Homeostatic control systems Flashcards
Define negative feedback
Negative feedback is a control mechanism which opposes any change and brings the system back to a set point
Most control systems are negative feedback systems
What are some examples of negative feedback mechanisms?
Regulation of:
1. Body temperature
2. Arterial blood pressure
3. Blood gases (O2 & CO2)
4. Blood pH
Define positive feedback
Positive feedback is a mechanism which amplifies any change in the physiological system
What are some examples of positive feedback mechanisms?
- Uterine contractions during childbirth
- Depolarization phase of action potential
- Blood coagulation (clot formation)
Describe +ve feedback in childbirth
Stimulation of uterine cervix by baby’s head
Release of oxytocin hormone from posterior pituitary
Contraction of the uterine smooth muscle
Baby pushed more into cervix increases more oxytocin hormone release
This will continue with more uterine contraction till delivery of the baby
When baby is born, positive feedback ceases
What is local homeostatic response?
Response which occurs only in the area of the stimulus
Why are local homeostatic responses important?
Enable self-regulation
Example of local homeostatic response
Highly metabolically active cells secrete substances which dilate local blood vessels
What are the types of cellular messengers used in homeostasis?
What is the gain of a control system?
