Lecture 3 Flashcards
What is the RMP (resting membrane potential) value?
-70 mV
What causes the RMP?
The slight ionic balance of oppositely charged ion across the membrane -Different concentrations of ions on each side of membrane
What ion is the major determinant of RMP?
K+ as the cell membrane is more permeable to K+ than other ions
What is negative feedback?
A system that OPPOSES the CHANGE by creating a response in the opposite direction. brings variable back to the reference point.
What is positive feedback?
System that reinforces the change that is occurring. AMPLIFIES/ACCELERATES change. Variable moves further away from set point. Used when there is a specific end point
Name 2 examples of positive feedback:
Child birth & blood clots
What is feed forward?
Sytem anticipates the change in a controlled variable and makes predicted corrections
What does feed forward do?
Reduces the effect a change in environment will have on the body, before the change actually occurs.
The two types of feed forward are:
Behavioural - e.g putting a jersey on before going outside in a cold day
Physiological - e.g getting goose bumps & shivering as you enter a cold environment (core body temp has not decreased yet)
What is the controlled variable?
Variable that the system tries to keep stable e.g core body temp
What is the set point?
The target value for a controlled variable
What is the reference range?
Values of the controlled variable within acceptable limits.
What is the sensor?
Monitors the actual value of the controlled variable. If deviations occurs sensor generates a signal to the integrator
What is the integrator?
Compare actual value with set point value & determines the appropriate response
What is the effector?
Produces the response that restores the controlled variable to its ‘set point’
