The Renin-Angiotensin pathway is crucial for the control of blood pressure. Perturbations of this pathway are involved in a large number of pathological conditions, hypertension being one of them. This SimBiology project contains a model of the Renin-Angiotensin-System as described in reference .
 Lo, A., Beh, J., Leon, H. D., Hallow, M. K., Ramakrishna, R., Rodrigo, M., & Sarkar, A. (2011). Using a Systems Biology Approach to Explore Hypotheses Underlying Clinical Diversity of the Renin Angiotensin System and the Response to Antihypertensive Therapies. (H. H. C. Kimko & C. C. Peck, Eds.) Clinical Trial Simulations, 1, 457-482.
Updated screenshot and diagram.