What did I learn? Score Your Quiz (Module 2)

1. In this module, you learned that hair color might affect the outcome of drug testing. A dark-haired man and a blonde man use cocaine one night at the same time. Upon drug testing one month later, the dark-haired man is denied employment while the blonde man is hired. This happens because the dark-haired man:
   

   1. Has more keratin in his hair follicles
      Try again.  Keratin, a fibrous protein, is responsible for the strength and structure of hair.  Melanin, a polymer, provides the pigment that gives hair color.  Darker hair contains more melanin than lighter colored hair.  Melanin, which is acidic, binds to weak bases such as cocaine.  Therefore, the more melanin present, the more binding of cocaine.
   2. Has less keratin in his hair follicles
      Try again.  Keratin, a fibrous protein, is responsible for the strength and structure of hair.  Melanin, a polymer, provides the pigment that gives hair color.  Darker hair contains more melanin than lighter colored hair.  Melanin, which is acidic, binds to weak bases such as cocaine.  Therefore, the more melanin present, the more binding of cocaine.
   3. Has more melanin in his hair follicles
      Correct!  Melanin, a polymer, provides the pigment that gives hair color.  Darker hair contains more melanin than lighter colored hair.  Melanin, which is acidic, binds to weak bases such as cocaine.  Therefore, the more melanin present, the more binding of cocaine.
   4. Has less melanin in his hair follicles
      Try again.  Melanin, a polymer, provides the pigment that gives hair color.  Darker hair contains more melanin than lighter colored hair.  Melanin, which is acidic, binds to weak bases such as cocaine.  Therefore, the more melanin present, the more binding of cocaine.
2. Cocaine, a weak base, can be found in hair. Once in the bloodstream, cocaine can cross the capillary membranes to enter the hair follicle and bind to melanin. Its ability to bind to melanin, an acid, is because it can:
   1. Remove a hydrogen ion, H+, from the melanin
      Good answer!   Cocaine, a weak base, accepts a hydrogen ion from melanin, and this causes the cocaine to become a charged molecule.  Charged molecules are not able to cross back very easily into capillary membranes found near hair follicles.
   2. Remove a hydroxide ion, OH-, from the melanin
      Sorry, that is incorrect. Cocaine, a weak base, accepts a hydrogen ion from melanin, and this causes the cocaine to become a charged molecule.  Charged molecules are not able to cross back very easily into capillary membranes found near hair follicles.
   3. Add a hydroxide ion, OH-, to the melanin
      Sorry, try again.  Cocaine, a weak base, accepts a hydrogen ion from melanin, and this causes the cocaine to become a charged molecule.  Charged molecules are not able to cross back very easily into capillary membranes found near hair follicles.
   4. Add a hydrogen ion, H+, to the melanin
      Sorry, that is incorrect.  Cocaine, a weak base, accepts a hydrogen ion from melanin, and this causes the cocaine to become a charged molecule.  Charged molecules are not able to cross back very easily into capillary membranes found near hair follicles
3. This module reminded you that drugs can enter the body in different ways. Drug addicts avoid using methods of administration that result in slow entry into the body or bloodstream because they need to feel the effect of the drug quickly. By which of the following forms of adminstration does a drug get into the bloodstream slowest?
   1. Injection into a vein
      No.  Injecting a drug directly into a vein is actually the quickest way to get it into the bloodstream.  Once in the veins (deoxygenated blood), the drug travels to the right heart, goes to the lungs, and then the oxygenated blood returns to the left heart, where it is pumped through the arterial system to reach all tissues.
   2. Snorting it
      Incorrect.  Snorting a drug allows the drug to enter the venous system somewhat rapidly, but more slowly than injecting it.  Once in the veins (deoxygenated blood), the drug travels to the right heart, goes to the lungs, and then the oxygenated blood returns to the left heart, where it is pumped through the arterial system to reach all tissues.
   3. Smoking it
      Try again.  Smoking is almost as fast as injection in order to get a drug into the blood. When crack is smoked, it moves easily from the lung tissue into arteries (with oxygenated blood) that go back to the left heart.  Upon leaving the left heart via the aorta, the drug is pumped through the arterial system to reach all tissues.
   4. Ingestion (by mouth)
      You’re right!  A drug that is ingested travels from the gut to the liver first.  A portion of the drug is metabolized (destroyed) as it passes through the liver. As it leaves the liver, the drug travels through the venous system to the right heart, then the lungs, and then back through the left heart, where it is pumped through the arterial system to reach all tissues. This takes extra time compared to all other forms of drug administration.
4. A drug test is given to a woman applying for a job. The interviewer tells her that traces of cocaine were found in her hair. She claims that she has not used any of the drug. She said it must be because she was near someone who was smoking crack. Upon further investigation, the interviewer believes her because:
   1. Metabolites of cocaine were found in her hair shaft
      Sorry, that isn’t correct.  If metabolites of cocaine were found in the woman’s hair shaft, that would indicate that the drug had entered her bloodstream, it was metabolized and the metabolites entered the hair follicles.  Thus, she must have used cocaine.
   2. She had a high level of melanin in her hair
      Sorry, try again.  The amount of melanin in hair does dictate how much cocaine will bind to the hair; more melanin means more binding of cocaine.  However, this would not answer the question of how the drug got into the person’s hair.
   3. There was no real pattern of cocaine binding to the hair
      Correct!  When a person is exposed to smoke containing drugs like cocaine, heroin or nicotine, these lipophilic compounds can easily penetrate the hair shaft and bind to melanin.  The length of hair that is exposed to the air during the exposure time will bind uniformly to the drug, producing no real pattern.
5. As discussed in this module, the bottom of the hair follicle contains a bulb with cells responsible for making hair.  Higher up in the bulb, the hair is more highly organized into three layers of cells.  The middle layer, or cortex, contains keratinocytes and melanocytes.  What do these cells do?
   1. Destroy keratin and melanin
      Sorry.  Keratinocytes are cells that make keratinthey don’t destroy it.  This fibrous protein helps give the hair strength and structure.  Melanocytes, also present in the cortex, produce melanin, which gives hair its color.
   2. Destroy carotene and melatonin
      Not even close!  Carotene (beta form) gives carrots the characteristic orange color and it acts as an anti-oxidant.  Melatonin is a hormone produced in the pituitary gland that causes sleep.
   3. Make keratin and melanin
      You’re right!  Keratinocytes are cells that make keratin.  This fibrous protein helps give the hair strength and structure.  Melanocytes, also present in the cortex, produce melanin, which gives hair its color.
6. Hair color is explained in part by physics and chemistry.  The color of one’s hair is dependent upon the absorption and reflection of light (dictated by the presence of melanin).  Which hair color is the result of the most amount of reflected light?
   1. Blonde
      Hooray!  Blonde hair contains little melanin; therefore, almost all of the light is reflected.  The reflected light contains all parts of the visible color spectrum, producing the blonde or whiter color, visible to your eye.
   2. Brown
      Sorry, that’s not right.  When light hits brown hair, only some of the light is reflected; the rest is absorbed so the hair appears brown.  Blonde hair contains little melanin; therefore, almost all of the light is reflected.  The reflected light contains all parts of the visible color spectrum, producing the blonde or whiter color, visible to your eye.
   3. Black
      Sorry, that’s not right.  Black hair has a lot of melanin, so it absorbs almost all light that hits it (and your eye doesn’t detect any color).  Conversely, blonde hair contains little melanin; therefore, almost all of the light is reflected.  The reflected light contains all parts of the color visible spectrum, producing the blonde or whiter color, visible to your eye.

How did you do?