Regulating Blood Glucose Flashcards
What is the normal blood glucose concentration?
Between 4 and 6 mmol dm-3
What is hypoglycaemic?
When the blood glucose concentration is able to drop to below 4 mmol dm-3 and remain too low for long periods of time.
What is the main problem caused by hypoglycaemia?
An inadequate delivery of glucose to the body tissues and, in particular, to the brain.
Mild = tiredness and irratibility
Severe = Imapirement of brain function and confusion, which may lead on to seizures, unconsciousness and even death.
What is it called if blood glucose concentration is able to rise too high for long periods of time?
Hyperglycaemia.
What can permanent hyperglycaemia lead to?
Significant organ damage. A blood glucose level that is consistently higher than 7mmol dm-3 is diagnosed with diabetes mellitus.
Which cells detect a high level of blood glucose concentration?
The beta cells in the islets of Langerhans.
What are the target cells of insulin?
The liver cells, muscle cells and some other body cells including those in the brain.
What enzyme is activated as a result of insulin binding to the receptor of target cells?
Tyrosine kinase
What does tyrosine kinase cause?
It causes phosphorylation of inactive enzymes in the cell. This activates the enzymes leading to a cascade of enzyme controlled reactions inside the cell.
What are the several effects that insulin has inside the cell?
More transporter proteins specific to glucose are placed into the cell surface membrane. This is achieved by causing vesicles containing these transporter proteins to fuse with the membrane.
More glucose enters the cell.
Glucose in the cell is converted to glycogen for storage (glycogenesis).
More glucose is converted to fats.
More glucose is used in respiration.
What happens if blood glucose concentration drops too low?
It is detected by the alpha cells in the islets of Langerhans. The alpha cells then secrete the hormone glucagon into the body.
What are the target cells of glucagon?
Hepatocytes.
What happens as a result of glucagon binding to the receptors of the hepatocytes?
It stimulates a G protein inside the membrane.
What does the G protein cause?
It activates the adenyl cyclase in each cell.
What does the adenyl cyclase do?
Converts ATP to cAMP, which activates a series of enzyme-controlled reactions in the cell.
