1. Communication and Homeostasis Flashcards
What is homeostasis?
Used in many living organisms to maintain conditions inside the body, despite changes in external and internal factors.
What is the standard response pathway for homeostesis
stimulus- receptor- communication pathway (cell signalling)- effector- response
What are sensory receptors?
They may be on the surface of the body or internal.
They monitor changes in the external environment or inside the body.
When they detect change they are stimulated to send a message to an effector
What are effector cells?
They bring about a response.
What is negative feedback?
A mechanism that restores the levels to their optimum level.
It is limited, if the change is too big, the effectors cannot counteract it.
What is positive feedback?
It is a response to increase the original change.
It destabilises the system and is usually harmful.
It can help to rapidly activate a process e.g. blood clotting.
It is not involved in homeostasis as it does not keep the internal environment constant.
What are endotherms?
Organisms that uses the heat from metabolic reactions to maintain a constant temperature.
What are ectotherms?
Organisms that rely on external sources of heat to maintain body temperature.
What are the requirements for a good communication system?
Covers whole body, specific, rapid when needed, has both short and long term responses.
What is cell signalling?
The ways cells communicate.
One cell will release a chemical that is detected by another cell.
The second cell will respond to the signal released by the first cell.
What are the two main systems of communication that work by cell signalling?
neuronal system
hormonal system
What is the neuronal system?
A network of neurones that signal to each other across synapse junctions.
It enables a rapid, short-term response.
What is the hormonal system?
A system that uses the blood to transport its signals.
Endocrine cells release hormones directly into the blood.
It is recognised only by specific target cells.
Enables a long-term response.
How is temperature regulated in ectotherms?
They rely on behavioral responses
If they are too cold…
move into the sun, lie on a warm surface, expose surface area to the sun.
If they are too warm…
move out of the sun, move underground, reduce surface area exposed to the sun.
What are the advantages of ectothermy?
Less of their food is used in respiration, energy released can be used for growth instead, they need to find less food, they can survive longer periods without food.
