the nervous system

nervous system

• a specialised network of cells and the body’s primary internal communication system.

• thought and behaviour are caused by activity in the nervous system.

• two main functions are: to collect, process and respond to information in the environment, and coordinate the working of different organs and cells.

central nervous system

• consists of brain and spinal cord.

• controls systems for life functions and conscious psychological processes.

brain

• cerebral cortex → highly folded grey matter on outer layer of brain, involved in a variety of higher cognitive, emotional, sensory and motor functions.

• two symmetrical hemispheres → left (language, ‘rational’ half of the brain, associated with analytical thinking and logical abilities) and right (involved with musical and artistic abilities).

• four distinct lobes → frontal, parietal, occipital, and temporal.

• under cerebral cortex is the area of the brain which is more primitive and concerned with vital functioning and instinctive behaviour.

spinal cord

• a bundle of nerves, which runs from your brain along a canal in your backbone.

• main function is to send nerve signals from the brain to the body, and from the body to the brain.

• involved in reflex actions, e.g. startle response.

• the brain is connected to the spinal cord by the brain stem.

peripheral nervous system

• consists of nerves outside the brain and spinal cord.

• divided into two major systems- somatic nervous system and autonomic nervous system.

• involved in interaction with outside world.

• passes info between the CNS, organs and the external world.

somatic nervous system

• the voluntary movement of skeletal muscles.

• consists of nerves that carry messages to the eyes, ears, skeletal muscles.

• transmits info between the CNS and the senses.

• involved in the interaction with the outside world.

autonomic nervous system

• the involuntary movement of non-skeletal muscles.

• transmits info from CNS to internal organs and non-skeletal muscles.

• transmits info between organs and the CNS to cause involuntary bodily activities.

• consists of sympathetic and parasympathetic nervous systems.

sympathetic nervous system

• activated in state of arousal.

• activates ‘fight or flight’ response.

• prepares the body’s resources for immediate action, by producing increased heart and respiratory rate, increasing blood flow to the muscles and pupil dilation.

parasympathetic nervous system

• activated after threat is over to rest and relax.

• allows the body to return to homeostasis.

• the person’s heart and respiratory rate decrease to normal levels, blood flow decreases, pupils return to normal size.

• this is vital for the individual to conserve energy and not to become exhausted.