DUMMY

01. Describe how the cardiovascular system compensates when an individual goes from a supine position to a standing position.
In a normal human body always equilibrium is maintained and there are various mechanisms to maintain it. When a person changes his position, or exercise there will be various changes which will be regulated in short span of time. So the cardiovascular changes which takes place in the body when the position from supine to standing are, due to change in the gravitational force,
· There will be redistribution of venous circulation to the legs, which decreases venous return which leads to decreased right ventricular stroke volume.
· Arterial blood pressure: Arterial blood pressure decreases.
· As head becomes uppermost part of the body, cerebral blood flow is also compromised.
The changes in the arterial blood pressure are sensed by baro receptors present in the carotid sinus and aortic arch and the regulation process starts. Homeostasis is maintained in the body by various receptors, which detects the bodily changes and send signals to the controlling centres and the required action will happen.
Negative feedback loop in homeostasis
· Stimulus: In cardiovascular compensation, when a person goes from supine to standing position, the changes in heart rate, arterial blood pressure, acts as a stimulus. When there is a change in heart rate and blood pressure it stimulates the baro receptors in carotid sinus and aortic arch.
· Sensors: The changes in the arterial blood pressure are detected by the baroreceptors. When a person change a position from sitting to standing or supine to standing there will be a decreased arterial blood pressure, mean arterial pressure or pulse pressure. This is identified by baro receptors and the rate of baro receptor firing decreases. This is recognised by the solitary nucleus in the medulla oblongata in the brain.
· Control Centres: When the baro receptor firing is decreased, the medulla oblongata increases sympathetic input and in turn the heart rate in increased. The sympathetic...