Mammalian Nervous System (OCR A Level Biology)

Revision Note

Test yourself
Alistair

Author

Alistair

Last updated

Mammalian Nervous System

The structural organisation of the nervous system into the central and peripheral nervous systems

  • The human nervous system consists of the:
    • Central nervous system (CNS) – the brain and the spinal cord
    • Peripheral nervous system (PNS) – all of the nerves in the body

  • The human nervous system allows us to make sense of our surroundings and respond to them, as well as to coordinate and regulate body functions
  • Information is sent through the nervous system as nerve impulses – electrical signals that pass along nerve cells known as neurones
  • A bundle of neurones is known as a nerve
  • Neurones coordinate the activities of sensory receptors (eg. those in the eye), decision-making centres in the central nervous system, and effectors such as muscles and glands

The human nervous system, IGCSE & GCSE Biology revision notes

The human nervous system

The functional organisation of the nervous system into the somatic and autonomic nervous systems

  • Functionally, the nervous system can be divided into two parts:
    • The somatic nervous system
    • The autonomic nervous system

  • The somatic nervous system is required for the voluntary control of body movements
  • The somatic nervous system consists of three types of nerves:
    • Sensory nerves - these consist of sensory neurones and carry impulses from sense organs to the CNS
    • Motor nerves - the consist of motor neurones and carry impulses from the CNS to muscles and glands
    • Spinal nerves - found in the spinal cord, these are mixed nerves that consist of both sensory and motor neurones

  • The autonomic nervous system is a self-controlling system that is required for involuntary actions and functions, such as heart rate, regulation of blood vessel diameter, and peristalsis in the gut
  • The autonomic nervous system can itself be divided into two parts:
    • The sympathetic nervous system, which controls 'flight-or-fight' responses
    • The parasympathetic nervous system, which controls the 'rest and digest' system

The 'flight-or-fight' response controlled by the sympathetic nervous system

  • The sympathetic nervous system controls the release of adrenaline, a hormone produced by the adrenal glands
  • This hormone is released during a fight-or-flight response
    • For example, when a zebra sees a lion starting to chase it

  • It causes the heart rate to increase
  • The increase in heart rate is beneficial as it allows for a rapid increase in blood supply to respiring muscles
    • This means the muscles will have more oxygen and glucose for respiration

  • It enables high-intensity activities like running away from a predator to be an immediate response

Examiner Tip

Don't get nerves and neurones confused - you could potentially lose marks for this if you use the terms interchangeably in an exam! Nerves are made up of bundles of nerve cells, known as neurones. Look at the diagram again to make sure you understand the difference.

You've read 0 of your 10 free revision notes

Unlock more, it's free!

Join the 100,000+ Students that ❤️ Save My Exams

the (exam) results speak for themselves:

Did this page help you?

Alistair

Author: Alistair

Expertise: Biology & Environmental Systems and Societies

Alistair graduated from Oxford University with a degree in Biological Sciences. He has taught GCSE/IGCSE Biology, as well as Biology and Environmental Systems & Societies for the International Baccalaureate Diploma Programme. While teaching in Oxford, Alistair completed his MA Education as Head of Department for Environmental Systems & Societies. Alistair has continued to pursue his interests in ecology and environmental science, recently gaining an MSc in Wildlife Biology & Conservation with Edinburgh Napier University.