Blood Glucose Flashcards
How do hormones travel and where do they travel?
In the blood plasma, to target cells
Where are hormones produced?
Endocrine glands
Which hormones follow the second messenger model of action?
Adrenaline and Glucagon
Describe the second messenger model of action (with the example: adrenaline)
- The hormone adrenaline approaches the receptor site
- Adrenaline fuses to the receptor site, and in doing so activates an enzyme inside the membrane
- The activated enzyme converts ATP to cyclic AMP, which acts as a second messenger that activates other enzymes that, in turn, convert glycogen to glucose
What kind of gland is the pancreas?
BOTH endocrine and exocrine
What is the pancreas’ exocrine function?
It secretes digestive enzymes into the pancreatic duct
What is the pancreas’ endocrine function?
It secretes hormones (insulin and glucagon) directly into the blood
Where are hormones secreted from in the pancreas?
Islets of Langerhans (cluster of cells)
What do alpha cells manufacture and secrete?
Glucagon
Which cells secrete glucagon?
Alpha cells
Which hormone to beta cells manufacture and secrete?
Insulin
What type of cells secrete insulin?
Beta cells
What are the natural sources of blood glucose?
- Directly from the diet when carbohydrates are broken down
- Breakdown of glycogen (glycogenolysis)
What is Gluconeogenesis?
The production of new glucose from sources other than carbohydrates
What do beta cells detect?
A rise in blood glucose level
What does insulin bind to?
Glycoprotein receptors on cell surface of most body cells
What happens when insulin binds to the receptor? What does this result in?
- This modifies the tertiary structure of glucose carrier protein channels so that they allow more glucose into cells
- Activates enzymes that convert glucose to glycogen and fat
This results in:
- More glucose absorbed into cells
- increased respiration so more glucose is used up so more glucose is absorbed
- increased rate of conversion of glucose to glycogen (glycogenesis) in the liver and muscles
- increased conversion of glucose to fat
What do alpha cells detect?
Low blood glucose
When glucagon binds to receptors what happens?
- An enzyme is activated that converts glycogen to glucose
- There is an increase in the conversion of glycerol and amino acids into glucose (Gluconeogenesis)
Where is adrenaline produced?
The Adrenal glands (above the kidneys)
How does adrenaline raise blood glucose?
- Activates an enzyme that causes the breakdown of glycogen to glucose in the liver
- Inactivating an enzyme that synthesises glycogen from glucose
