Learning about the effects of insulin and temperature on these live animals proved surprising and interesting
Goldfish played a prominent role in a recent Anatomy and Physiology II class for Medical Assisting students Jaheema Cole and Sabrina Chamberlin. They obtained several fish for a lab experiment, exposed the fish to a number of conditions with varied glucose levels and temperatures, and then observed their reactions.
The students performed the entire experiment over the process of one 3-hour lab. In the days and weeks leading up to this lab, they had been studying several conditions—diabetes, hyperglycemia, hypoglycemia, hypothermia, and their effects on an animal’s ability to maintain homeostasis. They also took part in a related roundtable discussion on these concepts.
Jaheema and Sabrina began by making observations and taking notes, and then wrote down hypotheses and predictions about what they would see. “We didn’t know exactly what to expect,” Sabrina says.
Observing the effects of insulin
The first experiment was related to the effects of insulin on the goldfish. They obtained 9 fish from a local pet store: 3 small, 3 medium-sized, and 3 large (about 1.5 inches long). “Part of the experiment was seeing the impact on fish of different sizes,” Sabrina says, “to see if their weight affected their reaction time.”
To prepare for the experiment, the students ensured that the fish had not eaten for 48 hours. They began by adding insulin (in liquid form, via a syringe) to each of the beakers holding the three sets of fish. “The fish took the insulin in through their gills, as they were breathing,” Jaheema said. They were interested to notice that the effects of the insulin seem to hit the larger fish more quickly.
Adding insulin to the water led the fish, over the course of about half an hour, to display signs of low blood sugar (hypoglycemia). They noticed that when they added insulin to the water, the fish began to exhibit “gapping” behavior, in which they open and close their mouths. “This was an attempt to try to absorb as much glucose and oxygen as possible, and maintain homeostasis,” Sabrina says.
As a reaction, the fish first began moving slowly, and then swam around, seemingly “trying to find ways to stay alive,” Jaheema says. Next they observed that the fish clustered together and swam side by side, in a huddle. At one point three fish in the same beaker positioned themselves so their heads were together.
The students continued to observe until the fish floated up on their sides, and then they moved them into a beaker with fresh water. Then they added sugar to that water and watched as the behavior returned to normal. “We referred to this sugar water as their ‘safe zone’,” Sabrina says, “and we were timing to see how long this process would take.”
They said the change in the fish once they were in the sugar-added water was much faster than how long it took them to respond to the insulin. “Within about 5 minutes, they were returning to normal behavior,” Jaheema says.
Creating conditions to induce hypothermia
An additional step after the insulin was to put the fish into a beaker that contained ice as well as water. The fish remained there for 3 to 4 minutes before the students moved them to a beaker with added sugar. One of the fish, named “Freckles” because of a brown speck on its forehead, got aggressive in the cold water. They suspect Freckles was under hypothermia shock.
The students were interested to see that the ice water bath had a faster effect on the fish than the insulin did. “This was a chance to see them respond to conditions of hypothermia,” Sabrina says.
She also says they were surprised about the role that size played in the reactions. “The medium-sized fish seem to be the strongest in terms of recovery,” Jaheema says. They had predicted that the smallest—and therefore youngest—fish might do the best, since they would have strong immune systems, but their observations did not support this hypothesis.
They learned that hypoglycemia can be fatal in a relatively short amount of time. “Hyperglycemia—too much blood sugar—can be fatal, too, but it will take much longer for the effects to set in,” Jaheema says. They were glad to see that all of the fish lived for at least 24 hours after the experiment was finished. “They were warriors,” she adds. “None of them died in the process of what we were putting them through.”
“I enjoyed the experience, and I learned a lot,” Jaheema says. “I appreciate that Dr. Wong gave us the opportunity to do the experiment.” For his part, Dr. Wong is glad his students have the chance to understand more about people who suffer from conditions such as diabetes, given that it is a growing condition in the population. He likes that students can take this knowledge and apply it to how they care for friends and family members—as well as patients they will encounter in their work as Medical Assistants.
“It was good to put together all the pieces of the puzzle that we had been studying with these hands-on activities,” says Sabrina. “The active learning is definitely one of the fun aspects of this program.”
This post is part of the Salter College weekly blog. We’re committed to supporting the professional growth of all our students. Contact us today to learn more about our various career training programs, or to request more information. Call our West Boylston campus at (774) 261-1500 to schedule a visit.