C30 - Blood Glucose and Diabetes Flashcards
What’s the pancreas?
A small organ situated behind the stomach.
It acts as both an endocrine (hormone) and exocrine (enzyme) gland.
Majority of pancreatic cells are involved in enzyme production.
However, throughout the pancreas, there are clumps known as ‘islets of Langerhans’ which produce hormones.
What hormones does the pancreas secrete?
Glucagon (produced by alpha cells)
Insulin (produced by beta cells)
These are produced at the ‘islets of Langerhans’
What are the 2 types of endocrine cells in the ‘islets of Langerhans’, in the pancreas?
Alpha cells - produce and secrete glucagon (they’re around the edge of islets).
Beta cells - produce and secrete insulin (usually distributed around the centre of islets).
What happens when blood glucose concentrations rise?
1) Beta cells in the pancreas act as receptors and detect rising glucose concentration.
2) Beta cells secrete insulin and alpha cells stop secreting glucagon.
3) Insulin binds to membrane-bound receptors on many cells, mainly muscle and liver cells.
These cells act as effectors by increasing their uptake of glucose.
4) More glucose is converted to fats or used in respiration.
Liver cells convert some glucose into glycogen which is stored.
5) Blood glucose levels are reduced.
What happens when blood glucose levels drop?
1) Alpha cells in the pancreas act as receptors and detect falling glucose concentration.
2) Beta cells stop secreting insulin and alpha cells secrete glucagon.
3) Glucagon binds to membrane-bound receptors on liver cells.
These cells act as effectors by increasing their uptake of glucose.
4) Less glucose is converted to fats or used in respiration.
More fatty acids are used in respiration instead of glucose.
5) Liver cells convert glycogen back into glucose, which is then released into the bloodstream.
6) some amino acids and fats are converted into glucose.
7) Blood glucose levels are increased.
What does insulin do?
It binds to a receptor in plasma membranes of target cells and initiates a cascade of reactions within the cell.
This causes more glucose transporter proteins to be inserted into the plasma membrane, increasing the cell’s glucose uptake.
The binding of glucose also activates enzymes that control glycogenesis and the conversion of glucose to fatty acids.
What does glucagon do?
It binds to a receptor in the plasma membrane of its target cells.
This initiates a cascade of reactions which causes enzymes involved in glycogenolysis and gluconeogenesis to be activated.
What is type 1 diabetes?
A.k.a insulin-dependent diabetes.
A type of diabetes where little or no insulin is produced.
If left untreated, they may lose consciousness or fall into a coma.
What’s glycogenesis?
The formation of glycogen
What’s glycogenolysis?
Splitting of glycogen
What’s gluconeogenesis?
Formation of new glucose
What are the risk factors and causes of type 1 diabetes?
It’s usually caused by an autoimmune response (when a person’s immune system attacks its own cells).
Antibodies are produced which destroy beta cells in the islets of Langerhans. This results in reduced production of insulin, until none is secreted.
It is hereditary. Some HLA antigen genotypes also cause it.
Environmental factors / viral infections can a,so trigger diabetes.
What is type 2 diabetes?
A type of diabetes as a result of insulin resistance.
Although less insulin is often produced, the issue is mainly a reduced sensitivity to insulin in effector cells. (a.k.a insulin independent).
Symptoms usually less severe than type 1.
What are the risk factors and causes of type 2 diabetes?
Obesity - insulin resistance is associated with high body-fat percentage and BMI
Genetics - people with a family history have increased risk
Age - risk increases with age
High blood pressure
Low birth weight
What 2 tests can be used to diagnose diabetes?
Fasting blood glucose test
Glucose tolerance test
