Homeostasis - glucose Flashcards
How do hormones travel from gland to the target organ?
In blood plasma
Name the target organ for insulin and glucagon
Liver and muscles
Define homeostasis
Maintaining a constant internal environment within restricted limits.
Why is a stable blood pH essential?
Maintain conditions needed for enzyme activity
Enzymes denatured by high or low pH
Why is a stable core temperature essential?
Maintain conditions needed for enzyme activity
High temperature - denatures proteins
Low temperature - reduces rate of reactions
Why is maintaining a stable blood glucose concentration essential?
Provide a respiratory substrate for all cells
Provide a suitable water potential to prevent osmosis causing damage (shrinking/bursting) to cells
Describe the role of insulin in maintaining a stable blood glucose concentration
Reduces the blood glucose concentration
Insulin binds to receptors on target cell membrane
Causes the inclusion of channel proteins into target cell membrane
Increases rate of diffusion of glucose into target cells
Activates enzymes catalysing the conversion of glucose to glycogen
Describe the role of glucagon in maintaining a stable blood glucose cocntration
Increases the blood glucose concentration
Glucagon binds to receptors on target cell membrane
Activates enzymes catalysing the conversion of glycogen to glucose
Glucose diffuses out of cell and into blood plasma
Describe the second messenger model for glucagon and adtrenaline activity
Hormone bind to receptor on target cell
Change in tertiary structure activates adenyl cyclase
Catalyses the conversion of ATP to cAMP
cAMP activates protein kinase
Protein kinase catalyses the conversion of glycogen into glucose
Glucose passes into blood plasma by facilitated diffusion
Where is insulin made?
Pancreas
Beta cells of the islets of Langerhans
Where is glucagon made?
Pancreas
Alpha cells of the islets of Langerhans
Where is adrenaline made?
Adrenal glands
What causes Type 1 diabetes?
Pancreas releases no/insufficient insulin
Autoimmune response destroying beta cells of Islet of Langerhans
What causes Type 2 diabetes?
Receptors on target cells damaged or become less responsive to glucose
Risk factors poor diet and obesity
How is type 1 diabetes controlled?
Injection of insulin
