G. An explanation of the Genetic Code: DNA is a two-stranded molecule. Each strand is a polynucleotide composed of A (adenosine), T (thymidine), C (cytidine), and G (guanosine) residues polymerized by dehydration synthesis in linear chains with specific sequences.
Note: There are more than two types of epinephrine receptors on smooth muscle cells, so epinephrine may affect smooth muscle in other tissues in other ways. (There are subtypes of alpha and subtypes of beta.) * Details of how PLC generates IP3 are on handout 12A. We will go over this later.
Both epinephrine and norepinephrine increase heart rate. During a bout of exercise, epinephrine exerts a significant vasodilatory effect on the blood vessels associated with the skeletal muscles. Corticosteroids, including cortisol, also have an effect on blood pressure. Without the presence of cortisol, the influence of epinephrine and norepinephrine upon vascular responses is minimized (Drew and Leach, 1971). Therefore, cortisol facilitates the action of the catecholamines.