Given that there is a baroreceptor reflex to regulate blood pressure, how is it possible for blood pressure to remain high in individuals diagnosed with chronic hypertension?

In chronic hypertension the baroreceptors get used to high blood pressure and does not respond effeciently.

Explanation:

Hypertension is the condition when blood pressure usually remains higher than normal. The systolic higher blood pressure is considered high above from 139 (mmHg) and diastolic is considered as above from 89 (mmHg).

The condition is considered to be chronic when it affects vital organs such as lung and hurt. There are several stimuli to which brain response to maintain normal blood pressure. Most important and fast of these is baroreceptors present in blood vessels that detect the change in blood pressure and signal to brain for proper response such as dilating the blood vessels in case of high blood pressure.

In coronary hypertension the walls of blood vessels become stiffer due to several factors such as smoking, stress and ageing. The high blood pressure produces tension in the wall of artery which is detected by baroreceptor. In coronary hypertension these barorecepetors get used to higher blood pressure thus does not response to it properly. So blood pressure remains high.

The baroreceptors are no longer responding to the stretch reflex and tension   stimulus generated by the increased blood pressure on the walls of the atrial and the heart.Thus they are no longer sensitive to their own responses.

Explanation:

Groups of special receptors in the heart and blood vessels, which are sensitive to fluctuations in blood pressure, and mediate the rise and fall in the blood pressure to relatively constant levels  are called baroeceptors.

Thus an elevation in blood pressure, activated the baroreceptors in the blood vessels. With a fraction of a second, of the stimulus of tension on the walls,the receptors send   negative feed back loop of sensory signal to the control center in the medulla of the  brain.

The brain responded with motor outputs  which decreases the heart rates, vasodilation  with corresponding reduction in blood pressure; since the pressure of the blood been pumped by the heart has dropped. Conversely, a drop in blood  pressure, stimulated less activation of the baroreceptors, and therefore elevation of heart rate with consequent rise in blood pressure to relatively constant level.

Therefore, in chronic hypertension patient the reason for the blood pressure to remain high, despite  baroreceptiors is the adpatation of the baroreceptors to the elevated blood pressure. The baroreceptors are no longer responding to the stretch reflex and tension   stimulus generated by the increased blood pressure on the walls of the atrial and the heart.Thus they are no longer sensitive to their own responses

it will increase due to the time span