Answer :
The effect of excessive ventilation is (b). decreased intrathoracic pressure.
How to determine the effect of excessive ventilation?
Excessive ventilation is the act of breathing too fast or too deeply, which can cause hyperventilation. Hyperventilation is a condition where the lungs expel more carbon dioxide than they produce, leading to a low level of carbon dioxide in the blood. This can cause various symptoms such as dizziness, tingling, chest pain, and anxiety.
One of the effects of excessive ventilation is that it lowers the intrathoracic pressure, which is the pressure within the chest cavity. The intrathoracic pressure is normally lower than the atmospheric pressure, creating a negative pressure that helps the lungs expand and fill with air. However, when the intrathoracic pressure becomes too low, it can impair the normal function of the heart and the blood vessels.
The heart is located within the chest cavity, and it relies on the intrathoracic pressure to help it pump blood. When the intrathoracic pressure is too low, the heart has to work harder to overcome the pressure difference and maintain the cardiac output. This can cause the heart to fatigue and reduce its efficiency. Additionally, the low intrathoracic pressure can cause the blood vessels in the chest to collapse, reducing the blood flow to the lungs and the rest of the body. This can lead to hypoxia, or low oxygen levels, in the tissues.
Therefore, excessive ventilation can have negative effects on the cardiovascular system by decreasing the intrathoracic pressure. The other options are incorrect because:
a. decresed cardiac output:
This is a possible consequence of excessive ventilation, but not a direct effect. The cardiac output is the amount of blood pumped by the heart per minute, and it depends on the heart rate and the stroke volume. The stroke volume is the amount of blood pumped by the heart per beat, and it depends on the preload, the afterload, and the contractility. The preload is the amount of blood that fills the heart before it contracts, and it depends on the venous return. The afterload is the resistance that the heart has to overcome to pump blood, and it depends on the blood pressure and the vascular tone. The contractility is the strength of the heart muscle contraction, and it depends on the oxygen supply and the nervous and hormonal stimulation. Excessive ventilation can affect the preload, the afterload, and the contractility by altering the intrathoracic pressure, the blood pH, and the sympathetic and parasympathetic activity. However, these are indirect effects that may or may not result in decreased cardiac output, depending on the individual and the severity of the hyperventilation.
c. increased perfusion pressure:
This is the opposite of what happens with excessive ventilation. The perfusion pressure is the difference between the arterial and the venous pressure, and it determines the blood flow to the tissues. The perfusion pressure is normally higher than the intrathoracic pressure, creating a positive pressure gradient that drives the blood flow. However, when the intrathoracic pressure is too low, it reduces the perfusion pressure and the blood flow. This can cause ischemia, or insufficient blood supply, to the organs.
d. increased venous return:
This is also the opposite of what happens with excessive ventilation. The venous return is the amount of blood that returns to the heart from the body, and it depends on the venous pressure, the venous tone, and the respiratory and muscular pumps. The venous pressure is the pressure within the veins, and it depends on the blood volume and the gravity. The venous tone is the degree of constriction or dilation of the veins, and it depends on the sympathetic and hormonal stimulation. The respiratory pump is the mechanism by which the intrathoracic pressure changes during breathing, creating a suction effect that helps the blood flow from the abdomen to the chest. The muscular pump is the mechanism by which the skeletal muscle contractions squeeze the veins and propel the blood toward the heart. Excessive ventilation can affect the venous return by lowering the intrathoracic pressure, reducing the respiratory pump, and causing the veins to collapse. This can reduce the preload and the cardiac output."
Read more about excessive ventilation at
https://brainly.com/question/24179454
#SPJ4
Effect of excessive ventilation decreased cardiac output.
Hence, Option A is the correct answer.
What is cardiac output?
Cardiac output (CO), is defined as the volume of blood in the heart pumps every minute, that is the mechanism by which blood circulates throughout the body, particularly supplying the brain and other crucial organs with blood flow. When we are exercising, for example, the body's want the oxygen fluctuates, and changed both the heart rate (HR) and stroke volume which affects cardiac output (SV).
As a result, a cardiovascular complicated mechanism combining the autonomic nervous system, endocrine, and paracrine signaling pathways is responsible for controlling cardiac output. Every tissue in the body depends on the heart to pump blood to it in order to survive, hence any cardiovascular failure could have a large negative impact on morbidity and mortality. Nearly 30 million Americans are affected by heart disease each year, making it the leading cause of death.
To know more about cardiovascular: brainly.com/question/27441596
#SPJ4
