What does ischemia cause in the body?

Other way 'round. Ischemia is caused by inadequate blood supply, and therefore inadequate oxygen supply to a part of the body. There is reversible - the tissue recovers when blood flow is restored - and irreversible ischemia - the latter resulting in tissue death. Ischemia can potentially occur anywhere in the body.
Ischemia. Ischemia means low blood flow to an organ or leg, for example. Low blood flow results in low oxygen to that organ or structure resulting in damage. Ischemia to a leg can cause pain with activity (claudication) & muscle damage. Ischemia to the heart could result in a heart attack. Ischemia to the brain could be a stroke. Etc.
Depends. Any organ with ischemia is probably not working well and the product of that organ diminished. Heart-low cardiac output kidney failure brain stroke limb gangrene.
Definition: ischemia. The term ischemia generally suggests a reduction of the blood supply to a given area of the body such that the functionality of that part of the body is impaired. Could be from a blockage in an artery delivering blood to that part of the body, or could be from a general reduction in blood supply to deliver to that part of the body. Symptoms depend on location - heart, brain, legs, abdomen...