Homeostasis - blood glucose Flashcards
What is homeostasis?
Homeostasis is the maintenance of an internal environment within restricted limits of an organism
Importance of homeostasis
Enzymes are pH and Temperature specific
Changes to water potential = burst
Ability to adapt to a wider environment, greater survival rate
5 features of a feedback mechanism (ORCEF)
Optimum point
Receptor
Coordinator
Effective
Feedback mechanism
Negative feedback
Where a change reduces the effect of a change (blood glucose)
Positive feedback
A deviation from an optimum causes even greater deviation from normal
Mechanisms for regulating body temperature
- vasoconstriction & vasodilation
- sweating
- shivering
- movement of hair
Role of the pancreas in the control of blood glucose concentration
Made of cells that produce digestive enzymes known as Islets of Langerhans.
Different types of cells of the islets of langerhans
Alpha cells = produce glucagon
Beta cells = produce insulin
Role of the liver in regulating blood sugar
It is where insulin and glucagon take effect.
Factors effecting blood glucose concentration
Diet - glucose from carbohydrates
Glycogenolysis
Gluconeogensis
Three hormones that regulate blood glucose
Insulin - beta cells
Glucagon - alpha cells
Adrenaline - adrenal gland
How do beta cells regulate glucose concentration?
Beta cells have receptors that detect rises in blood glucose.
They respond by secreting insulin into the blood plasma
Insulin combines with glycoprotein receptors on all cells but RBC causing:
An increase in the rate of glucose absorption
Increase the respiratory rate of cells
Increase the rate of glycogenesis
How do alpha cells regulate blood glucose concentration?
Fall in glucose detected by alpha cells
Glucagon is secreted directly into the blood plasma causing:
Attachment to protein receptors on liver cell
Activation of protein kinase
Active enzymes for gluconeogensis
What is the role of adrenaline in regulating blood glucose concentration?
Attach to receptors on the cell surface membrane and change the shape of the inner protein
Adenyl cyclase is activates which converts ATP to cAMP which binds to protein kinase and activates it
Protein kinase catalyses the reaction of glycogen to glucose which moves into the blood
What is diabetes?
The inability to metabolise carbohydrate
