The Nervous System Flashcards
Components of the CNS
Brain
Spinal cord
PNS
Peripheral nervous system
Components of the PNS
Sensory neurones
Motor neurones
Transmit nerve impulses in only one direction (away from the cell body)
Features of motor neurones
Dendrites
Cell body
Axon
Axon
Carries the nerve impulse from the cell body
Dendrites
Make connections with other neurones
Role of the PNS
The PNS carries nerve impulses from receptors that act as the body sensors towards the CNS along sensory neurones
The role of the CNS
Takes all information contain in inputs from sensory neurones and processes it
It then sends impulses via motor neurones to effector organs
What are nerve impulses
Electrical signals transmitted from the cell body towards the axon terminals
Myelin sheath
Consists of Schwann cells which acts in a similar way to the insulation on an electric cable
Nodes of ranvier
The small gaps between the Schwann cells
Synapses
Connections between neurones
Neurotransmitters
Nerve impulses carried across the synapse by chemicals
Most common neurotransmitter
Acetylcholine
Depolarisation
The reversal of the charge difference
Polarisation
Of a nerve or muscle cell refers to the different electrical charges on either side of the plasma membrane caused by active transport of ions
Repolarisation
The restoration of the original charge difference
Pressure
Receptors detect changes in the blood
Temperature
Receptors are located in the skin and in the CNS where they detect the core body temperature
Sound
Receptors in the inner ear detect sound waves and so allow us to hear
Light
Receptors are located in the retina of the eye and are involved in vision
Touch
Receptors are a type of pressure receptor located in the skin allow us to experience a range of sensations
Pain
Receptors are located throughout the body.
Their function is to signal to the CNS when injury has occurred
