5.1 Communication and homeostasis Flashcards
What certain conditions do living things need to maintain in their cells?
-Suitable Temperature
-pH
-An aqueous environment that can contain substrates
-No toxins
Describe a stimulus
Changes in the environment
Describe a response
An organism changing its behaviour/physiology in response to a stimuli
Why does changing external environments cause for the need of a good communcation system?
The external environment may change which puts stress on the organism. They need a good communication system in order to deal with these changes and produce a response.
How is the internal environment around cells altered?
Through the activities of cells. E.g diffusion of substances into and out of cells.
Why does changing internal environments cause for the need of a good communication system?
-Substances that are produced in the cell may be toxic and cause a build up inside the cell.
-A good communication system is needed so that a response can be produced that allows for waste removal to happen
Why is a good communication system needed for organs?
-For them to be able to work together efficiently
Define cell signalling.
A process in which one cell will release a chemical that is picked up by another cell that responds to it. (How cell’s communicate)
What are the two systems of cell signalling?
Neuronal system and Hormonal system.
What is the Neuronal system?
A network of neurones that send signals to each-other across synapse junctions. Very rapid.
What is the Hormonal system?
A system that uses blood to transport signals. Cells in endocrine system release signal into blood which is transported across body. This is slower and long-term
What is Homeostasis?
The maintenance of conditions inside body
What is the mechanism of homeostasis?
Stimulus , sensory receptors, communication pathway, effector
Define feedback:
The effect a response brings on the pathway
What is negative feedback?
The mechanisms that bring the conditions back to the optimum
Describe the steps in negative feedback.
-There is a change away from the optimum condition,
-Receptors detect this change
-Communication system informs the effector
-The effector reacts to reverse the change
-There is a return to the optimum condition
What is needed for negative feedback to work?
-The change in internal environment needs to be detected
-The change needs to be signalled to other cells
-An effect response must happen that reverses change
How is negative feedback helpful?
Helps to maintain a constant internal environment
What is positive feedback?
Where the response to a change is to increase the original change
Describe the steps in positive feedback.
-Change away from the optimum condition,
-Receptor detects change
-Communication systems inform effector
-Effector reacts to increase change
How is positive feedback helpful?
Happens in pregnancy and the stretching of cervix.
-Activity of neurones rely heavily on positive feedback
What are ectotherms?, give examples.
They rely on external sources of heat, Fluctuates with external environments. For example, Snakes and lizards.
What are endotherms?, give examples.
They control body temperature within limits, they are independent from the external environments.
For example mammals.
How do ectotherms control their body temperature if they are not warm enough?
-Move into a sunny area,
-Lie on a warm surface
-Expose a larger surface area to the sun
