Contents
Divisions of the nervous system
Structure and function of neurons
Endocrine system
Fight or flight response
Localisation of function in the brain
Ways of studying the brain
Biological rhythm
,Divisions of the nervous system
The nervous system
The nervous system is a network of specialised cells capable of transmitting information
around the body. It helps us to co-ordinate activity in different systems and allows us to
detect what is happening in our environment and our bodies.
Acts to affect what happens after information processed.
It is organised into divisions:
Central Nervous System
Processes information – comprises of brain and spinal cord:
- Brain
o Centre of all conscious awareness / maintains life
o Outer layer (cerebral cortex)
Responsible for higher order thinking skills
o Divided into two hemispheres
- Spinal cord
o Extension of the brain
o Responsible for reflex action – e.g. pulling hand away from hot surface
o Controls regulation of internal processes
o Facilitates transferal of messages to and from brain to the PNS
For the brain to control internal processes, when it receives sensory info (from the sensory
receptors) it should send a message to the muscles and glands in the body.
Peripheral Nervous System
Transmits info to and from the CNS from the senses (thereby transferring messages to the
whole body from the brain / from the whole body to the brain). This happens via neurons.
It is subdivided into 2 parts:
Autonomic involuntary, automatically relays messages to and from organs and governs
vital bodily functions – e.g. Breathing Heart rate Arousal Digestion Stress
Somatic voluntary, controls muscle movement – receives info from sensory receptors
which is relayed from the brain
The main job of the SNS is to receive sensory info (e.g. visual info from eyes). It directs
muscles to react and move. It has sensory and motor pathways, connecting the CNS to the
senses – controlling skeletal muscle movement and controlled by motor cortex. Some
elements of this system can be involuntary (e.g., in the reflex arc, muscle contraction is not
controlled) .
, The ANS is essential in sustaining life processes. It monitors and controls what happens
inside our bodies as we can only function under a relatively narrow range of conditions and
maintaining these conditions (homeostasis) requires monitoring and response to changes.
Organisms need to be able to adjust internal conditions in response to the environment. It has
purely motor pathways as it controls internal organs.
Differences between autonomic and somatic:
- ANS = smooth muscles and glands
SNS = skeletal muscles
- ANS = involuntary
SNS = under conscious control
- ANS = purely motor
SNS = sensory and motor pathways
- ANS = control centres in the brain
SNS = commands from the motor cortex
Divisions of autonomic
The sympathetic (συμπαθος) increases bodily activity whilst the parasympathetic (παρα-
συμπαθος) maintains or decreases activity.
The sympathetic nervous system responds to a perceived threat:
- Physiological changes that prepare the body
- Flight or fight response / alarm response
The parasympathetic nervous system restores normal physiological functioning when the
threat has passed.