Homeostasis Flashcards
What is homeostasis?
It involves physiological control systems, to maintain the internal environment within restricted limits.
What is negative feedback?
When a stimulus triggers a response that reduces the effect of the stimulus.
What is positive feedback?
When a stimulus triggers a response that increases the effect of the stimulus.
Where is insulin made?
Made by beta cells in the Islets of Langerhans in the pancreas.
Why is insulin produced?
In response to high blood glucose levels.
How does insulin respond to high blood glucose levels?
The insulin binds to complementary receptors on the cell surface membrane of muscle and liver cells.
Once bound they stimulate the addition of more GLUT 4 glucose transport proteins into the membrane. This increases the facilitated diffusion of glucose from the blood into the cells.
The insulin also stimulates glycogenesis which is the formation of glycogen from glucose.
Where is glucagon produced?
By alpha cells in the Islets of Langerhans in the pancreas.
How does glucagon respond to low blood glucose levels?
It binds to complementary receptors on the muscle and liver cells.
It then stimulates glycogenolysis- the hydrolysis of glycogen into glucose.
It also stimulates gluconeogenesis- the formation of new glucose from amino acids and glycerol.
What is the second messenger model?
Adrenaline- works in a similar way to glucagon but targets the liver more then muscles.
It binds to complementary receptors on the cell surface membrane. This binding activates adenylate cyclase- an enzyme that catalyses the hydrolysis of ATP into cAMP (Cyclic adenosine monophosphate)
The cAMP is the second messenger
The cAMP activates an enzyme called protein kinase A which then starts the negative pathway ending with glycogenolysis.
What is type 1 diabetes and how is it treated?
Where the pancreas doesn’t produce insulin.
treated through injecting insulin
What is type 2 diabetes and how is it treated?
Where the pancreas makes insulin but the body is resistant to it. It can be controlled through diet.
Treated through injecting insulin
What is adenylate cyclase?
An enzyme that catalyses the hydrolysis of ATP into cAMP (cyclic adenosine monophosphate)
What is glycogenesis?
The formation of glycogen from glucose
What is glycogenolysis?
The hydrolysis of glycogen into glucose.
What is gluconeogenesis?
the formation of new glucose from amino acids and glycerol.
