Introduction to Physiology

00:00 Here we are going to talk about physiology and its general principles. Now you may be thinking at this point, well, what exactly is physiology. So let's address that first. Physiology is the science of life. Physiology is fairly broad in nature and it aims to understand the mechanisms of living and this incurs all the way from the genetic and molecular to the cell and to cell function and eventually into integrated behavior of the whole body. The other thing that's important to think about with physiology is it is how the body works under normal conditions.

00:41 Why this is important is later we're going to differentiate between normal physiology and medical physiology. Physiology is used in almost everything you do in daily life from whether you're walking or exercising, whether you're reading or whether you're watching this particular Lecturio lecture. It's done in just about everything. So let's also now define what is medical physiology and difference from regular physiology. In medical physiology, one of the quotes that I like best is done by an investigative team that first discovered what an arterial blood gas is and in this case they decided that critical care medicine is basically applying physiological principles to the care of the seriously ill patient. So in medical physiology, we will talk about some topics in greater detail and drill those down because they are more medically relevant. There are some topics in physiology, however, we will just explain the concept so you understand how this works but we won't drill it down in the same way because it's less medically important. Okay, now let's bring these topics together and go through which are the various areas or systems that we need to discuss. General physiology will be those things that undergo through all organ systems in the body. The nervous system will be the brain, the spinal cord and the nerves and these help control and regulate the other organ systems and those other organ systems include the musculoskeletal system. So in terms of the muscular system this would be the contractions of muscles, how they pull on skeletal levers so that you can ambulate, walk, do the various activities of normal daily living. However, to do normal activities you need to have metabolism. For metabolism, we need to have oxygen and that's where the respiratory system comes into play. Here, the respiratory system exchanges air between the environment and into the body and to the lungs, you will be able to then absorb oxygen and you will be able to eliminate CO2. How you get that oxygen around to all the cells in the body involves the cardiovascular system. So here, we will have the heart pumping blood. Now as it pumps blood throughout the body you need to have a vasculature or a tube system so it delivers blood throughout the whole body and every cell is in close enough diffusional distance to receive that oxygen. The renal system is very important in undergoing filtration of the blood.

03:31 So like the respiratory system was adding substances, the renal system will be removing metabolic excesses or substrates. The GI system is nice in that it adds back various nutrients as needed for the cells in the body such as glucose. Finally, the endocrine system will be another one of those control in regulation systems similar to the nervous system that help us integrate all the various organ systems in the body. So now let's discuss these organ systems and how they relate to each other in more of a flow diagram. Here you can see the body is set up in a number of different layers. The top layer we have here is the lungs and this is of course where the carbon dioxide will leave and oxygen will enter. Notice that the heart is split into two, the right side of the heart pumping blood in to the lungs, we have the left side of the heart moving that blood throughout the system. The renal system will be on the third rung and that's again our filtration system. On the second rung we have the gastrointestinal system and that will be once again the spot in which blood will come to pick up nutrients like glucose, proteins, fats so that then can be delivered to all the cells of the body. Finally at the lowest rung we have the capillary beds and that is to denote all the different cells in the body and how each one of them will receive this blood that has oxygen in it, has nutrients in it and is well filtered and so that can correspond to do the normal activities that are needed for that system, whether it be the nervous system, the musculoskeletal system or the endocrine system.