Which respiratory volume is excluded while calculating vital capacity?

A. Rugae: The rugae are folds in the stomach lining that expand when the stomach fills with food, increasing surface area for digestion.

B. Microvilli: Microvilli increase surface area in the small intestine, not the stomach.

C. Peritoneum: The peritoneum is a membrane surrounding the abdominal cavity, not involved in surface area expansion of the stomach.

D. Muscularis: The muscularis is the muscle layer responsible for stomach contractions but does not increase surface area.

A. Increased afterload: Increased afterload, the resistance the heart must overcome to eject blood, typically reduces stroke volume because the heart has to work harder to push blood against higher pressure.

B. Decreased heart contractility: This would reduce stroke volume, as the heart would be less effective at pumping blood.

C. Increased preload: Preload refers to the volume of blood in the ventricles at the end of diastole. An increased preload stretches the heart muscle, which typically leads to a stronger contraction and higher stroke volume.

D. Decreased blood pressure: While low blood pressure may reduce afterload, it doesn't directly increase stroke volume unless other factors are at play.