Homeostasis and Thermoregulation Flashcards
What is the definition of homeostasis?
The maintenance of a stable equilibrium in the conditions inside of the body, with small fluctuations over a narrow range of conditions.
What is negative feedback?
When there is a stimulus, effectors work to reverse the change and restore conditions to their optimum level.
What is positive feedback?
When there is a stimulus, the effectors are stimulated so that it can reinforce that change and increase the response.
How does the body react to stimuli?
Stimulus - receptor - cell communication - effector - response
What is thermoregulation?
Maintaining a relatively constant core body temperature.
What causes organisms to heat up and cool down? (5)
- Exothermic chemical reactions
- Latent heat of evaporation
- Radiation
- Convection
- Conduction
What is an ectotherm? (2)
- Organisms that use their surrounding to warm their bodies.
- Core body temperature is heavily dependent on environment
What is special about ectotherms in water?
- They don’t need to thermoregulate
- High heat capacity of water means the external environment doesn’t change
What is an endotherm? (4)
- Organisms that rely on metabolic processes to warm them up
- Usually maintain stable core body temperature
- Can survive in a wide range of environments
- Need more food for energy for metabolic reactions
What are some behavioral responses that ectotherms have developed? (8)
- Basking in sun
- Orientate their bodies - max. SA exposed to sun
- Conduction - pressing bodies to hot ground or rocks
- Contract muscles and vibrate to increase cellular metabolism
- Seeking shade
- Hiding in cracks in rocks
- Digging burrows
- Minimise movement
What are some physiological responses to warming in ectotherms? (2)
- Darker skin - absorb more heat
- Alter heart rate to increase/decrease metabolic activity
How do endotherms detect change in internal environment? (2)
- Peripheral temperature receptors in the skin detect surface temperature
- Temperature receptors in the hypothalamus detect the temperature of the blood deep in the body
What is the advantage of having temperature receptors in both the skin and the hypothalamus? (3)
- Gives great sensitivity
- Allows it to respond to changes
- Pre-empt possible problems that might result in the change of the external environment
What are some behavioural responses for endotherms? (3)
- Everything for ectotherms
- Become dormant in the winter (hibernate) or summer (aestivation)
- Humans wear clothes, have houses built
What are some physiological adaptations in endotherms?
- Peripheral temperature receptors
- Thermoregulatory centres of the hypothalamus
- The skin
- Muscles
