Question 2: (10 points total) Patient Information: A patient who is otherwise fi

Question

Question 2: (10 points total)

Patient Information:

A patient who is otherwise fine (ie. no other illness symptoms) sees the doctor due to development of: weight loss, excessive urination and thirst. After testing, the patient was diagnosed with a glucagonoma- a pancreatic alpha cell tumor that is secreting high levels of glucagon in an unregulated manner.

1) In a normal post-absorptive state, what are the stimuli that cause glucagon release; and what, if any, is/are the effect(s) of glucagon on the liver, adipose tissue and muscle? How does glucagon alter the levels of various molecules (ie. glucose, fatty acids, ketone bodies

Explanation / Answer

1.a) Stimulus/Stimuli for Glucagon release: There are various stimuli that can increase the release of Glucagon such as:-

- Low blood glucose: At the low concentration of glucose i.e. hypoglycemic condition the release of glucagon increases to maintain the blood glucose level.

- Protein rich meal: After excessive uptake of proteins the release of glucagon increases to prevent hypoglycemia.

-Excessive excercise: In the condition of stress, trauma and excessive excercise the level of glucose increases so this also stimulates the release of glucagon.

b.) Glucagon causes liver to convert Glycogen into glucose when the blood glucose level decreases. This releases glucose into the bloodstream thus bringing the glucose level to normal.

c.) Glucagon has very less effect on adipose tissue. Two such effects include :

- Causes the release of fatty acids.

- Due to its lipolytic activity it activates phosphorylase in adipose tissue.

d.) Skeletal Muscles do not have receptors for glucagon therefore glucagon has no effect on skeletal muscle.

e.) It increases the level of blood glucose - by converting glycogen into glucose.

It increases the level of fatty acids by causing the release of fatty acids from adipose tissues.

It also increases the level of ketone bodies.

2) Glucagon causes release of fatty acids from adipose tissues and further causes hepatic oxidation of these fatty acids. Due to this weight lost in the patient occurs.

3.) Excess glucagon causes increase in blood sugar level. During blood filteration in kidney, glucose accumulate in the tubules which retains more of water resulting in more urine flow through tubule causing frequent urination and excessive thirst in turn.

4.) Rise in glucagon level causes the release of ketone bodies and in turn causes acid-base imbalance called ketoacidosis.

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