Blood Flow: Ohm's and Poiseuille's Laws

Practice: Epinephrine is a hormone that binds to α1 adrenergic receptors on smooth muscle cells in the walls of blood vessels. Binding of epinephrine to α1 receptors activates an intracellular signaling cascade whose end effect is to cause contraction of the smooth muscle and, thus, constriction of the blood vessel. Which of the following correctly identifies the variable in Poiseuille’s Law that will be directly affected by epinephrine binding to α1 receptors and the resulting effect on blood flow through the affected vessels?

Practice: Erythropoietin is a hormone that causes an increase in the production and release of red blood cells from the bone marrow. Which of the following correctly identifies the variable in Poiseuille’s Law that will be directly affected by an erythropoietin-mediated increase in red blood cell volume and the resulting effect on blood flow through the affected vessels?