IBDP Biology- Insulin and glucagon

In this IBDP Biology blog post, we will look at teh emchanisms of blood sugar concentration and how hormones aid to regulate the system.

Insulin and Glucagon 

Both hormones produced and secreted by pancreas

• These regulate blood glucose levels
• When you eat glucose is absorbed into the blood stream in the capillary beds of the villi of the small intestine increasing blood glucose level
• Works by negative feedback
• In the intestinal villi, glucose travels to hepatic portal vein which takes the blood to the liver
• Hepatic portal vein is the only blood vessel that has large fluctuations in bgl
• Hepatocytes (in the liver) processes the glucose and are triggered by insulin and glucagon
• Beta cells in the pancreas sense an increase/decrease in glucose  

If BGL goes above:

• Insulin opens protein channels in cell plasma membrane; allows glucose to diffuse into cell by facilitated diffusion
• Insulin also stimulates the hepatocytes to take in glucose and convert it to glycogen; glycogen stored as granules int he cytoplasm of the hepatocyte; same thing happens in the  muscles

If BGL goes below:

• glycogen made and stored by liver is needed in the body
• alpha cells of pancreas begin to produce and secrete the hormone glucagon 
• glucagon stimulates hydrolysis of the granules of glycogen stored in hepatocytes and muscle cells; hydrolysis produces the monosaccharide glucose
• glucose enters blood 

Diabetes 

• characterized by hyperglycemia (high blood glucose)
• Cause: Type1 due to immune system destroying beta cells of the pancreas and do not produce sufficient insulin
• Type 2: caused by body cell receptors that do not respond to insulin people with untreated diabetes have sufficient glucose in their body but not in the body cells
• Treatment: Type1 controlled by injections; Type2 due to controlled diet
•  untreated: damage to the retina, blindness, kidney failure, nerve damage, risk of cardiovascular disease, poor wound healing  

That's all you need to know for the functions of insulin and glucagon!

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References:

• https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.sciencephoto.com%2Fmedia%2F729986%2Fview%2Ftype-1-and-2-diabetes-illustration&psig=AOvVaw3_sVv7g_Q-XnD6rHZbqfuY&ust=1626326474652000&source=images&cd=vfe&ved=0CAoQjRxqFwoTCPiS37Lo4fECFQAAAAAdAAAAABAD
• https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.123rf.com%2Fphoto_31016050_stock-vector-type-2-diabetes-labeled-diagram.html&psig=AOvVaw1TU2U3Z7naRgs1xTwVtQY_&ust=1626326465727000&source=images&cd=vfe&ved=0CAoQjRxqFwoTCPi_r73o4fECFQAAAAAdAAAAABAD

Drafted by Venetia (Biology)