Correct answers are in bold, but be sure to read why the other answers are not correct.
- Think of a biological membranes as an oreo cookie. It is a lipid bilayer with 2 parts – the outer (or chocolate cookie part) is __________________ and the inner part (or the creamy part) is ____________________. (fill in the blanks)
- hydrophilic; hydrophilic
You’re half right! The outer parts of the plasma membrane, or lipid bilayer, are hydrophilic or water-loving because that end of the fatty acid is polar. The inner part of the fatty acid contains the carbon chain, which is non-polar, or hydrophobic (water-fearing). - lipophilic; hydrophilic
Sorry, you got it backwards. The outer parts of the plasma membrane, or lipid bilayer, are hydrophilic or water-loving because that end of the fatty acid is polar. The inner part of the fatty acid contains the carbon chain, which is non-polar, hydrophobic (water-fearing) or lipophilic (lipid-loving). - hydrophilic; hydrophobic
Terrific! The outer parts of the plasma membrane, or lipid bilayer, are hydrophilic or water-loving the that end of the fatty acid is polar. The inner part of the fatty acid contains the carbon chain, which is non-polar, or hydrophobic (water-fearing). - hydrophobic; amphoteric
Sorry! The outer parts of the plasma membrane, or lipid bilayer, are hydrophilic or water-loving because that end of the fatty acid is polar. The inner part of the fatty acid contains the carbon chain, which is non-polar, or hydrophobic (water-fearing).
- hydrophilic; hydrophilic
- Certain drugs cannot get into the brain very easily because of the presence of a “blood-brain barrier”. Lipophilic drugs like cocaine penetrate this protective barrier rather quickly, but charged compounds cannot. This is because the blood-brain barrier consists of:
- Tightly packed capillary epithelial cells
Sorry, that is incorrect. Epithelial cells are a type of skin cell. Capillaries in the brain contain tightly packed endothelial cells that prevent polar compounds from diffusing across the membrane into the brain (the “blood-brain barrier”). - Tightly packed capillary endothelial cells
Good answer! Capillaries in the brain contain tightly packed endothelial cells that prevent polar compounds from diffusing across the membrane into the brain (the “blood-brain barrier”). Lipophilic compounds diffuse easily across the capillaries. - Mucosal cell membranes
Sorry, that is incorrect. Mucosal cell membranes are a type of epithelial cell that secretes mucous (such as in the lining of the gut or the nose). Capillaries in the brain contain tightly packed endothelial cells that prevent polar compounds from diffusing across the membrane into the brain (the “blood-brain barrier”). Lipophilic compounds diffuse easily across the capillaries. - Very small sacs known as alveoli
Sorry, that is incorrect. Alveoli are special cells present in the lungs for the exchange of gases. Capillaries in the brain contain tightly packed endothelial cells that prevent polar compounds from diffusing across the membrane into the brain (the “blood-brain barrier”). Lipophilic compounds diffuse easily across the capillaries.
- Tightly packed capillary epithelial cells
- Research into the fields of drug abuse, pharmacology, and psychology indicates that the period of time between the introduction of a drug into the body and its ability to produce euphoria or pleasure is important in the abuse potential of that drug. A user is more likely to continue cocaine use after:
- Snorting the drug
Wrong answer. When snorted, cocaine must diffuse through mucosal cells lining the nasal passages into nearby capillaries, which allow its absorption into the blood stream rather quickly. However, the drug must then travel within the venous system to the heart, then to the lungs, and then back to the heart for distribution throughout the body, including the brain. - 2. Ingesting the drug
Wrong answer. Very little cocaine gets absorbed from the gut into the bloodstream because much of it is actually metabolized there. Only mild effects are produced and they occur very slowly, decreasing the abuse potential of this form of cocaine. - Smoking the crack form of the drug
Bravo! Because smoking crack allows the drug to enter the bloodstream almost instantly, the high is produced within seconds. The cocaine only needs to return to the heart from the lungs and then goes straight to the brain. Furthermore, cocaine leaves the brain very quickly after smoking stops, encouraging the user to repeat the process.
- Snorting the drug
- Cocaine is a molecule composed of C, H, O, and N atoms. In solution, the drug exists in two forms in an equilibrium: the free base and the acid salt; the pH of the environment determines the predominant form. The route of administration of cocaine depends on whether it is in the free base or acid salt form. The ionized or polar form (the salt) of cocaine can be administered into the body in which of the following manners?
- Snorted and smoked
You are partly right. The hydrochloride salt form of cocaine readily dissolves in solution, allowing the drug to be snorted or injected. However, the salt forms of weak bases like cocaine are destroyed by the high temperatures needed to make them volatile, so they cannot be smoked. - 2. Snorted, injected, and smoked
You got 2 out of 3 right! The hydrochloride salt form of cocaine readily dissolves in solution, allowing the drug to be snorted or injected. However, the salt forms of weak bases like cocaine are destroyed by the high temperatures needed to make them volatile, so they cannot be smoked. - 3. Injected and smoked
You are partly right. The hydrochloride salt form of cocaine readily dissolves in solution, allowing the drug to be snorted or injected. However, the salt forms of weak bases like cocaine are destroyed by the high temperatures needed to make them volatile, so they cannot be smoked. - Snorted and injected
You’re right! The hydrochloride salt form of cocaine readily dissolves in solution, allowing the drug to be snorted or injected.
- Snorted and smoked
- Drugs can be introduced into the body on the venous side or the arterial side of the circulatory system. Which side of the circulatory system does cocaine reach first, if it is snorted or smoked?
- arterial, venous
Guess again. Any drug that enters the circulation via capillaries outside the lungs will flow into the veins. After snorting cocaine, it enters capillaries in the nasal passages, then travels to the veins, which bring it to the right side of the heart. In contrast, smoked cocaine enters capillaries in the lungs, that contain oxygenated blood, which returns to the left side of the heart, to be pumped through the arterial system throughout the body. - arterial, arterial
Guess again. Any drug that enters the circulation via capillaries outside the lungs will flow into the veins. After snorting cocaine, it enters capillaries in the nasal passages, then travels to the veins, which bring it to the right side of the heart. In contrast, smoked cocaine enters capillaries in the lungs, that contain oxygenated blood, which returns to the left side of the heart, to be pumped through the arterial system throughout the body. - venous, arterial
Terrific! Any drug that enters the circulation via capillaries outside the lungs will flow into the veins. After snorting cocaine, it enters capillaries in the nasal passages, then travels to the veins, which bring it to the right side of the heart. In contrast, smoked cocaine enters capillaries in the lungs, that contain oxygenated blood, which returns to the left side of the heart, to be pumped through the arterial system throughout the body. - venous, venous
Guess again. Any drug that enters the circulation via capillaries outside the lungs will flow into the veins. After snorting cocaine, it enters capillaries in the nasal passages, then travels to the veins, which bring it to the right side of the heart. In contrast, smoked cocaine enters capillaries in the lungs, that contain oxygenated blood, which returns to the left side of the heart, to be pumped through the arterial system throughout the body.
- arterial, venous
