homeostasis
- Created by: danni :)
- Created on: 27-12-12 20:46
View mindmap
- homeostasis
- positive feedback: does NOT play a part in homeostasis as it moves parameter away from norm.
- e.g., if a person breaths in highly carbonated air, CO2 receptors register this and breathin rate increases causes even more CO2 to be breathed in.
- negative feedback e.g., core body temp. receptor detects if the temp is within a suitable range, if not, communicates with effector that causes an action to return temp to normal
- temp involves nervous and hormonal systems--> short time delay between detection, communication and action, results in oscillation around a set value.
- nervous system= short term, rapid changes.
- hormonal system= slow but more long term changes
- temp involves nervous and hormonal systems--> short time delay between detection, communication and action, results in oscillation around a set value.
- factors affecting the activities of a cell
- Temperature: low temp= metabolic reactions slow down; high temp= proteins denature & damage enzymes + cell mbs
- amount of water: lack of water in tissue fluid --> water moves out of cell by osmosis--> metabolic reactions slow/ stop ; too much water in tissue fluid --> water moves into cell via osmosis --> cells swell/ burst
- [glucose] : lack --> respiration slows/ halts= no energy ; too much in tissue fluid--> water moves out of cell metabolic reactions slow/ stop
- to control internal conditions to maintain a stable internal environment
- temperature regulation
- endotherms
- temperature receptors: the hypothalamus continually monitors the temperature of the blood flowing through it. Peripheral receptors detect change in external temperature and provide a warning that the internal temperature might change
- Can maintain their body temps.
- advantages 1) fairly constant internal temp 2) activity possible when external temp is low 3)ability to inhabit cooler parts of the earth
- disadvantages 1) significant part of energy intake used to maintain temp 2) More food required 3) less energy used for growth or more is needed to grow
- ectotherms
- Advantages 1) use less food for respiration 2) can survive longer without food 3) can use more energy from food for growth
- disadvantages 1) less active during cooler times so at risk of predation. 2) may not be capable of activity during winter, meaning they need sufficient energy stores to last
- relies on external sources to regulate its body temperature
- water has a high latent heat of vaporisation which is why , when we sweat we cool down because the water evaporates, taking heat energy with it.
- ectotherms (e.g., reptiles) cant control their temperature physiologically , so use behaviour mechanisms, such as laying in the sun to warm up, to control their body temperatures.
- endotherms
- positive feedback: does NOT play a part in homeostasis as it moves parameter away from norm.
Comments
No comments have yet been made