Homeostasis Flashcards
What are the components of a feedback system?
- Regulated factor/ controlled variable
- detector/ sensor
- comparator/ control centre
- effector
- response
What does the effector component in a feedback system do?
Returns variable to a set point
What are the two types of comparator/ control centre in a feedback system?
Intrinsic or extrinsic
What does the extrinsic comparator do in a feedback system?
Endocrine system, nervous system
What does the intrinsic comparator do in a feedback system?
Local- cell or tissue autoregulates
Why does the value of a controlled variable oscillate around a set point?
Time delay between sensing a change and its correction
What are the two groups of regulated factors?
Physical entities and circulating concentrations of chemical substances
What are some examples of physical entities that are controlled variables?
Blood pressure and core temperature
What are some examples of circulating concentrations of chemical substances that are controlled variables?
Ions (Na+, Ca2+)
Nutrients (blood glucose conc)
Hormones
How does the body increase body temperature?
Shivering, vasoconstriction, increased metabolism
How does the body decrease body temperature?
Vasodilation, sweating
What happens to the core body temperature when there is an infection?
The set point is changed and so the body temperature rises
What are the benefits of an increase in body temperature?
- Inhibition of bacterial growth
- speed up metabolic reactions
- increased delivery of white blood cells to infection sites
How is the body temperature increased?
Blood flow is shifted to the core to conserve heat, muscle activity is increased (shivering)
When do chills stop?
When a high temperature is reached
