13.1 Coordination Flashcards
What are examples of changes in an internal environment?
Blood glucose concentration, Internal temperature, Water potential, Cell pH
What are examples of changes in an external environment?
Humidity, External Temperature, Light Intensity, New or Sudden Sound
Definition of a stimulus
A change in internal or external environment
What do receptors do?
Detect a stimulus
What are receptors?
Some are cells, proteins
What are effectors?
Cells that bring about a response to a stimulus, to produce an effect
What do effectors include?
Muscle cells, Cells found in glands
Why does cell signalling occur?
To produce a response, receptors need to communicate with effectors and effectors may need to communicate with other cells. Occurs between adjacent (eg. nerve cells at synapses, muscle cells) or distant cells (eg. hormones)
What is the purpose of cell-surface receptors?
Allow cells to recognise the chemicals involved in cell signalling
Definition of homeostasis
The maintenance of a stable equilibrium in the conditions inside the body
How do homeostatic systems detect a change and respond?
-Receptors detect when a level is too high or too low
-The information is communicated by nervous or hormonal system to effectors
-The effectors respond to counteract a change, bringing it back to normal
-This mechanism is called negative feedback
How can positive feedback mechanisms amplify a change from the normal level?
-Effectors respond to further increase the level from normal level
-Positive feedback is used to rapidly activate something
eg. platelets activated to clot blood after injury
Is positive feedback involved in homeostasis?
No, because it doesn’t keep your internal environment constant
