D3.3 - homeostasis: blood glucose concentration (6i) Flashcards
What is homeostasis?
Homeostasis is maintenance of the internal environment of an organism.
- Variables are kept with preset limits despite fluctuations in external environment.
What are examples of homeostatic variables in humans?
- Body temperature
- Blood pH
- Blood glucose concentration
- Blood osmotic concentration - through action of the kidney in osmoregulation
How is homeostasis maintained?
Homeostasis is maintained using hormonal and nervous communication.
What is negative feedback?
Negative feedback returns homeostasis variables to the set point, from values above and below the set point.
Why is positive feedback not appropriate for homeostasis?
Positive feedback is not appropriate for homeostasis because it amplifies a response, moving a variable further from the initial point.
- Hormonal control of childbirth (oxytocine)
What is the role of the pancreas?
The pancreas monitors blood glucose concentration and uses negative feedback to control this level, through the release of hormones from cells in the islets of Langerhans.
What are the cells found in the pancreas?
alpha and beta cells
What hormone does alpha cells produce?
Glucagon
What hormones does beta cells produce?
Insulin
How is blood glucose regulated in the body when concentration is too high?
1) Pancreas detects high BGC and beta cells produce insulin.
2) Insulin is released into the blood and transported around the body.
3a) Insulin binds to receptors on many cells, allowing them to absorb glucose by facilitated diffusion.
3b) Liver and muscle cells also store excess glucose as glycogen granules.
4) BGC falls and returns to the optimum blood glucose concentration.
How is blood glucose regulated in the body when concentration is too low?
1) Pancreas detects low BGC and alpha cells produce glucagon.
2) Glucagon is released into the blood and transported around the body.
3) Glucagon causes liver and muscle cells to hydrolyse glycogen into glucose.
4) Glucose is released into the blood.
5) BGC rises and returns to optimum blood glucose concentration.
What is the cause of Type 1 diabetes?
An autoimmune response destroying the beta cells in the pancreas, so insufficient insulin is made.
What is a risk factor of Type 1 diabetes?
Age
What are preventative methods of Type 1 diabetes?
None
What is the treatment of Type 1 diabetes?
Blood glucose is monitored frequently and insulin is either injected or released from a pump device.
What is the cause of Type 2 diabetes?
Cells become resistant to insulin and do not respond, meaning less glucose is taken up by body cells.
What are the risk factors of Type 2 diabetes?
Sustained high sugar diet, lack of exercise, obesity.
What are preventative methods of Type 2 diabetes?
Eating a balanced diet, exercising regularly and maintaining a healthy weight.
What are treatment methods of Type 2 diabetes?
Increased exercise and weight loss to achieve a healthy weight range.
What are the risk factors of Type 2 diabetes?
Sustained high sugar diet, lack of exercise, obesity.
What are the similarities of Type 1 and Type 2 diabetes?
- People with diabetes cannot regulate their high blood glucose concentration.
- Reduced uptake of glucose from the blood, into cells, leading to accumulation in blood.
- Risk factor of family history.
- Damages the eyes, kidneys and nerves, increases risk of cardiovascular diseases and slows healing of wounds.
- Treatment includes decreased carbohydrate consumption.
