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
- 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)
6.5.2 Draw and label the
structure of a motor neuron
- 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.
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
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
6.5.3 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.
6.5.4 & 6.5.5 Define resting potential, and action
potential (depolarization and repolarization)
Explain how a nerve impulse passes along a nonmyelinated neuron
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
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.
Generation of an action potential
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
Repolarization
6.5.6 Explain the principles of synaptic
transmission
This will be addressed at a later date
Please read through pg.179 now and
again when we cover this.