The divisions of the nervous system: central and peripheral (somatic and autonomic) Flashcards
What is the nervous system?
A specialised network of cells in the human body and is our primary internal communication system. It is based on electrical and chemical signals whereas the endocrine system is based on hormones.
What are the 2 main functions of the nervous system?
- to collect, process and respond to information in the environment.
- to co-ordinate the working of different organs and cells in the body.
What are the 2 subsystems of the nervous system?
Central nervous system (CNS)
Peripheral nervous system (PNS)
What is the central nervous system made up of?
The brain and the spinal cord
Describe the brain
- It is the centre of all conscious awareness
- the brain’s outer layer is cerebal cortex and is highly developed in humans
- the brain is divided into 2 hemispheres
Describe the spinal chord
- Spinal chord transmits messages to and from the brain and also to the peripheral nervous system.
- It is involved in reflex actions such as the startle response. If you put your hand on a hot kettle it is your CNS which generates the command to pull it away.
What are the 2 parts of the PNS
- Somatic nervous system
- Autonomic nervous system
What does the SNS govern?
Governs muscle movement and receives information from sensory receptors.
What does the ANS govern?
Governs vital organs in the body such as breathing, heart rate, digestion, sexual arousal and stress responses
What does the SNS do?
Transmits information to and from senses and to and from central nervous system
And controls voluntary movements (controls skeletal muscles to do this)
Therefore has both sensory and motor pathways
Commands come from the motor cortex at the top of the brain
What does the autonomic nervous system do?
Controls automatic processes
Transmits information to and from internal organs to sustain essential processes required for life
This include involuntary movements (startle response), heartbeat and breathing
Is made up entirely of motor pathways
Commands come from the brain stem (at the bottom of the brain where it joins the spine)
What are the 2 main divisions of the Autonomic nervous system
The sympathetic nervous system
The parasympathetic nervous system
Describe the sympathetic nervous system
It’s primarily involved in responses that help us to deal with emergencies (fight+flight) e.g. increasing heart rate. Neurons from the SNS travel to virtually every organ and gland within the body, preparing the body for the rapid action necessary when the individual is under threat.
Describe the parasympathetic nervous system
The PNS relaxes an individual once the emergency has passed. It slows heartbeat and reduces blood pressure. Digestion begins again.
What is the sympathetic nervous systems influence on the gut?
Slows digestion
