The structure of the brain

In a nutshell

The central nervous system (CNS) is made of the spinal cord and brain and contains lots of neurones. The CNS can be seen as the control centre of nervous coordination. The spinal cord and brain are intricately linked via nerves and so they work with each other. This summary explores the different structures of the brain and how brain function is investigated.

The brain

The brain is the main control centre of the body, giving all our organs instructions on how to work. There are some key areas to the brain.

Biology; Cells and control; KS4 Year 10; The structure of the brain — 1. Cerebral cortex, 2. Cerebellum, 3. Brainstem (including medulla oblongata)

BRAIN STRUCTURE	FUNCTION
Cerebral cortex	The largest part of the brain making up the two hemispheres. Consciousness, language processing, decision making and all cognitive functions take place here.
Cerebellum	A small round structure found at the bottom/back of the brain. This controls fine-tuning of motor movement to make them precise.
Medulla oblongata	A structure that is part of the brain stem. Controls unconscious processes such as breathing and heart rate.

Note: The following section is for students studying the higher tier specification.

Investigating the brain

It can be quite difficult to investigate brain function. This is because the brain is very delicate and if neurones in the brain get damaged, they are not regenerated. Therefore, cutting open a live brain to test what different parts do risks damaging a patient's brain and giving them severe disorders.

To investigate brain anatomy, post mortem samples are analysed. These are brain tissues that have been collected after a person has died but these cannot tell us what different parts of the brain do.

Another way to investigate brain anatomy is to electrically stimulate specific parts of the brain by pushing an electrode into it and observing the response it produces. However, this has to be done very carefully as it can damage the brain.

Experiments can be designed that activate different parts of the brain and look at these through brain scans such as PET scans, MRI scans and CT scans. This is a much less invasive method, but it means that we have to take lots of images of the brain which can be very time consuming.

scan	Description
CT	The patient is given a radioactive tracer that will travel into the brain via the blood vessels. This will provided a shaded picture on the scan which will show the spread of the tracer through the structures of the brain.
PET	The patient is given a radioactive form of glucose that will travel into the brain to respiring tissues. This will show areas of the brain that are very active and using a lot of energy at the time of the scan.
MRI	The patient is put in a magnetic scanner. The scanner takes multiple pictures at different levels and different angles so that many images can provide lots of detail about specific areas of the brain.

Diseases

It is difficult to treat brain diseases as we still don't fully understand how the brain works or which areas are responsible for different things, so if we give a medication for a disease, we don't know if it will actually work. Some medicines may also not cross the blood-brain barrier.

This a barrier that the brain has to keep its blood flow separate to the body, which prevents any infection in the body reaching the brain. While much progress has been made in research into the brain and treatments for neurological diseases, there is still a lot to discover.