5.1 Flashcards
Define cell signalling.
The way in which cells communicate with each other.
What are conditions that need to be maintained in the body?
- pH
- Temperature
- Aqueous environment for products and substrates in solution
- Free from toxins and excess inhibitors
Define stimulus.
Change in internal or external environment.
Define response.
Change in behaviour and physiology as a result of stimulus.
What makes a communication pathway good?
- Rapid communication
- Covers whole body
- Enables specific response
- Enables short/long term responses
- Enables cell to cell communication
Define effector.
Cells, tissue or organs which bring about a response.
Define homeostasis.
Maintaining constant internal environment despite changes in the internal or external environment.
Define Negative Feedback.
A mechanism which reverses a change bringing the system back to the optimum.
Define Positive Feedback.
A mechanism which increases a change moving a system further away from the optimum.
Define Sensory receptor.
Cell/sensory nerve endings which can detect a stimulus in internal or external environment and create an action potential in response.
What does homeostasis regulate?
- Body temperature
- Blood glucose concentration
- Blood salt concentration
- Blood pressure
- Carbon dioxide concentration
- Blood water potential
Explain the standard communication pathway.
Stimulus -> Receptor -> Communication pathway (cell signalling) -> effector -> response
What part of brain controls temperature?
Thermoregulatory centre in the hypothalamus.
Example of useful positive feedback?
Cervix dilates causing posterior pituitary gland to produce oxytocin which causes uterine contractions further dilating cervix producing more oxytocin. Stops when birth complete.
Define ectotherm?
An organism that relies on the external sources of heat to regulate its body temperature.