Communication and Homeostasis. A2 Biology F214. Why do multi cellular organisms need communication systems?.
A2 Biology F214
Organisms need to detect changes in internal environments such as temp, pH, water potential of blood , tissue fluid, level of toxins, etc as these can affect the ability of cells to function efficiently.
Enzymes, dehydration, lack of respiratory substrate, toxins inhibiting metabolism, etc.
Cells signal using hormones (the Endocrine system) that travel in the blood stream and are picked up by their target cells. The endocrine system enables long-term responses.
Monitoring Controlling Internal conditions To keep them constant (or within safe limits) Despite external changes
Can you complete this with some real life examples?
Diagram to show changes to skin surface blood vessels in warm and cold conditions.
Match the stimulus, sense and receptors in the card sort activity
Use these terms to label the diagrams you have been given.
All stimuli produce generator potentials but some don’t cause a big enough change in p.d. to reach threshold potential so no action potential is generated.
You should be able to:Describe and explain how an action potential is generated.Interpret graphs of the voltage changes taking place during the generation and transmission of an action potential.
Small stimuli don’t cause a big enough change in p.d. to generate an action potential.
(P.d. doesn’t reach generator potential.)
Transmission of Action Potentials in myelinated neurones (Saltatory conduction)
Use your new knowledge to create a script to describe and explain the following animation: