AQA GCSE Biology

Revision Notes

5.2.4 The Brain

The Brain: Basics

  • The brain alongside the spinal cord is part of our central nervous system
  • The brain is made of billions of interconnected neurones and is responsible for controlling complex behaviours
  • Within the brain are different regions that carry out different functions

Structure of the Brain

  • Scientists have discovered that different regions of the brain seem to be responsible for controlling different functions, these regions include:
    • The cerebral cortex: this is the outer layer of the brain which is divided into two hemispheres. It’s highly folded and is responsible for higher-order processes such as intelligence, memory, consciousness and personality
    • The cerebellum: this is underneath the cerebral cortex and is responsible for balance, muscle coordination and movement
    • The medulla: this region controls unconscious activities such as heart rate and breathing

The Brain Structure, downloadable IGCSE & GCSE Biology revision notes

The brain is made from billions of interconnected neurones which are organised into regions

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Investigating the Brain

  • The brain is an incredibly complex and delicate organ – this makes it extremely difficult for neuroscientists to study it to find out how it works
  • Our understanding is limited because the brain is so complex and different regions can’t be studied in isolation
  • Our limited understanding means that treating brain damage and disease is very difficult; in addition, any potential treatment carries risks of further damage occurring which can lead to increased problems
    • Accidental damage could lead to speech or motor issues, or changes to personality which are permanent

Mapping regions of the brain

  • Neuroscientists have been able to map the regions of the brain to particular functions by studying patients with brain damage, electrically stimulating different parts of the brain and using MRI scanning techniques
  • Patients with brain damage can be studied to see what effect it has on them physically or on their personality or capabilities
    • The most famous example of this is Phineas Gage, a railroad construction worker who survived a large iron rod being driven completely through his head – his frontal left lobe was completely destroyed and his personality and temperament changed drastically
  • Tiny electrodes can be pushed into different parts of the brain, tiny jolts of electricity stimulate these regions and the effects can be observed
    • For example, if a region in the medulla responsible for movement is stimulated, the movement caused can be observed
  • MRI scanners are very important diagnostic tools used to study the brain and other regions of the body using magnetic fields and the effect these have on protons in the water molecules of the body
    • Functional MRIs can produce images of different regions of the brain that are active during different activities like listening to music or recalling a memory (the scanners can detect changes in blood flow – more active regions of the brain have increased blood flow)

Exam Tip

In the exam you may be asked to evaluate the benefits and risks of procedures carried out on the brain and nervous system. The benefits of procedures being carried out usually involve improving the quality of someone’s life (as the procedure is used to treat a disorder of some kind) but there are risks of more permanent damage, some of these will be because we still don’t fully understand how the brain and nervous system works!

Author: Jenna

Jenna studied at Cardiff University before training to become a science teacher at the University of Bath specialising in Biology (although she loves teaching all three sciences at GCSE level!). Teaching is her passion, and with 10 years experience teaching across a wide range of specifications – from GCSE and A Level Biology in the UK to IGCSE and IB Biology internationally – she knows what is required to pass those Biology exams.
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