HYPERTENSION

HTN is defined loosely as having diastolic BP> 80, systolic BP> 140. It depends on blood volume, cardiac output, and resistance. Drugs used to tx HTN will work on these parameters.

The medulla is where the centers for vaso-cardiovascular controls are, with mostly sympathetic innervation. From the medulla, they go to the spinal cord. Preganglionic sympathetic fibers go to paravertebral or other ganglia, then the ganglionic fibers go to the heart where they produce both increased heart rate and contractile tension, to increase the blood pressure. They also go to the kidney where they will allow a greater secretion of renin, and to the arterioles increasing resistance. So there are many ways to increase the blood pressure. At the same time we have parasympathetic fibers that can go directly to the heart, which will slow the heart.

Category: Pharmacology Notes