Feeback Loops - General

Define homeostasis:

The process of keeping the environment inside the body fairly constant. It is the maintenance of a steady state (feedback model to control homeostasis) by a dynamic equillibrium in which the input and output of materials are balanced.

purpose of homeostasis

helps body be independent of external environment

how is homeostasis controlled - include a diagram

by maintenance of a steady state (feedback model to control homeostasis) by a dynamic equillibrium in which the input and output of materials are balanced.

Name the components of a feedback loop

Stimulus, Receptor, Modulator, Effector, Response, Feedback

draw a general feedback loop, explaining each component

explain what happens to glucose entering liver

• liver’s blood supply comes from the hepatic portal vein - this brings blood directly from stomach, spleen, pancreas and intestines. So has first chance to absorb nutrients from digested food.

• Processes in liver:

  • Glucose used by liver cells as an energy source

  • Glycogenesis (Glucose → glycogen) and stored in the liver

  • Glucose → fat for storage

  • Glycogen stored in muscles

  • Glucose used by cells as an energy source

  • Continues in blood to maintain BGL levels

explain how the liver regulates blood glucose levels:

(draw feeback loops fo regulating when high and regulating when low, focusing only on liver as effector)

explain tolerance limits - define + what is happening if within them vs out of them

upper and lower limits between which levels fluctuate. Within these limits the body functions normally; however, a rise above, or a fall below, means that the individuals tolerance limits have been exceeded and dysfunction will occur. 

compare positive and negative feedback