For a project, i have to explain how coronary artery disease can affect the respiratory and digestive systems, how is it that it affects them?

CAD: CAD effects the hearts capacity to function and this can lead to lower blood flow throughout your body. Your heart and lungs need to be coordinated to appropriately oxygenate blood and when heart pump not so good this relationship compromised. That's a V/Q mismatch. Poorly oxygenated blood to stomach makes it sluggish at digestion and prone to ulcers

A few ideas: Coronary atherosclerosis proceeding to heart failure causes pulmonary edema and ischemia of the gut interfering ultimately with both doing their work. Emboli from a mural thrombus after heart attack can infarct the gut. The rest are far fetched. Figure out the prejudices of the instructor who assigned this odd project and answer accordingly.