QuestionSBA
QuestionChoice
Metabolic hyperaemia causes **vasodilation** of blood vessels during exercise, not vasoconstriction. The increase in waste products such as lactic acid and CO2 decreases the pH of the extracellular fluid. This causes localised vasodilation of blood vessels, to help flush out the waste products and allow more oxygen to get there to meet the demand of the muscles. The increased blood flow leads to an increase in venous return, leading to a greater cardiac output.
10023603
d
Metabolic hyperaemia causes vasoconstriction of blood vessels
QuestionChoice
Sympathetic venoconstriction decreases venous volume so increases mean systemic filling pressure. This increases the pressure gradient between veins and the heart so increases venous return to the heart, leading to a greater cardiac output.
10023600
a
Sympathetic venoconstriction
QuestionChoice
Inactive skeletal muscles **vasoconstrict**, not vasodilate during exercise. If the vessels vasodilated during exercise, the total peripheral resistance would drop, resulting in reduced blood pressure.
10023604
e
Vasodilation of inactive skeletal muscles
QuestionChoice
Muscle contraction leads to the **compression** of veins and therefore increases blood pressure. This increase in blood pressure leads to an increase in venous return, leading to a greater cardiac output.
10023601
b
Muscle contraction causing the expansion of veins
QuestionChoice
Pulmonary artery pressure **increases** during exercise. This leads to a decrease in pulmonary vascular resistance, causing alveolar vessels to open up and distend more. This respiratory muscle pump allows for an increase in venous return, leading to a greater cardiac output.
10023602
c
Pulmonary artery pressure decreases
Concept
Chapter
2693
4231
Blood flow through the heart
Topic
159
Cardiovascular physiology
17118
A 23-year-old female attends a sports and exercise medicine clinic. The doctor monitors her cardiac output as she is performing different exercises.

Which of the following causes an increase in cardiac output?
a