In Jainism, karma is bound mainly through intentional activity of the soul with mind, speech, and body, especially when it is accompanied by passions like anger, pride, deceit, and greed.

So:

• Heartbeat, breathing, digestion: these are natural bodily functions and do not create karma by themselves in the same way deliberate actions do.
• Walking and speaking: these can create karma if done with carelessness, attachment, violence, or passion.
• Automatic or unconscious movements: the physical movement alone is not the main cause; the inner state is what matters most.

In Jain teaching, karma is bound through yoga (activity of body, speech, and mind) together with kasāya (passions). Without passion, the bondage is much less.

So the simple answer is:

Automatic bodily functions do not normally create new karma in the same way intentional, passionate actions do. But careless living, harmful movement, or speech can still bind karma if there is violence or passion involved.

If you want, I can also explain this in terms of dravya karma, bhava karma, and pudgala in simple Jain language.