36.A 44-year-old African-American woman calls 911. When the MedAct
unit arrives they find a patient with acute shortness of breath and audible
wheezing. A physical exam reveals: pulse 115 (normal 60–100), RR 42
(normal 15–20) with signs of accessory muscle use. She is coughing up
mucus. Auscultation reveals decreased breath sounds with wheezing on
inspiration and expiration. The patient has taken her prescribed medica-
tions with no relief of symptoms prior to her 911 call. Her current medica-
tion is albuterol, a moderately selective β 2 -receptor agonist. Which of the
following is true regarding those receptors:
a. They possess a single hydrophobic transmembrane segment in the form of an
α-helix.
b. They can activate plasma membrane–bound enzymes or ion channels
c. They possess an intracellular ligand-binding domain
d. They possess intrinsic enzyme activity
e. They are arranged so that both the amino- and the carboxy-terminals are
located intracellularly
Cell Biology: Membranes 101