Blood Pressure and Regulation MCQs

Definition of baroreflex: "Whenever blood pressure Increases, baroreceptors increase their discharge and send their impulse to medulla which ultimately decreases the blood pressure Baroreflex is a classic example of Negative feedback Mechanism Even at rest, baroreceptors fire at low level. They increase their firing whenever BP increases and decrease their firing whenever BP decreases Reference: Ganong's Review of Medical Physiology 25 th edition, ch-32, page no.587

Mechanism of peripheral chemoreceptor stimulation Whenever there is low Po 2 (hypoxia), O2-sensitive K + channels in glomus cells close Accumulation of K + inside the glomus cells leads to a state of depolarization Such depolarization open calcium channels leading to calcium influx Influx of calcium causes release of the neurotransmitter dopamine which stimulates the afferent nerve endings Reference: Ganong, 25th edition page no.658

Feed forward control is also called anticipatory control Here body anticipates the change and employ corrective measures accordingly When the temperature in skin falls, hypothalamus anticipates core internal body temperature is going to fall and send impulses to prevent core temperature from falling Shivering is one important mechanism to generate heat when exposed to cold environment Reference: UMP, 4th edition RL Bijlani page no. 12

In congestive heart failure, left ventricular dysfunction increases left ventricular end-diastolic pressure, which raises left atrial pressure, pulmonary venous pressure and pulmonary capillary pressure, which is the hydrostatic pressure tending to drive fluid movement out of the pulmonary capillaries, according to Starling's law. Thus, pulmonary edema, generally limited to the interstitium of the lungs, is a hallmark of congestive heart failure. All of the other responses would act to decrease fluid movement out of the capillary, in accordance with Starling's law. Reference: Ganong, pp 592-594, 662. Kasper et al., p 204. Levitzky, pp 107-110. Stead et al., pp 25-26.

BP measured by sphygmomanometer is higher than the intra arterial pressure because the cuff pressure gets dissipated between the cuff and the artery by the interspersed tissue Reference : Ganong's Review of Medical Physiology, 25th Edition, Page Number-577.

Angiotensinogen is secreted by liver Reference: Ganong, 25th edition page no.696

Angiotensin converting enzyme is present in pulmonary capillary endothelium. It converts Angiotensin I to Angiotensin II Reference: Ganong, 25th edition page no.696

Mean Pulmonary capillary wedge pressure (PCWP) = 9mmHg (Range 4 to 12 mm Hg) PCWP is usually measured using a balloon-tipped, multi- lumen catheter called Swan-Ganz catheter Reference: Ganong, 25th edition page no.574