Communication & Homeostasis Flashcards
A good communication system
- cover the whole body
- enable cells to communicate with each other + can be specific + rapid
- enable both short and long term responses
Maintaining internal conditions of the cells
- Enviroment - bathed in tissue fluid
- tissue fluid maintained by blood - excess diffuse into blood and are excreted
- the blood concentrations measured closely
Cell signalling - The neuronal system
System of neurobes communicate across synapses
- very quick signal+ response to a quickly changing stimuli
Cell signalling - The hormonal system
- blood transports endocrine hormones to target cells around the body
- longer term responses
Homeostasis
Keeping the internal enviroment constant despite external changes
- body temperature/blood pressure/ CO2 concentration/blood glucose concentration
Negative feedback
Process that brings about a reversal in a change of conditions that has been detected, back to the normal state to be maintained
Process of negative feedback
- change away from optimun
- sensory receptors detect change
- passes through a communication system ie nervous system
- effector cells ie liver/muscles reverse the change
Positive feedback
- the response increases the original change
- dangerous ie breathing in CO, caused u to breathe in more CO
- helpful- dialation of the cervix releases oxytocin, dilates more releases more oxytocin
Ectotherm
An organism that relies on external sources of heat to regulate its body temperature
Advantages of being an ectotherm
- use less of their food in respiration
- means they have to eat less food
- greater proportion of energy can be used for growth
Disadvantages of being an ectotherm
- less active in cooler temperatures (increased risk from predators)
- may hibernate so need energy stores
Temperature regulation in ectotherms
To warm up
- bask
- some anatomical ie expanding rib cage for a larger surface area
To cool down
-hide in burrow from sun
- increase breathing rate more evaporation
Endotherms
An organism that can use internal sources of heat ie metabolic reactions to maintain its body temperature
Advantages of being an endotherm
- fairly constant internal temperature no matter what the external temperature
- activites possible no matter is winter/night
- inhabit colder parts of the world
Disadvantages if being an endotherm
- larger amount of energy intake used to maintain body temperature
- more food required
- less energy used for growth
