Homeostasis | Biology for GCSE/IGCSE - Year 11 PDF Download

The Concept of Negative Feedback

• Negative Feedback Mechanism Explanation: Negative feedback occurs when conditions deviate from the ideal or set point and mechanisms act to return conditions to this set point. It operates by triggering control systems to either decrease or increase levels to maintain stability.
• Operational Process: When the level of a substance rises, control systems are activated to decrease it; conversely, when the level falls, systems are engaged to elevate it back to the set point.
• Continuous Regulation: Negative feedback mechanisms operate in a cyclical manner, continuously adjusting levels to keep them within a narrow range considered normal. This ensures stability and homeostasis in biological systems.

Blood Glucose Control

• Blood glucose levels are regulated by a feedback system that involves two crucial hormones: insulin and glucagon.
• Both insulin and glucagon, vital for controlling blood sugar levels, are manufactured in the pancreas.
• Insulin is secreted in response to elevated blood glucose levels. It triggers liver and muscle cells to convert excess glucose into glycogen for storage.
• Glucagon, on the other hand, is released when blood glucose levels drop. It prompts the liver and muscle cells to convert stored glycogen back into glucose, which is then released into the bloodstream.

Type 1 Diabetes

• Type 1 diabetes is a health condition characterized by the body's inability to regulate blood glucose levels due to the pancreas not producing sufficient insulin.
• This results in consistently elevated blood glucose levels, which can lead to various health complications.
• Treatment for Type 1 diabetes typically involves regular insulin injections to help manage blood sugar levels effectively.
• Injected insulin prompts the liver to convert glucose into glycogen, thereby reducing the concentration of glucose in the bloodstream.
• Common symptoms of Type 1 diabetes include excessive thirst, weakness, blurred vision, weight loss, and in severe cases, loss of consciousness.
• Individuals with Type 1 diabetes need to monitor their blood glucose levels regularly, adjusting their insulin doses based on factors like physical activity and diet.
• Managing blood glucose levels involves maintaining a balanced diet that avoids rapid spikes in blood sugar and engaging in physical exercise to promote glucose regulation.