Homeostasis Flashcards
What is homeostasis?
-the ability to maintain stable internal conditions within certain limits despite constant changes
What happens if there is a homeostatic imbalance?
-disease
Eg. Temperature
- normal: 37 degrees celsius
- certain limits: 36.5-37.5
- constant changes: exercise, sleep, illness, drinks
Eg. Blood pressure
- normal: 120/80 mmHg
- certain limits: 95/60-139-89
- constant change: stress, exercise, salt intake
Eg. Heart rate
- normal: 72 bpm
- certain limits: 60-100 bpm
- constant changes: exercise, sleep, anxiety, caffeine
What are the 3 parts of homeostatic control mechanisms?
1) receptor
2) control centres
3) effector
What is the role of the receptor?
-senses change or stimulus eg. nerve endings, sense organs
What is the role of the control centre?
- determines set point
- analyses input, determines response
- eg, brain
What is the role of the effector?
- cells or organ that responds
- the part of the body that does the action, not the action itself
What is negative feedback?
- the most common feedback
- stabilizes mechanisms
- effector opposed stimulus to minimize change
- returns conditions to set points
What is an example of negative feedback?
-regulation of body temp, glucose levels
What is positive feedback?
- less common than negative feedback
- amplifies stimulus to cause rapid change
- can be problematic (uncontrolled fever)
What are examples of positive feedback?
- blood clotting
- oxytocin hormones intensify labour contractions until birth
What words would you use to describe the role of negative feedback?
-when a problem is detected, it reverses it (eg. like a thermostat)
What words would you use to describe the role of positive feedback mechanisms?
-body process continues until finished (eg. childbirth) Increase stimulus (frequency, intensity)
