Blood sugar control
Blood sugar is glucose. As you know, glucose is a reactant/raw material in respiration and it is very soluble.
The amount of glucose needs to be tightly controlled so that:
- cells have enough glucose for respiration
- it does not interfer with the osmotic balance of body fluids.
The normal concentration of glucose is approximately 80mg per 100ml of blood.
Glucose is mainly controlled by the pancreas, a leaf shaped organ situated in the abdomen.
The pancreas produces two hormones; Insulin and Glucagon.
But when does it do so?
- This is when blood glucose levels go below the Norm, this happens mainly after a period of fasting and when you are doing demanding exercise.
- This is when blood glucose levels go above the Norm. This happens shortly after taking sugary food/drink or later after a meal with starch has been digetsed.
When blood glucose levels rise above the Norm, the pancreas releases insulin. Insulin travels through the blood to the liver and muscles where:
- It makes the liver change excess glucose into glycogen (an insoluble sugar) which is stored
- It makes muscles respire faster, using up excess glucose
- Generally it increases the glucose uptake of most cells
****Do not confuse Glucagon ( a hormone) with Glycogen (a sugar)
When blood glucose levels fall below the Norm, the pancreas releases Glucagon, which acts in a way opposite to insulin:
- It makes the liver breakdown glycogen back to glucose which is supplied to the cells through the blood.
- It inhibits insulin production
- makes body cells take up less glucose
Sometimes problems occur with the sugar control mechanisms leading to Diabetes. There 2 types of Diabetes.
- Type1 Diabetes-
- Sometimes called Early onset diabetes or Juvenile diabetes, happens when the pancreas cannot produce insulin at all. This can happen due to auto immune diseases, where the immune system destroys the pancreas. As a result, blood sugar levels may shoot up after a meal rich in sugars and starch.
Type 1 diabetes is treated through:
- Insulin injections
- Close monitoring of blood sugar levels
- Carefull monitoring of diet- Avoiding sugary foods, eating more fibre and starchy foods (low glycemic index foods) which digest slowly hence avoid a sugar rush.
- Type 2 Diabetes-
- happens later in adulthood and happens when the pancreas can't produce enough insulin or the liver and muscle cells do not respond to the insulin.i.e. insulin resistance.
It is associated with these risk factors:
- Old age
- Poor diets
- Over consumption of carbohydrates
Treatment of type 2 diabetes involves:
- Changes in lifestyle
- Careful monitoring of diet
****Insulin injections may not help if the cells cant respond to insulin.
- The receptors are in the pancreas (a gland)
- Their target organs (effectors) are the liver and muscles
- Both insulin and glucagon are hormones made up of proteins, so the pancreas must have lots of ribosomes (protein synthesis) and mitochondria (provide energy for protein synthesis).