Biophsychology

• Sensory neurons are located in the PNS in clusters known as ganglia.
• Relay neurons are mostly found within the brain and the visual system.
• The cell bodies of motor neurons are found in the CNS but they have long axons which form part of the PNS.
• Neurotransmitters either have an excitatory or inhibitory effect on the neighbouring neuron (e.g. serotonin causes inhibition in the receiving neuron resulting in the neurone becoming more negatively charged and so less likely to fire)
• Whether a postsynaptic neuron fires is decided by the process of summation (the excitatory and inhibitory influences are summed- if the net effect is excitatory it is more likely to fire). Therefore, the action potential is only triggered if the sum of the excitatory and inhibitory signals reaches the threshold.
• Synaptic transmission= the process by which neighbouring neurones communicate with each other by sending chemical signals across the synapse that separates them.
• Sensory neurons= carry messages from the PNS to the CNS
• Relay neurons= connect sensory neurons to motor neurons or other relay neurons
• Motor neurons= connect the CNS to effects such as muscles or glands
• Function of the nervous system:

  • to collect, process and respond to information in the environment
  • to co-ordinate the working of different organs and cells in the body
• CNS= brain and spinal cord
• Spinal cord= passes messages to and from the brain and connects nerves to the PNS. It is also responsible for reflex actions.
• PNS:

  • Autonomic nervous system
  • Somatic nervous system
• Autonomic nervous system= governs vital functions in the body such as breathing , heart rate and stress responses. (Separated into the sympathetic and parasympathetic nervous systems)
• Somatic nervous system= governs muscle movement and receives information from sensory receptors
• PNS sends information to the CNS from the outside world and transmits messages from the CNS to muscles and glands
• SNS= transmits information from receptor cells in the sense organs to the CNS
• ANS= transmits information to and from internal bodily organs