Answer

Abstract

The pancreas is a vital body organ for glucose regulation because it produces insulin and glucagon that play critical roles in maintaining blood glucose concentration. In this experiment, the effects of partial pancreatectomy and treatment with exogenous insulin and tolbutamide on blood as well as urinary glucose concentrations were investigated in the laboratory using a rat. The levels of glucose in the samples were determined using spectrophotometry. The results of glucose concentration in the plasma and urine were in line with the explanation of the role of the pancreas in blood glucose regulation.  It was observed that group B had the highest absorbance for both plasma and urine. Also, group B had the highest glucose concentrations in both urine and plasma. These group B rats had undergone partial pancreatectomy. Therefore, this experiment effectively demonstrated that partial pancreatectomy leads to glucose imbalance in the body with a consequent excess glucose in the blood. Thus, the conclusion opines that the pancreas is an important blood glucose regulator, and even its partial removal leads to blood glucose imbalance.

Introduction

The purpose of this experiment was to investigate the effects of partial pancreatectomy and treatment with exogenous insulin and tolbutamide on blood as well as urinary glucose concentrations. Spectrophotometry was the main method used to achieve this objective whereby the absorbance of plasma and urine were compared for four different categories of rats. The main criterion used to categorize the rats was the condition of their pancreases. The human body systems are designed to maintain homeostasis. Michael, Modell, Wright, Wenderoth, & Cliff (2015) opine that homeostasis is the ability of the body to adjust its internal environment for the maintenance of a stable equilibrium. The maintenance of homeostasis is important because cells function within a range of set parameters such as temperature, oxygen, acidity, and nutrient concentration. Homeostatic responses are regulated by both the endocrine and the nervous systems.

Blood glucose is also a parameter whose concentration is tightly regulated due to its importance in maintaining metabolism in the body and the effects of its excess. The brain relies purely on blood glucose to provide energy for neuronal electrical transmissions. The hormones that can raise blood glucose concentration include Adreno corticoids, thyroxin, growth hormone, and glucagon while insulin acts to lower the blood glucose concentration. Therefore, these hormones create equilibrium in blood glucose concentration. The normal fasting blood glucose concentration ranges between 70 mg/dL to 99 mg/dL while, after two hours of a meal, the concentration should fall below 140 mg/dL. The sources of glucose in the body include the dietary carbohydrates, reserves such as liver glycogen, and metabolic processes such as gluconeogenesis. High blood sugar level activates the beta cells in the pancreas to produce and secretes insulin into the blood circulation. Insulin leads to the production of glucose transporters such as GLUT 5 on the plasma membrane of cells, and this causes more glucose to be absorbed by the cells. Consequently, the amount of glucose circulating in the extracellular fluid in the blood reduces. Blood glucose concentrations should be tightly controlled to avoid the complications of irregular fluctuations in the blood sugar concentrations.

Table 1 below shows the blood glucose levels in non-diabetic and diabetic people:

TABLE 1: BLOOD GLUCOSE LEVELS IN NON-DIABETIC AND DIABETIC PEOPLE

This table can be used to evaluate the state of control of blood glucose level based on the blood glucose concentration measurements. It is clear from the table above that blood sugar level various before and after meal intakes. However, the normal pre-prandial blood glucose level ranges from 4.0-5.9mmol/L while the normal post-prandial blood glucose level should be below 7.8mmol/L.

Insulin is a vital blood glucose regulator. According to Sembulingam & Sembulingam (2012), insulin regulates the metabolism of lipids and carbohydrates by enhancing blood glucose absorption into adipose tissues and skeletal muscles as well inhibition of hepatic gluconeogenesis. It is evident that both excess and inadequate insulin is harmful to the human body. According to the global diabetes community (2016), diabetes is the most prevalent condition caused by insufficient blood glucose regulation. The pancreas is the major organ concerned with the regulation of blood glucose. However, control of blood sugar level involves several organs, and almost all the organs can suffer the severing effects of high blood sugar levels. For instance, the blood vessels to the brain can be damaged by persistently high blood sugar levels compromising impulse transmissions from the brain. 

Unregulated blood sugar level leads to metabolic syndrome that is associated with type 2 diabetes. Metabolic syndrome is a group of illness-related conditions such as hypertension, hyperglycemia, hypercholesterolemia, and excess fats around the waistline. These conditions occur concurrently and increase the risk of diabetes, heart disease, and stroke. Delay of developing these complications can be ensured by enhanced physical activities. Otherwise, the complications of metabolic symptoms such as type 2 diabetes set in early. Type 2 diabetes results from insulin resistance. Initially, the pancreas responds by producing and secreting more insulin. However, the pancreas wears out overtime, and the result is the circulation of excess glucose in the blood.  

In this experiment, the effects of partial removal of the pancreas were studied. Four different study subjects were used to ascertain that the conditions experienced were due to the partial pancreatectomy. Blood and urine samples were collected from these four subjects. The table 2 below summarizes the description of the subjects.

Table 2:

Based on the background explanation, it is expected that specimens from group  B will have the highest glucose concentrations because their pancreas that produces insulin for blood glucose regulation has been removed. Group D specimens might not have similar high glucose observations as B because the partial pancreatectomy has been compensated for by insulin administration.

The principle behind the methodology of the experiment is the absorbance of light based on the colorization of a solution. Glucose solutions become colorized following the oxidation of D-gluconic acid and H₂O₂. Oxygen from the hydrogen peroxide reacts with o-dianisidine giving a colored product. However, the product is further reacted with sulphuric acid to increase its stability to give adequate time for reading absorbance at 540nm. The structure of D-gluconic acid is shown below (U. S. National Library of Medicine, 2016);

Below are the chemical reactions for the experiment:

Lastly, there were safety precautions for the experiment. The Iron (III) nitrate is irritant. It was also important to handle the urine and plasma specimens from the rats carefully because rats are reservoirs for agents of infectious diseases such as plague and leprosy.

Materials

• Samples for plasmas A, B and C and Urines A, B and C.
• Spectrophotometer, deionized water, test tubes, beakers, cuvettes, water bath, and pipettes.
• Glucose Assay Reagent; Iron III nitrate in 0.1M nitric acid.
• 1mg/cm³ glucose standard solution.

Method

The following solutions were pipetted into appropriately labeled test tubes.

Another series of clearly labeled tubes for urine and plasma samples were set up, and 1 cm³ of the appropriate sample added. After that, 2 cm³ of the glucose assay reagent was added to the standing tubes. The blank tube was used to auto-zero the spectrophotometer then the results for the standard and the urine and plasma samples were read and recorded.

Results

The following tables document the absorbance obtained for each sample:

Plasma

Urine

Use the space below to explain any differences observed between the results you have obtained.

Discussion

The results matched with the expected observations when part of the pancreas is surgically removed. The variations in the observations were due to the differences in the functioning of the pancreas. Group B was the major focus of the experiment as it provided details on the effects of partial pancreatectomy. The pancreatectomy led to high blood glucose levels because the internal production of insulin was compromised. Despite the accuracy of the experiment in demystifying the effects of partial pancreatectomy, there were potential causes of errors that could have led to exaggerated glucose levels in some samples. First, the volumes involved in the experiment are very minute and human errors in making the readings could have been possible. The spectrophotometer could also be a bit defective and give inaccurate results in some cases. Lastly, calculation errors, which are indeed possible, could lead to the inaccurate conversion of the absorbance to glucose concentrations. These errors could have been prevented by making the observations and calculations more carefully and requesting the assistance of the lab technician in using the spectrophotometer.

The purpose of this experiment was to investigate the effects of partial pancreatectomy, exogenous insulin, and tolbutamide on blood glucose level regulation. The results provide a succinct overview of these effects as expected from the theoretical explanation of the importance of the pancreas in blood glucose level regulation. Therefore, the purpose of the experiment was accomplished.

Conclusion

From a comparison of the experimental results from samples A, B, C and D, it can be concluded that the pancreas is a very vital organ in the regulation of blood glucose concentration. This conclusion is affirmed by the fact that group B, which had partial pancreatectomy and without exogenous insulin compensation or stimulant for insulin production, had the highest plasma glucose concentration of 2.19 mg/cm3.