Nervous system

• The nervous system is split into the central nervous system and the peripheral nervous system
• The central nervous system is made up of the brain and spinal cord
• the peripheral nervous system is made up of the autonomic nervous system and the somatic system
• The somatic system is your voluntary responses
• The autonomic system is your involuntary responses
• The autonomic system is made up of the sympathetic system and the parasympathetic system
• The sympathetic system and parasympathetic system are antagonistic
• The sympathetic system prepares the body for action
• The parasympathetic system controls activities at rest
• The autonomic nervous system is part of the peripheral nervous system and therefore transmits information from the central nervous system
• The parasympathetic system causes constriction of the pupil and the sympathetic system causes dialation
• The parasympathetic system causes stimulation of saliva and the sympathetic system inhibits saliva
• The parasympathetic system decreases breathing rate nd the sympathetic system increases breathing rate
• The parasympathetic system stimulates gut action and the sympathetic system inhibits gut action
• The parasympathetic system stimulates bladder contraction and the sympathetic system relaxes the bladder
• The parasympathetic system decreases heart rate and the sympathetic system increases it
• The parasympathetic system decreases adrenal gland secretion and the sympathetic system increases adrenal gland secretion
• The parasympathetic system causes sexual arousal and the sympathetic system causes ejaculation or orgasm
• Neurones have extensions called dendrites and one long extension called the axon
• Myelin sheaths are formed from Schwann cells
• Schwann cells have lipid rich cell membranes
• Gaps in the myelin sheath are known as Nodes of Ranvier
• Reflex arcs don't involve many synapses, which are slow to transmit across neurones
• Although reflexes occur at the point of response, some signals are still sent to the brain. This may result in nothing but sometime allows the brain to override the response if its comprehensive decision making process deems this necessary