nerve, muscle), some of these pores are dynamic in nature and can “open” and “close” to regulate the flow of ions, such as sodium, potassium, and chloride, in and out of the cell.
   (These dynamic ion channels are especially important in pharmacology because many drugs can affect their ability to open and close. By regulating the movement of ions across the cell membrane, the drugs can alter cell excitability.)