Synaptic transmission is the process where an electrical impulse (action potential) passes across the synaptic gap. Electrical impulses reach the presynaptic terminal, which triggers the release of neurotransmitters, which then cross the synapse from vesicles, it is taken up by the postsynaptic receptor of the nest neurone. The chemical message is then converted into an electrical impulse. Stimulation of postsynaptic receptors by neurotransmitters result in either excitation or inhibition. Some neurotransmitters such as serotonin are inhibitory, increase the negative charge of the postsynaptic neuron making it less likely the neurone will fire. Other neurotransmitters, like Adrenaline are excitatory, and increase the positive charge of the postsynaptic neurone, making it more likely that the neurone will fire.
Central Nervous system: Brain and Spinal cord- cord responsible for reflex actions- it passes messages to and from the brain- connects nerves to the PNS
Peripheral nervous system transmits messages via millions of neurones- sub-divided into autonomic nervous system and somatic nervous system
Autonomic NS: governs vital functions of the body such as breathing, heart rate and digestion- homeostasis- splits into Sympathetic and parasympathetic nervous system
Somatic NS: controls muscle movement and receives information from sensory receptors
Sympathetic nervous system: involved in responses that prepare the body for fight or flight- boosts heart rate, breathing, digestion supressed- when a stressor is perceived the hypothalamus triggers activity in the Sympathetic branch- turns body to the physiologically aroused state
Parasympathetic nervous system is to relax the body, and return us to our ‘normal’ resting state, decrease heart rate, stimulates digestion
