What do lungs, a plant leaf, and our digestive system have in common?

blood capillaries

but my answer  i think that they all take in stuff and release something

plant- take is carbon dioxide and gives out oxygen

The lungs and respiratory system allow us to breathe. They bring oxygen into our bodies (called inspiration, or inhalation) and send carbon dioxide out (called expiration, or exhalation). This exchange of oxygen and carbon dioxide is called respiration.

Digestive system- The digestive system converts the foods we eat into their simplest forms, like glucose The broken-down food is then absorbed into the bloodstream from the small intestine and the nutrients are carried to each cell in the body.

Hope this helps!! x

answer( increase) their individual contractile activity;