- Created by: daisy yemm
- Created on: 14-02-19 16:39
Receptors are specfic- they only detect on particular stimulus.
Receptors in the nervous system convert the energy of the stimulus into the electrical energy used by neurones. Here's how they work...
Resting potential (-70mv):
- When a nervous system receptor is in its resting state there is a difference in charge between the inside and outside of the cell.
- This inside of the cell is more negatively charged.
- This creates a voltage(potential difference) across the membrane.
- The potential difference when the cell is at rest is called its resting potential and it is generated by ion pumps and ion channels.
- When there is a stimulus, the cell membrane is excited and becomes more permeable, causing the sodium ion channel proteins to open.
- Sodium ions travel back into the cell because there is now a concentration gradient.
- This alters the potential difference - this is known as the generator potential.
- Depolarisation occurs.
- A bigger stimulus excites the membrane more, causing a bigger movement of ions and a bigger change in potential difference, so a bigger generator potential is produced.
- A generator potential can trigger an action potential if it is big enough and reaches the threshold level.
- An action potential is an electrical impulse down a neurone.
- All action potentials are the same size
- A stronger stimuli causes more action potential because there's a higher frequency
- Weak stimuli causes less action potential because there's a lower frequency
- If a stimulus is too weak it will not reach the threshold level and an action potental will not be formed.
These are mechanoreceptors- they detect mechanical…