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Questions and Answers
What is the primary function of insulin?
What is the primary function of insulin?
Which form of insulin is processed from preproinsulin?
Which form of insulin is processed from preproinsulin?
What happens to insulin in the body shortly after it is secreted?
What happens to insulin in the body shortly after it is secreted?
What primarily stimulates insulin secretion?
What primarily stimulates insulin secretion?
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What role does the C-peptide play in relation to insulin?
What role does the C-peptide play in relation to insulin?
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What activates the tyrosine kinase associated with insulin receptors?
What activates the tyrosine kinase associated with insulin receptors?
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Which additional factor can influence insulin release aside from blood glucose levels?
Which additional factor can influence insulin release aside from blood glucose levels?
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What is one of the key effects of insulin on cells?
What is one of the key effects of insulin on cells?
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What effect does insulin have on postprandial plasma glucose levels?
What effect does insulin have on postprandial plasma glucose levels?
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Which process is stimulated by insulin in terms of energy storage?
Which process is stimulated by insulin in terms of energy storage?
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Which of the following is a physiological effect of glucagon?
Which of the following is a physiological effect of glucagon?
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What role does insulin play in relation to potassium ions (K+)?
What role does insulin play in relation to potassium ions (K+)?
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What is a primary action of glucagon in the body?
What is a primary action of glucagon in the body?
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How does insulin contribute to protein metabolism?
How does insulin contribute to protein metabolism?
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Which characteristic is associated with diabetes mellitus?
Which characteristic is associated with diabetes mellitus?
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What does glucagon primarily promote in the liver?
What does glucagon primarily promote in the liver?
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What is primarily responsible for the destruction of pancreatic beta cells in type 1 diabetes mellitus?
What is primarily responsible for the destruction of pancreatic beta cells in type 1 diabetes mellitus?
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What leads to relative glucagon excess in individuals with type 1 diabetes?
What leads to relative glucagon excess in individuals with type 1 diabetes?
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How much destruction of beta cells is typically necessary for hyperglycemia to become evident?
How much destruction of beta cells is typically necessary for hyperglycemia to become evident?
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What physiological state occurs due to the inability of cells to access glucose for energy in type 1 diabetes?
What physiological state occurs due to the inability of cells to access glucose for energy in type 1 diabetes?
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What is a direct consequence of hyperglycemia on the kidneys?
What is a direct consequence of hyperglycemia on the kidneys?
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What happens to potassium levels in the blood when insulin deficiency occurs?
What happens to potassium levels in the blood when insulin deficiency occurs?
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Which metabolic process is initiated due to the lack of insulin in type 1 diabetes?
Which metabolic process is initiated due to the lack of insulin in type 1 diabetes?
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What substance is released into the bloodstream for energy when fat is broken down in type 1 diabetes?
What substance is released into the bloodstream for energy when fat is broken down in type 1 diabetes?
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What is the indicated HbA1c level that signifies diabetes?
What is the indicated HbA1c level that signifies diabetes?
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Which test measures blood sugar after fasting for at least 8 hours?
Which test measures blood sugar after fasting for at least 8 hours?
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What characterizes Type 1A Diabetes Mellitus?
What characterizes Type 1A Diabetes Mellitus?
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Which of the following is NOT a diagnostic criterion for diabetes?
Which of the following is NOT a diagnostic criterion for diabetes?
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What type of immune response is involved in Type 1A Diabetes Mellitus?
What type of immune response is involved in Type 1A Diabetes Mellitus?
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What distinguishes Type 1B Diabetes Mellitus from Type 1A?
What distinguishes Type 1B Diabetes Mellitus from Type 1A?
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Which environmental factor is mentioned as a trigger for Type 1 diabetes?
Which environmental factor is mentioned as a trigger for Type 1 diabetes?
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Which of the following describes the beta-cell destruction in Type 1 diabetes?
Which of the following describes the beta-cell destruction in Type 1 diabetes?
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Which of the following is NOT a type of sensory deficit?
Which of the following is NOT a type of sensory deficit?
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What can lead to skin breakdown in diabetic patients?
What can lead to skin breakdown in diabetic patients?
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Which autonomic dysfunction is characterized by low blood pressure upon standing?
Which autonomic dysfunction is characterized by low blood pressure upon standing?
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How does hyperglycemia affect white blood cell function?
How does hyperglycemia affect white blood cell function?
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Which factor contributes to an increased risk of infection in individuals with diabetes?
Which factor contributes to an increased risk of infection in individuals with diabetes?
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What is a potential consequence of high blood sugar leading to the formation of advanced glycation end products (AGEs)?
What is a potential consequence of high blood sugar leading to the formation of advanced glycation end products (AGEs)?
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Which of the following describes an effect of increased capillary permeability due to AGEs?
Which of the following describes an effect of increased capillary permeability due to AGEs?
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What harmful effect can reactive oxygen species generated by AGEs have?
What harmful effect can reactive oxygen species generated by AGEs have?
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How does AGEs affect nitric oxide levels in the body?
How does AGEs affect nitric oxide levels in the body?
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What happens to glucose when blood sugar levels are very high?
What happens to glucose when blood sugar levels are very high?
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What occurs as a result of sorbitol accumulation in cells?
What occurs as a result of sorbitol accumulation in cells?
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What can excessive swelling of cells due to osmotic pressure lead to?
What can excessive swelling of cells due to osmotic pressure lead to?
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Which condition can be caused by AGEs promoting coagulation in blood vessels?
Which condition can be caused by AGEs promoting coagulation in blood vessels?
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Study Notes
Insulin Physiology
- Insulin is a hormone produced by beta cells in the islets of Langerhans.
- It regulates carbohydrate and lipid metabolism, and has a minor impact on protein metabolism.
- Insulin breaks down quickly, with a short half-life.
- Any insulin secreted into the bloodstream is cleared within 15 minutes.
Insulin Synthesis
- Preproinsulin: The initial form of insulin, a larger protein.
- Proinsulin: Preproinsulin is processed, containing three peptide chains (A, B, and C).
- Insulin: Proinsulin is further processed, removing the C peptide, leaving only the A and B peptides, forming the active form of insulin.
- C-peptide: While removed during insulin formation, the C-peptide is important for measuring insulin production and may slow complications in diabetes.
Insulin Secretion
- Stimulated by: Increased glucose levels in the blood, along with amino acids and free fatty acids.
- Inhibited by: Low glucose levels in the blood and high insulin levels. This is a feedback mechanism.
- Other stimuli: Gastrin, cholecystokinin (CCK), and other gastrointestinal hormones, along with parasympathetic nervous system stimulation also influence insulin release.
Insulin Action
- Receptors: Insulin receptors are found on cell membranes, allowing cells to receive the insulin signal.
- Structure: Receptors consist of two alpha subunits that bind to insulin and two beta subunits with tyrosine kinase activity.
- Activation Cascade: Insulin binding activates tyrosine kinase and other intracellular enzymes (e.g., PKB and MAP kinase) leading to a series of physiological effects.
- Glucose Uptake: Insulin stimulates glucose uptake into cells, bringing glucose transporter proteins (GLUT4) to the cell surface.
- Glucose Storage: Promotes glucose storage as glycogen in liver and muscles.
- Fatty Acid Synthesis: Promotes fatty acid synthesis and triglyceride formation, particularly in adipose tissue.
- Amino Acid Transport: Transports essential amino acids into cells, stimulating protein synthesis.
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Description
This quiz covers the fundamental aspects of insulin physiology, including its production, metabolism, and secretion. Learn about insulin synthesis from preproinsulin to the active form and the role of C-peptide. Test your knowledge on how insulin functions in the body and its regulation.
