Module 5: Communication And Homeostasis Flashcards
Why do plants and animals need communication systems?
Plants and animals need communication systems in order to respond to both internal and external environments and coordinate the activities of organs.
What is the importance of organisms being able to respond to their internal environment?
1) Some waste products of metabolic activities are harmful- Their build up could be toxic- They act as a stimulus for their own removal.
2) Maintains constant internal conditions (homeostasis)
What is the importance of organisms being able to respond to their external environment?
1) To be able to adjust internal environment in response to external environment. E.g. temperature.
2) To adapt to changes in the environment. E.g. Weather.
3) Find resources. E.g. Tropism
Coordinating the activities of organs
Receptors and effectors may not be next to each other in the body. This means they must communicate specific messages across the whole body quickly over both short and longer term periods.
Cell signalling is how the cells communicate with one another.
What is cell signalling?
Communication between cells to help them work
together to co‐ordinate their actions.
Cell signalling is how the cells communicate with one another.
Two types of cell signalling
Neuronal systems ‐ neurones signal to each other across synapses.
Hormonal systems ‐ hormones are transported in the blood to specific target cells.
Compare the way the two cell signalling systems act
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Homeostasis
The maintenance of the internal environment in a
constant state despite internal and external changes.
Positive feedback
A process that increases any change detected by the receptors, taking the conditions further from the optimum set point. (Tends to be harmful and does not lead to homeostasis).
Negative feedback
A process that brings about a reversal of any change in conditions in order to return to an optimum set point- Essential for homeostasis.
How does homeostasis take place?
Receptor detects stimulus ‐‐> cell signalling ‐‐> effector brings about response
Explain what homeostasis is and why it is necessary and how it is maintained (5).
Homeostasis is the maintenance of the internal environment in a constant state despite internal and external changes.
It is vital to keep conditions such as body temperature, blood glucose conc. and blood pressure the same.
It is maintained through cell signalling to cause negative feedback.
For each of the examples below, state if it is an example of positive or negative feedback.
- During childbirth ‐ as the cervix stretches, oxytocin is released which increases contractions and increases cervical stretching.
- Milk production ‐ as long as baby is nursing, milk will be produced.
- High concentration of CO2 in blood leads to increase in heart rate and breathing rate.
Receptor
A cell that detects a stimulus and creates action potentials (nervous impulse).
Effector
A cell, tissue or organ that brings about a response.
