IBDP Biology - Control of blood glucose

Eating and exercise changes the concentration of glucose in your blood

• All cells require a constant supply of energy to work, and so blood glucose concentration needs to be carefully monitored.  
• The concentration of glucose in the blood is normally around 

90mg per 100cm³ of blood, and is monitored by the pancreas 

• Blood glucose concentration rises after eating food containing carbohydrates Blood glucose concentration falls after exercise, because more glucose is used in respiration to release energy .
• Beta 

cells secrete insulin into the blood

• Alpha cells secrete 

glucagon into the blood

• Both are secreted by clusters of cells in the pancreas called the islets of Langerhans 

When blood glucose concentration is too high  ↗️

Insulin LOWERS blood glucose concentration 

1. Insulin binds to specific 

receptors on the cell membranes of liver cells and muscle cells. It increases the permeability of cell membranes to glucose, so cells take up more glucose. 

1. Insulin activates 

enzymes that convert excess glucose into glycogen. Cells are able to store glycogen in their cytoplasm as an energy source.This process is called glycogenesis. 

1. Insulin also 

increases the rate of respiration of glucose. The higher the rate of respiration, the greater the demand for glucose and so the greater the decrease in blood glucose concentration. 

When blood glucose concentration is too low  ↘️

Glucagon RAISES blood glucose concentration 

1. Glucagon binds to specific 

receptors on the cell membranes of liver cells 

1. Glucagon activates 
2. enzymes 
3. that 

break glycogen into glucose. This process is called glycogenolysis.This glucose is released into the blood stream,increasing the blood glucose concentration. 

1. Glucagoncan also 

promote the formation of glucosefrom non-carbohydrate sources. Glucose can be formed from fatty acids and amino acids, and this process is called gluconeogenesis.  

That is the end of this topic!

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Photo References:

1. http://www.hokto-kinoko.com/healthbenefits/the-role-of-mushrooms-in-the-promotion-of-insulin-secretion/
2. https://bio.libretexts.org/Learning_Objects/Worksheets/Book%3A_The_Biology_Corner_(Worksheets)/Anatomy_Worksheets/Feedback_Loops%3A_Glucose_and_Glucagon
3. https://www.pinterest.com/pin/687291593137256486/