BPM higher when sitting vs. supine?!
Question: BPM higher when sitting vs!. supine!?
I'm in college-level bio!. We had a lab on the cardiac cycle today, and did an EKG!. Values compared where when in supine position, sitting, and then inhalation/expiration!.
I am doing the post-lab and need to give a physiological reason why BPM increases when sitting rather than supine!. The reason cannot be gravity!!
Is it because when you sit, your muscles contract thus metabolizing oxygen, which means your heart must pump blood faster to make up for the oxygen deficit!?Www@Answer-Health@Com
I am doing the post-lab and need to give a physiological reason why BPM increases when sitting rather than supine!. The reason cannot be gravity!!
Is it because when you sit, your muscles contract thus metabolizing oxygen, which means your heart must pump blood faster to make up for the oxygen deficit!?Www@Answer-Health@Com
Answers:
The sitting-supine difference is due to hydrostatic pressures influence acting mainly, if not wholly, through the carotid sinus reflex!. Significant variation in the activity of this reflex may occur at different periods of the day and on different days; such variations are associated with the absence or marked occurrence of a sitting-supine difference!.
When the reflex is not active, a change from lying to supine, or vice versa, causes no change in pulse-rate; the different incidence of gravity on the splanchnic area and changes in the tension of the abdominal wall and in the tone of the back-muscles, etc!., are evidently unimportant as regards the pulse-rate, which is not affected by splanchnic adjustment, compensatory as regards blood-pressure, when the trunk is moved into the vertical position!.
The sitting-supine difference is associated with hydrostatic pressures influence acting on the altered position of the thighs, horizontal or vertical, in the two postures!. The relative position of the leg is unimportant!. In the horizontal position, prone, lateral, or supine, variation in the position of the thighs is ineffective; when the upper end of the trunk is elevated to the vertical or to a certain extent from the horizontal, certain changes in the position of the thighs affect the pulse-rate!.
The increased heart-rate in the standing position is not accounted for by gravity acting on the capacious splanchnic area, determining a lowering of aortic pressure, for a lowering does not occur in normal subjects; nor is the acceleration dependent on increased tone of the abdominal wall, trunk-muscles, etc!., nor upon the position and tension of the muscle-groups of the lower limbs!.
Www@Answer-Health@Com
When the reflex is not active, a change from lying to supine, or vice versa, causes no change in pulse-rate; the different incidence of gravity on the splanchnic area and changes in the tension of the abdominal wall and in the tone of the back-muscles, etc!., are evidently unimportant as regards the pulse-rate, which is not affected by splanchnic adjustment, compensatory as regards blood-pressure, when the trunk is moved into the vertical position!.
The sitting-supine difference is associated with hydrostatic pressures influence acting on the altered position of the thighs, horizontal or vertical, in the two postures!. The relative position of the leg is unimportant!. In the horizontal position, prone, lateral, or supine, variation in the position of the thighs is ineffective; when the upper end of the trunk is elevated to the vertical or to a certain extent from the horizontal, certain changes in the position of the thighs affect the pulse-rate!.
The increased heart-rate in the standing position is not accounted for by gravity acting on the capacious splanchnic area, determining a lowering of aortic pressure, for a lowering does not occur in normal subjects; nor is the acceleration dependent on increased tone of the abdominal wall, trunk-muscles, etc!., nor upon the position and tension of the muscle-groups of the lower limbs!.
Www@Answer-Health@Com