Hypertension (high blood pressure) affects the whole body, so all body systems will be targeted. Here's what can happen to each system mentioned:
Circulatory: This is by far the system that's going to be the most affected by hypertension. The increase in pressure within the artery walls can cause them to blow out (embolism); it causes undue strain upon the heart and can lead to an enlarged heart and eventual heart failure; blood supply can become constricted to the extremities (hands and feet), leading to blood clots. The clots may dislodge, move through the body, and cut off blood supply to the brain, leading to a stroke; renal (kidney) failure or hemorrhaging may occur; loss of vision due to the rupturing of blood vessels because of the extreme arterial pressure.
Respiratory: Since the lungs are so dependent upon the heart and circulatory system, anything that affects the one affects both of them. Blood clots or bleeding in the lungs caused by hypertension are potential life-threatening situations.
Digestive: The digestive organs depend upon a rich blood supply to carry out their many functions. And restriction to that supply hinders their ability to get nutrients to all parts of the body. Mal-absorption, malnutrition, indigestion, constipation . . . these are just some of the problems that can occur.
Nervous: If the human body were a computer, the nervous system would be its OS (operating system). It stands to reason, then, that it's the most important system of all. Voluntary and involuntary nerve impulses keep everything in the body going. Without adequate blood supply, our nerves cannot work properly (or not at all). So, hypertension greatly affects the nervous system.
It goes without saying that hypertension is going to affect the Reproductive, Skeletal, Muscular, Endocrine, and Immune Systems as all bodily systems are interconnected, and what affects one is going to affect all.