Glucagon
Glucagon (from pancreatic alpha cells) and epinephrine (from adrenal medulla) are the primary counterregulatory hormones activated during hypoglycemia.
Glucagon
- Glucagon is a peptide hormone secreted by the alpha cells of the pancreas. It serves as an antagonist to insulin and plays a vital role in increasing blood glucose levels, particularly during fasting or starvation.
- Mobilizes fuel by promoting glycogenolysis and gluconeogenesis in the liver.
- Increases fatty acid release from adipose tissue by promoting triglyceride breakdown.
- It acts through the cAMP second messenger system.
- B. Regulation of Glucagon Glucagon secretion increases during starvation or hypoglycemia, while its levels decrease following a meal when insulin levels rise. Exercise can also stimulate glucagon secretion independently of blood glucose lev
Read this in LECTURE 6: Pancreatic and Adrenal Hormones
What our notes say
- Glucagon (from pancreatic alpha cells) and epinephrine (from adrenal medulla) are the primary counterregulatory hormones activated during hypoglycemia. (Chemical Pathology MCQs: Diabetes, Renal & Liver Disease)
- Intravenous 10 to 20% glucose or intramuscular glucagon (Endocrinology and Gastroenterology Question Bank: 12 Clinical MCQs)
- Severe hypoglycaemia in a patient who cannot swallow needs intravenous dextrose or intramuscular glucagon. (Endocrinology and Gastroenterology Question Bank: 12 Clinical MCQs)
- Y: alpha cells secrete glucagon, beta cells insulin, delta cells somatostatin, and PP cells pancreatic polypeptide (Aponeurosis — Histology Question Bank)
- Glucagonoma — glucagon → gluconeogenesis/glycogenolysis (Renal, Liver, Cardiac & Adrenal Function Tests for Year 3)
- Endocrine — secretes insulin and glucagon into the blood (CRUSH COURSE (PART 2) Clinical Chem Patho)
Study material on Glucagon
- LECTURE 6: Pancreatic and Adrenal Hormones
- Endocrine and Metabolic Pathology MCQs: Practice Questions
- Endocrine and Metabolic Pathology MCQs
- Endocrine and Metabolic Pathology MCQs for Medical Students
- CLINICAL BIOCHEMISTRY LAQs & SAQs
- Medical Physiology Pp2 Year 2
- LECTURE 1: Principles of Endocrinology
- Biochemical Endocrinology, MBMB2234: Neurochemistry
- Medical Physiology II (Paper 2)
- Integrated Tissue Metabolism -LAQs and SAQs
- Endocrine and Metabolic Pathology MCQs
Practice questions on Glucagon
Which of the following is an effect of glucagon-like peptide-1 (GLP-1)?
- Stimulates gastric acid secretion.
- Inhibits insulin release.
- Slows gastric emptying.
- Promotes glucagon secretion.
Answer: C. GLP-1 is an incretin hormone released from intestinal L cells. Its key actions include stimulating glucose-dependent insulin secretion, inhibiting glucagon secretion, and slowing gastric emptying, all of which contribute to lowering post-prandial blood glucose levels. It also inhibits gastric acid secretion.
Glucagon (in high concentrations, e.g., type 1 diabetes) facilitates all except ---
- Lipolysis
- Gluconeogenesis
- Hepatic glycogenolysis
- Muscle glycogenolysis
- Muscle glycogenolysis (Skeletal muscle lacks glucagon receptors.)
Answer: D.
The primary target for glucagon is the ---
- Liver
- Hypothalamus
- Adrenal cortex
- Pancreas
- Kidney
Answer: A.
Hormones like insulin, glucagon, and epinephrine ---
- Can only regulate key enzymes in metabolic pathways
- Can only regulate the activity of transcription factors
- Can regulate key enzymes in metabolic pathways and regulate the activity of transcription factors
- Can only regulate pathways associated with amino acid synthesis
Answer: A.
When epinephrine or glucagon binds to their receptor and activates the cAMP cascade, all happen EXCEPT ---
- GDP dissociates from G-protein and GTP associates
- Alpha-subunit activates adenylate cyclase
- G-protein is freed from its tether and diffuses away from the cell membrane
- Alpha-subunit hydrolyzes GTP and becomes inactive
- The alpha-subunit bound to GDP must reassociate with beta/gamma before binding to occupied receptor
Answer: A.