Homeostasis. The biological definition of homeostasis is âthe tendency of an organism or cell to regulate its internal environment and maintain equilibrium, usually by a system of feedback controls, so as to stabilize health and functioningâ.ositive feedback mechanisms. A positive feedback mechanism is the exact opposite of a negative feedback mechanism. With negative feedback, the output reduces the original effect of the stimulus.
Bacteria produce disease in one of two general ways; some bacteria damage the cells and tissues of the infected organism directly by breaking down the cells for food, other bacteria release toxins (poisons) that travel throughout the body interfering with the normal activity of the host. Pathogens.
Causes. Infectious diseases can be caused by: Bacteria. These one-cell organisms are responsible for illnesses such as strep throat, urinary tract infections and tuberculosis. Viruses. Even smaller than bacteria, viruses cause a multitude of diseases â ranging from the common cold to AIDS. Fungi. Many skin diseases, such as ringworm and athlete's foot, are caused by fungi. Other types of fungi can infect your lungs or nervous system. Parasites. Malaria is caused by a tiny parasite that is transmitted by a mosquito bite.