Question

tiny organisms that try to damage cells are called ____.
collagens
white blood cells
cartilage
pathogens

1. select all that apply.

which four body systems play a part in the workings of the immune system?
circulatory
nervous
skeletal
respiratory
integumentary
digestive
muscular

Explanation:

Pathogens are tiny organisms like bacteria, viruses, fungi etc. that can damage cells. The circulatory system transports immune - cells, the respiratory system is a first - line defense and encounters pathogens, the integumentary system (skin) is a physical barrier, and the digestive system can encounter and deal with pathogens.

Answer:

1. D. pathogens
2. circulatory

respiratory
integumentary
digestive