Understanding Physiology

Have you ever wondered what causes your heart to race when you get scared? Or why your stomach growls when you're hungry? Body functions are controlled by physiology, which is defined as the science of the functions of living organisms and their parts. Studying physiology involves studying one particular aspect while keeping all other factors controlled.

Physiology presents a challenge because the human body is extremely complex, with multiple factors that interact with each other to cause a response. Integrative physiology aims to understand how everythi ng works together, from molecules to whole organs, to the entire body, and to recognize the importance of considering complexity and variability in translating research findings into the real world.

A brief history of integrative physiology involves the work of graduate student Tom Coleman, who worked with Dr. Arthur Guyton to develop a mathematical model of the human body to understand hypertension. The model demonstrated the role of the kidney in controlling blood pressure, and Coleman continued to work on the project over the next 50 years. Today, the model has over 10,000 variables and parameters, including 14 organ systems such as the cardiovascular, renal, respiratory, nervous system, and metabolism, and can simulate different pathologies such as hypertension, diabetes, obesity, and heart failure.

The model, called HUMID, has multiple applications. One of its primary uses is in education, where it helps medical students better understand disease states and appropriate treatments. For example, the simulation of "Mrs. Pale," who gets dizzy when she stands up, allows students to learn about orthostatic hypotension and treatment options.

HUMID is also used for research purposes. For instance, the model helped develop a pacemaker device that stimulates nerves to decrease blood pressure. A surgical removal of the nerves led to the discovery of a hormone that was previously not well understood, demonstrating the model's ability to analyze redundant systems and understand their interactions.

Another potential use of HUMID is in silico clinical trials. These trials create virtual patients with different genetic makeups, diets, and lifestyles to understand who would respond to a treatment and who would not. It would prevent including patients who would not benefit from a device or drug in a clinical trial. A recent simulation of 2,000 patients with hypertension using a treatment that removes the nerves from the kidney revealed the percentage of patients whose blood pressure dropped after treatment and those whose blood pressure went up.

In summary, studying physiology is essential in understanding how the human body works. HUMID, the most advanced computer simulation of human physiology, offers various applications for education, research, and clinical trials using virtual patients. The vision of Coleman and Guyton has evolved into an exciting development for the future of understanding human physiology.

Despite its benefits, there are some limitations to using computer models in physiology. HUMID has been designed to mimic the biological processes of a human body. However, it doesn't take into account factors such as age, ethnicity, or gender that can have an impact on the functioning of the body. Additionally, the mathematical models of such complex systems can be limited by uncertainties in measurements or estimates of the parameters, simplifications made to the models, and lack of data to support the assumptions made.

In conclusion, while computer modeling is a powerful tool in physiology research and education, it should not replace the real-life testing of treatments and technologies. However, HUMID's ability to create virtual patients is an exciting new development in the field of clinical trials. As technology advances and more data become available, the potential of HUMID and other computer models in physiology research and education may continue to grow.