digestive and circulatory
That would be the immune system
Antibiotics are used to fight infections. without them we rely entirely on the ability of our immune system to destroy attacks on our system. The immune system is a wonderful thing, however it is not good enough in many instances to contain dangerous infections, fortunately Antibiotics are capable of destroying many pathogens (A bacterium, virus, or other microorganism that can cause disease.) that would otherwise overcome our immune system.
Infections, cancer, foreign bodies, sometimes itself.
you will die
HIV invades helper T cells, which then begin to produce HIV soon after their infected. As helper T cells die, the immune system gradually weakens and becomes overwhelmed by pathogens that it would normally detect and destroy.
Very little ... but the respiratory system would slowly heal. Never back to normal, but in 6 weeks the chronic infections would begin to clear, and in about 2 years the lungs would be about as healthy as they would ever be.
The digestive system needs other body systems to provide oxygen and fight off infections. Alone, the digestive system would simply not function and die.
The skeletal system holds the body together. Without it, we would not be able to stand upright and we would be like jelly.
Cytokines play an important role in fighting some forms of bacterial infections. The cytokines basically tell the immune system that an infection is there so that the immune system can handle it.
The nervous system, muscles, glands (endocrine system), the heart, lungs and the digestive system all work together as a whole. Without the nervous system none of this would be possible.
Fungal infections would be found in the warmer part of the US. In that warmer section the more humid part would have the most fungal infections.
Yes, this is more common on people that already have a seizure disorder such as epilepsy. Repeated infections can lower the seizure threshold. Also, antibiotics used to treat UTIs, especially fluoroquinolones, can increase seizure activity in epileptics. Fevers are sometimes present with UTIs, and fevers can also produce seizures. This is more likely in an elderly patient with diminished blood flow to the brain. If the person is unable to communicate that they are in pain due to a stroke or other reason, they also may be more likely to have a seizure.