1. - The central nervous system consists of the brain and the spinal cord - sensory information is received by them and interpreted and then processed (responded to) - motor neurons carry the response from the CNS to an effector (a muscle or gland) 6.5.1 State that the nervous system consists of the central nervous system, (CNS) and peripheral nerves, and is composed of cells called neurons that can carry rapid electrical impulses

2. 6.5.2 Draw and label the structure of a motor neuron

3. - Neurons are the specialized cells of the nervous system - Sensory neurons carry information TO the CNS and motor neurons carry responses OUT of the CNS. - Together, these neurons make up the peripheral nerves - Neurons carry electrical impulses from one point to another in the body and do so very quickly - When many individual neurons come together into a single structure they make up a nerve.

4. There are two types of peripheral nerves: 1. spinal nerves - 31 pairs which come out from the spinal cord on the right and left side - many of these nerves are mixed containing both sensory and motor neurons

5. 2. cranial nerves - 12 pairs of these emerge from the ventral (underside) of the brain - they may be sensory, motor, or mixed; autonomic or somatic

6. 6.5.3 State that nerve impulses are conducted from receptors to the CNS by sensory neurons, within the CNS by relay neurons, and from the CNS to effectors by motor neurons.

7. Resting Potential - the state that a neuron is in when it is not actively sending an impulse - this neuron is said to be polarized with the inside of the cell more negatively charged than the outside. - polarity is controlled by the movement of Na + and K + ions across the cell membrane 6.5.4 & 6.5.5 Define resting potential, and action potential (depolarization and repolarization ) Explain how a nerve impulse passes along a non- myelinated neuron

9. Action Potential - represents the movement of ions into and out of the cell leading to a change in polarity, i.e. the inside of the neuron begins to become more positive - it is often said to be a self-propagating wave of ion movements in and out of the cell membrane - the impulse of the action potential is the movement or diffusion of the sodium ions in and potassium ions out of the axon which leads to depolarization i.e. the neuron has become more positive on the inside - depolarization of a segment of one segment of the cell membrane leads to immediate depolarization of the next, thus, self-propagating.

10. Generation of an action potential

11. Repolarization - the return to the resting state - this occurs as the sodium and potassium ions that have diffused across the cell membrane are actively transported to their resting potential state via a Na + K + pump - the time it takes for one neuron to send an action potential and repolarize is called the refractory period. - during this time, the neuron cannot respond to another stimulus

12. Repolarization

13. This will be addressed at a later date Please read through pg.179 now and again when we cover this. 6.5.6 Explain the principles of synaptic transmission