brain

• What is the brain mostly made of? Explain in detail.

  Billions of neurones. Embryonic stem cells in a human embryo divide to produce more and more stem cells. Once an embryo is 3 weeks old, the stem cells in the brain area start to differentiate into neurones.
• What is a neurone?

  A single specialised nerve cell.

  
• What percentage of the brain does the cerebral cortex make up?

  80%
• What is the cerebral cortex?

  The outer layer of the cerebrum. It's split into two hemispheres. The cerebrum is surrounded by the cerebral cortex.

  
• What is the function of the cerebral cortex?

  The right side of the cortex controls the left side of the body. The left side controls the right side of the body. They both have slightly different functions but together they are responsible for the senses, behaviour, language, memory and consciousness.
• Where is the cerebellum located in the brain?

  At the base of the brain.

  
• What is the function of the cerebellum?

  It controls balance and posture. It also coordinates the timing and fine control of muscle activity to ensure that movements are smooth. It's split into two halves.
• Where is the medulla oblongata located in the brain?

  At the base of the brain, beside the cerebellum.

  
• What is the function of the medulla oblongata?

  It controls your breathing rate, heart rate and reflexes such as vomiting and sneezing.
• How is the brain connected to the spinal cord?

  The mass of neurones that make up the medulla oblongata connect the brain to the spinal cord.

  
• What is the spinal cord?

  It is about the width of a finger and consists of many nerves (bundles of neurones). These nerves carry information from the brain to the rest of the body and vise versa.
• What can electrodes do during brain surgery?

  Electrodes can carry electrical currents to the brain. If the patient is awake, they can be asked to describe what they feel. A current can also make a patient do something or stop an action from occurring; this allows the functions of the brain parts to be investigated.
• What does scanning allow doctors to do in terms of the brain?

  It allows doctors to see deeper into the brain than surgery can. It also allows the study of a healthy person's brain without risking damage to them.
• What does a CT scan show?

  The shapes and structures of the brain.
• How does a CT scan work?

  An X-ray beam moves in a circle around the head and detectors measure the absorption of the x-rays. The computer uses this information to build a view of inside the body as a series of 'slices'.
• What can differences in the shapes in the brain show in a CT scan?

  These differences can be linked to the differences in the way that people think and act, thus suggesting the functions of those parts.
• What does a PET scan show?

  It shows brain activity.
• How does a PET scan work?

  The patient is injected with radioactive glucose. More active cells take in more glucose than less active cells. The radioactive atoms cause gamma rays which are detected by the scanner. More gamma rays come from parts containing more active cells.
• What does damage to the spinal cord cause?

  It reduces the flow of information between the brain and other parts of the body. This can cause loss of feeling and movement to the area below the damage.
• What can damage in the lower spinal cord cause?

  Loss of feeling and use in the legs.
• What can damage to the neck cause?

  Quadriplegia (loss of feeling and use in the arms and legs).
• Why can damage to the spinal cord never be repaired?

  Because there are no adult stem cells that can differentiate into neurones in the spinal cord, meaning new neurones can't be made to repair damage.
• What is one form of treatment involving wires for spinal cord damage? What is a limitation of this?

  Wires can be used to electrically stimulate nerves and muscles below the damage. However, patients don't regain full movement or feeling.
• What treatment are doctors developing for spinal cord damage?

  Injections with stem cells which can be inserted into the spinal cord.
• What is a brain tumour and why can it be dangerous?

  A lump in the brain caused by rapidly diving cancer cells. It can squash parts in the brain and stop them from working properly or even altogether.
• Describe two ways to treat brain tumours.

  Tumours can be cut out or their cells can killed using radiotherapy (high energy x-ray beams) and chemotherapy (injecting drugs that kill actively dividing cells).
• What are the limitations to treating brain tumours with radiotherapy and chemotherapy?

  Both methods can damage the body and the brain. Also, chemotherapy might not work due to the blood-brain barrier.
• What is the blood brain barrier?

  A natural filter that only allows certain substances to get from the blood into the brain. This may stop chemotherapy from working.

  
• Why is there a blood-brain barrier?

  It is mainly due to the cells in the capillary walls in the brain fitting together very closely.
• What is the function of the spinal cord?

  It connects the brain to the rest of the nervous system. It also carries information from the brain to the body and vise versa.