Fall2011_Lab7

=Lab 7 - Hormonal regulation of blood sugar=

Quiz on data analysis during this week.

IMPORTANT: We'll handle live mice in this class. So watch this video to prepare on how to handle them. Only one person in the group needs to handle them, so you won't have to do it if you don't want to.

Click on this link, the video is at the bottom of the web page.

Here is a [|anesthesia.pptx].

Lab procedure:
We will make a hypothesis about how the mouse regulates the amount of sugar in its blood. Mammals have the ability to secrete chemical signals that can enter the blood stream or be secreted directly to a site in the body, and these target tissues can absorb or release sugar into the blood stream. Sugar in the blood is a good thing, because it can give your body energy to breath, move, go to lab, etc. But too much can cause you to blackout, and to little can cause you to also black out.

The chemicals that are secreted are called hormones. And the organs that secret them are called hormone glands. We will work with glucagon and insulin. Diabetics take these hormones because their disease is a dysfunction of the hormone gland that secretes them. The hormone gland in this case is the pancrease. We heard about the pancrease in the digestion lab, so it's a pretty important organ that serves multiple functions. Insulin will decrease the amount of blood sugar in the blood. Glucagon will increase the amount of sugar in the blood. We won't go into the details, but these hormones don't actually DO the taking-in or releasing of sugar into the blood -- they are just signals that interact with certain tissues in the body. When these cells of these tissues interact with these hormones (the hormones pass right through the cell membrane and go into the cell), the cell changes behavior, and then the cells either take up or release sugar. Here is a cartoon about all this:

Glucagon and Insulin explained.

We can measure the blood sugar in the mouse with a blood sugar meter. These are expensive so don't play catch with them, please. I'll explain how to use them in class. We can get blood from the mouse by snipping a tiny bit (like a tenth of a centimeter) of its tail and using the drop of blood that will eventually come out. Then it will scab over and the mouse will be fine.

We can also inject the mouse with hormones and see what happens. What do you think will happen if we inject the mouse with glucagon and then wait 30 minutes and then measure the blood sugar level? And then what should happen if we inject insulin and measure the blood sugar level after 30 more minutes? Well, this is just what we will do.

1. We will get a mouse for your group. We will go over the procedure for handling the mouse, and then first anesthetizing the mouse with anesthesia. Once the mouse in sedate, it will be much easier to handle and give the other injections.

2. Read this webpage, and watch this video to get an understanding of how to handle, and how to inject the mouse. Remember how cats carry around their kittens? They grab them by the scruff of their neck, and then the kitten goes limp. Well, if you do this to the mouse, the mouse should go limp also. But you'll have to grab the skin behind the belly, also, and this will make the belly skin taunt, so the injection will be much easier to administer. Read this please: Mouse handling instructions and video.

3. We will wait until the mouse is sedate, and then we will inject the mouse with insulin. We will immediately take a blood sugar reading (snip the tail, use the blood sugar meter). This reading is the "Before" reading. Write this into your worksheet. We'll wait 30 minutes.

4. I'll talk briefly about the concept of hormones and how they work, especially the pancrease. We'll take a 15 minute quiz on data analysis. If we don't have time for the quiz, we'll take it in the next 30 minute break after the next injection.

5. We'll inject the mouse with glucagon and then immediately take a blood sugar reading. We'll then write this in the worksheet (this is the "insulin" reading) and wait 30 minutes.

We'll take the quiz if we haven't already, and we'll look at a pancrease cell, either on a slide or a picture on the projector. If we have time, we'll do some presentations.

6. We'll take a final blood reading and this will be the "glucagon" reading. We'll share all hour numbers with everyone in the class, and I'll post the final numbers here on this website.

7. Then we'll clean up and go home.

Class data:

8-10am:
 * control || insulin || glucagon ||
 * 203 || 183 || 252 ||
 * 144 || 102 || 211 ||
 * 118 || 123 || 199 ||
 * 147 || 193 || 349 ||
 * 117 || 123 || 173 ||

10-12pm:
 * control || insulin || glucagon ||
 * 99 || 65 || 149 ||
 * 96 || 67 || 82 ||
 * 137 || 106 || 185 ||
 * 137 || 132 || 225 ||
 * 58 || 130 || 310 ||

Mini-lecture (in addition to the lab procedure):
Quiz will cover the lab procedures as well; know why we had the different experimental setups: why were the different test-tubes set up the way they were with the different chemicals and stuff in each tube? What did you expect to happen in each tube, knowing what you know about digestion and enzymes and how the environment can change the behavior of enzymic reactions? What did you expect to happen with the mouse before and after the different injections and why did you think this? How did we measure the different dependent variables in the digestion and hormone lab?

Hormones.
Hormones are molecules. They can affect cells and tissues and change how these cells and tissues behave. For example, to raise or lower blood sugar, insulin and glucagon are the hormones we looked that. Somehow they are involved in raising and lowering blood sugar, but they do not directly take sugar out of the blood, nor do they put sugar into the blood. Instead, when these molecules get into muscle tissue and muscle cells (but also fat cells are affected, for example), the hormones signal the muscle cells (or fat cells) to change behavior and to begin to take in sugar from the bloodstream, or to change behavior and release sugar into the bloodstream. This way, hormones can indirectly cause different cells and tissues, all around the body, to change behavior. Sometimes the same hormone can cause different responses in different cell types (muscle vs. neuron, for example).

Types of hormone glands.
Endocrine and exocrine. The 'endo' is "inside" and the 'exo' is "outside". We've seen 'endo' before in endoderm, the innermost germ layer in di- and tripoblasts. Here, the inside or outside refers to whether the hormone travels to its destination inside or outside of the bloodstream. The pancreas is both an exo and endocrine gland. This is because it pumps out pancreatic juice into the small intestine to directly act on lipids for digestion. It also secretes insulin and glucagon into the bloodstream, where these hormones travel all throughout the body to affect different tissues in order to change the concentration of sugar in the body's bloodstream.

Cartoons and photos of pancreatic stuff:
@http://www.profimedia.si/picture/pancreas-drawing/0042198489/ @http://217.138.0.100/media/310393/enlarge

@http://www.udel.edu/biology/Wags/histopage/colorpage/cp/cpai.gif (alpha/beta cells are on the left, in the circular glob; acini are everywhere else)