Homeostasis

What is homeostasis and what needs to be controlled within the body

Homeostasis is the maintenance of a constant internal environment in contrast to the external environment to protect the cells and keep metabolism rate stable

Factors that need to be controlled-

• body temperature

• pH

• Water potential

• Hormone levels

• Waste products - eg. Nitrogenous waste

What is negative feedback and explain how this is used to maintain homeostasis

It’s a change in the system to reverse a change caused by the environment

It’s starts at a set point and then an input change in system causes the receptor to detect this change and via sensory neurons send a message to the co-ordinatior to give the effector a response - usually a hormone to counteract change.

What examples are there of negative feedback

• Glucose - if levels are too high insulin converts glucose to glycogen and glucagon coverts it back to glucose if levels are too low

• temp - too low and respiration rate increases to generate energy for heat and vessels constrict to prevent loss of heat. for too high - dilate

What is positive feedback

Where the effector causes a change that doesn’t counteract but changes it more. The stimulus for this change is also affected by this effector to complete the loop