5.1.1 The need for Communication and Homeostasis COMPLETE Flashcards
Why communication between specialised cells is needed
To ensure correct conditions for enzymes is maintained
Defintion: Stimulus
Any change in the environment that causes a response e.g. season
Define: Response
A change in behaviour or physiology as a result of a change in the environment e.g. changing thickness of a coat/ its colour
Internal Stimuli
Example is when waste products are removed from tissue fluid after being released from metabolic processes by the blood.
Features of a good communication system
- Cover whole organism
- Rapid Communication
- Short and long term responses
- Specific Communication
Two major communication systems
- Neuronal System
- Hormonal System
Defintion: Homeostasis
Maintenance of internal environment in a constant state despite the internal and external changes
Negative Feedback
Reversal of change in the internal environment back to optimum conditions
Cell signalling
Stimulus -> Receptor -> COMMUNICATION PATHWAY -> Effector -> Response
Positive Feedback
A process that increases any change detected by the stimulus, tends to be harmful i.e. when you get cold and during labour
Definition- Ectotherm
An organism that relies on external sources of heat to regulate its body temp.
Definition- Endotherm
An organism that can use internal sources of heat to regulate/ maintain body temp. i.e. heat from metabolism
Advantages of being an ectotherm
- Use less of their food in respiration
- Need to find less food and survive longer without eating
- More of energy obtained used for growth.
Disadvantages of being an ectotherm
- They’re less active in cooler temps and may need to warm up before becoming active, greater risk of predation
- Not capable of activity during the winter so must store sufficient energy
Heat transfer
- Depends on the thermal gradient
- lost of gained via convection, conduction or radiation
- Only lost via latent heat of vaporisation
Behavioural Adaptions
INCREASE absorption- bask in sun, vibrate wings, larger SA facing sun
DECREASE absorption- Burrowing, hold body away from hot sand
Physiological Adaptions
INCREASE absorption- increased SA i.e. extra frills on lizards, changes colour
DECREASE absorption- increased abdominal movements so more water evaporates
Definition- Exergonic Reaction
A reaction that releases energy in the form of heat
Advantages of being an endotherm
- Fairly constant body temp regardless of environment
- Activity in low temps possible
- Ability to inhabit colder regions of planet
Disadvantages of being an endotherm
- Significant amount of energy intake is used to maintain temp
- More food therefore required
- Less energy for growth
Role of the hypothalamus
Monitors your bodies core temperature using the blood that flows through it, if it differs form 37 degrees it will send signals to reverse change.
Role of Peripheral Temperature Receptors
Found in the skin and send messages to hypothalamus as an early warning, i.e. walking into a cold room
