Ap Biology Lab 10 - Physiology of the circulatory system

Hi. It's Mr. Andersen and welcome to AP Biology Lab 10. This is on the physiology of the circulatory system. It has two parts to it. The first thing we're going to do is we're going to measure blood pressure of us. In other words we're going to measure the blood pressure of you. And then the next thing we're going to do is we're going to measure how temperature effects the circulatory system. In this case we'll use goldfish. You could use daphnia to do this. But goldfish work great. So those are the two things we'll do in this lab. First of all let's get to the blood pressure. To measure blood pressure we use a device called a sphygmomanometer which it took me awhile to figure out how to say that. But a sphygmomanometer is essentially a cuff that has a pressure gauge on the side. And we're going to measure the pressure exerted by that cuff in millimeters of mercury. And then the other thing remember that they use to check your blood pressure is something called a stethoscope. So they're going to be listening. So you know this. In blood pressure you have two numbers. The upper is the systolic blood pressure. And the diastolic. And so how do they do that? Well basically what they'll do is they'll put the pressure cuff on your arm up here. They squeeze it until it gets really tight. They get the pressure really high. Let's say maybe 180. They then put the stethoscope in. And they're going to listen below where that cuff is. And what they'll hear once they've pumped it up is they're going to hear nothing. They won't hear any sound. But you know that they then start to lessen up the pressure inside that cuff. And as it goes down and down and down and down, eventually they'll get to a point where they'll hear a sounds that sounds like this. Whoosh. Whoosh. Whoosh. Whoosh. Those sounds are called the Korotkoff sounds. Basically what's happening is that the pressure is less enough of or it's lessened enough to the point where blood can push its way through. And so you can actually hear that. They'll then lower the pressure and the pressure and the pressure. And eventually whoosh, whoosh, whoosh will go away. Once that goes away that's going to be your lower number. Again. So the upper number is going to be when you hear it the first time. Lower number is going to be where it goes away. But both of these are ways to measure the blood pressure inside the vessels inside you. Blood pressure that's really really high is an indicator that you could have something blocking the vessels. If it's really really low could be an injury or you could be going into some form of stress. And so it's a quick way to measure the health of an individual. And it's always the first thing that they do to me when I go to into the doctor. And so what could effect that? Well if you were to stand up. That's going to increase the blood pressure in your vessels. If you were to exercise. If you're unfit, that's going to be an increase in blood pressure as well. And so all of these things that we can measure using a sphygmomanometer. But all it's measuring is the pressure within the vessels. The second thing we do is we measure the physiology of a goldfish. In this one what we're going to do is we're going to start with a goldfish at a higher temperature. Maybe 30 degrees celsius. We're then going to add ice to it. And as that ice decreases the temperature down to maybe 5 degrees celsius, we're going to measure the respiration rate of the fish. How do we do that? Well they have a thing right here called the operculum. The operculum is attached to their gills underneath it. And so basically when they breath their operculum is going to move like that. And so you can count it from the side. You can count the number of breaths that they are taking in a given period of time. So it tells us the respiration rate. And what we'll find is as we decrease the temperature, their respiration rate is going to decrease as well. And the reason why is that they are an ectotherm. In other words their temperature is derived from their surroundings. If we were to put a little mouse in here we would find different results. So what do we find for results? Basically if this is our temperature down here and this is our respiration rate, so that's breaths per minute or operculum movements per minute. We're going to find that there is a pretty direct relationship between the two. As we increase the temperature then the rate is going to increase as well. We increase it too much, obviously the fish is going to die. But there's a pretty direct relationship. If we were to do that with a human we would find that it's going to stay essentially the same. Because our rate is always going to be the same for the most part because we maintain a constant internal body temperature. And so that's the physiology of the circulatory system. And I hope that's helpful.