Off the top of my head, you should know blood/blood clotting, digestive (esp. SI and stomach as well as main exocrine), and (possibly) renin-angiotensin system. Past that a lot of need-to-know chemicals are part of the endocrine system (hormonal).
Off the top of my head, you should know blood/blood clotting, digestive (esp. SI and stomach as well as main exocrine), and (possibly) renin-angiotensin system. Past that a lot of need-to-know chemicals are part of the endocrine system (hormonal).