| Negative feedback (1) | - Homeostatic system involve receptors, communication system + effectors |
| Negative feedback (2) | - Receptors detect when a level is too high or low, info is communicated via the nervous system or hormonal system |
| Negative feedback (3) | - The effectors respond to counteract the change, bringing the level back to normal |
| Negative feedback (4) | - The mechanism restores the level back to normal |
| Negative feedback (5) | - Negative feedback keeps things around the normal level e.g. body temp is usually kept within 0.5 c above or below 37 c |
| Negative feedback (6) | - Negative feedback only works within certain limits
- If the change is too big then the effectors may not be able to counteract it
- E.g. a huge drop in temp cause by prolonged exposure to cold weather may be too large to counteract |
| Positive feedback (1) | - Some changes trigger a positive feedback mechanism, which amplifies the change |
| Positive feedback (2) | - The effectors respond to further increase the level away from the normal level |
| Positive feedback (3) | - Positive feedback is useful to rapidly activate something e.g. a blood clot
- Platelets become activated and releases a chemical, this triggers more platelets to be activated
- Platelets quickly form a blood clot at the injury site
- The process ends with - feedback, when the body detects the blood clot has been formed |
| Positive feedback (4) | - Positive feedback can also happen when a homeostatic system breaks down e.g. if ur too co,d or too hot for too long |
| Hypothermia involves posotive feedback | - It is low bod temp (below 35 c)
- It happens when the heats lost from the body quicker than it can be produced
- As the bod temp falls the brain doesn't work properly + shivering stops
- This makes the bod temp fall even more
- + feedback takes bod temperature away from normal level, it continues to decreases unless action is taken |
| How multiple negative feedback mechanisms gives more control (1) | - Homeostasis involves multiple - feedback mechanisms for each thing being controlled
- This is coz having more than 1 mechanism gives more control over changes in ur internal enviro. than just having 1 - feedback mechanism |
| How multiple negative feedback mechanisms gives more control (2) | - Having multiple - feedback mechanisms means u can actively increase or decrease a level so it returns to normal |
| How multiple negative feedback mechanisms gives more control (3) | - If u only had 1, all u could do would be turn it on or turn it off
- You'd only be able to actively change a level in 1 direction so it returns to normal |
| How multiple negative feedback mechanisms gives more control (4) | - Only 1 - feedback mechanism means a slower response and less control |
