The Nervous System

• A network of nerve cells that carry messages to and from the brain and spinal cord to different parts of the body • Coordinates the behaviour of the body.

• Collect, process and respond to sensory information in the environment • Coordinate workings of different cells and organs in the body

• The central nervous system (CNS), then brain and spinal cord • Peripheral nervous system

Made up of the brain and spinal cord and has two main functions: - Control of behaviour and regulation of the body’s physiological processes - To do this, brain must receive information from the sensory receptors and send messages to the muscles and glands.

• Relay information between the brain and the rest of the body. Allows brain to monitor bodily processes and coordinate voluntary movements • Connected with specific muscles and glands and connects nerves to the PNS • Responsible for simple reflexes, without direct involvement e.g. pulling away from a hot pan.

Areas supplied by spinal nerves below the damaged site will be cut off from the brain and will stop functioning

• All the nerves outside of the CNS make up the PNS. • It relays nerves impulses from the CNS to the rest of the body back to the CNS

• Somatic nervous system • Autonomic nervous system

• Made up 12 pairs of cranial nerves (emerge directly from the underside of the brain) and 31 pairs of spinal nerves (emerge from the spinal cord) • These nerves have both sensory and motor neurons. Sensory relay messages to the CNS, motor relay information from the CNS to other areas of the body. • This system controls muscle movement, involved in reflex actions without involvement of the CNS so it can occur very quickly

• Governs vital functions like breathing, heart rate and digestion. • These involuntary actions are regulated by the ANS, and it’s autonomous

• Sympathetic nervous system • Parasympathetic nervous system

• Represents a state of physiological arousal (breathing gets faster, heart beat rapidly etc.) • Prepares the body for ‘fight or flight’ response as means of coping with stress.

• Contradicts the SNS, produces the opposite effects. • The ‘rest and digest’ response returns the body to normal resting state after the threat of stress has passed

• Increases heart/breathing rate • Dilates pupils • Inhibits digestion/saliva production • Contracts rectum

• Decreases heart/breathing rate • Constricts pupils • Stimulates digestion/saliva production • Refixes rectum

• Brain receives threat message then sends signals down to the spine • Spine sends signals to the sympathetic nervous system which prepares the flight of fight response