CNS
The CNS consists of the brain and the spinal cord. The brain provides conscious awareness
and is involved in all psychological processes. The brain consists of many regions, which are
responsible for different functions.
For example, the brain consists of four main lobes:
● frontal lobe
● parietal lobe
● temporal lobe
● occipital lobe
The occipital lobe processes visual information; the temporal lobe processes auditory
information; the parietal lobe integrates information from the different senses and therefore
plays an important role in spatial navigation; the frontal lobe is associated with higher-order
functions, including planning, abstract reasoning and logic.
The brainstem connects the brain and spinal cord and controls involuntary processes, including
our heartbeat, breathing and consciousness.
The role of the spinal cord is to transfer messages to and from the brain, and the rest of the
body. The spinal cord is also responsible for simple reflex actions that do not involve the brain,
for example jumping out of your chair if you sit on a drawing pin.
PNS
The role of the peripheral nervous system (PNS) is to relay messages (nerve impulses) from the
CNS (brain and spinal cord) to the rest of the body.
The PNS consists of two main components:
1) the somatic nervous system and
2) the autonomic nervous system
The somatic nervous system facilitates communication between the CNS and the outside world.
The somatic nervous system is made up of sensory receptors that carry information to the
spinal cord and brain, and motor pathways that allow the brain to control movement. Therefore,
the role of the somatic nervous system is to carry sensory information from the outside world to
the brain and provide muscle responses via the motor pathways.
The autonomic nervous system plays an important role in homeostasis, which maintains internal
processes like body temperature, heart rate and blood pressure. The autonomic nervous
system only consists of motor pathways and has two components: 1) the sympathetic nervous
system and 2) the parasympathetic nervous system.
The sympathetic nervous system is typically involved in responses that prepare the body for
fight or flight. Impulses travel from the sympathetic nervous system to organs in the body to help
us prepare for action when we are faced with a dangerous situation. For example, our heart
rate, blood pressure and breathing rate increase, while less important functions like digestion,
salivation and the desire to urinate are suppressed.