Communication and Homeostasis 0.0 / 5 ? BiologyCellular processesA2/A-levelOCR Created by: lauren.glendenningCreated on: 29-03-16 16:58 Why do living organism's cells communicate? To detect and respond to changes in the environment in order to survive 1 of 21 How do multi-cellular organisms organise and communicate to a change in the environment? By using the nervous system and endocrine systems 2 of 21 What is cell signalling? Communication between cells that allows effective co-ordination of a response. 3 of 21 What are the two forms of cell signals? Electrical and chemical. 4 of 21 How are electrical signals formed? Through neurons 5 of 21 How are chemical signals formed? Through hormones 6 of 21 Which of the two signals is a faster response? Electrical signal 7 of 21 Which of the two signals is long-term? Chemical signal 8 of 21 What is homeostasis? Maintenance of a constant internal environment despite any changes in the external environment 9 of 21 Why is homeostasis important? Organisms can only function if internal conditions are kept within a narrow range 10 of 21 Give three examples of internal conditions? Temperature, pH and blood glucose levels. 11 of 21 What is negative feedback? A process that brings about a reversal in a change in any of the internal conditions 12 of 21 Why is negative feedback important? It ensures that the optimum steady state of internal conditions can be maintained. 13 of 21 What is the process causing negative feedback to occur? Stimulus--Receptor--Co-ordinator--Effector--Response 14 of 21 What is a stimulus? A change in the environment that causes a response. 15 of 21 What is a receptor? A cell that detects a stimulus. 16 of 21 What is a co-ordinator? An organ that controls actions taken for a response. 17 of 21 What is an effector? Brings about a response (muscle/gland) 18 of 21 What is a response? A change in behaviour/physiology as a result of a change in the environment 19 of 21 What is positive feedback? A process that increases any changes detected by receptors 20 of 21 Is positive feedback a good thing? No, it tends to be harmful and doesn't lead to homeostasis 21 of 21
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