The Brain Bio Factsheet

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B io Factsheet
January 2002 Number 101
The Brain
The brain is vital for the coordination of responses and activities. The CSF is a type of lymph which effectively bathes the brain and spinal
This Factsheet summarises: cord as it is contact with both the inside and outside. It provides the
· The position, structure and functions, of the human brain; neurones with vital nutrients and oxygen, and removes waste products. It
· Factors which affect brain function; also contains lymphocytes to prevent infection. To assist the circulation of
CSF, the epithelial cells lining the ventricles and central canal have cilia on
· The symptoms and causes of Alzheimer's disease as an
their surface.
example of brain malfunction.
This Factsheet is restricted to the brain. Other factsheets, which cover Remember - inflammation of the meninges is meningitis which is caused
closely related information that you may wish to refer to, are: by a viral or bacterial infection of the meninges.
No. 20. Nerves and synapses.
No. 56. The autonomic nervous system. Fig 2 Vertical section through a human brain
No. 58. Reflex actions.
The structure of the human brain cerebrum
The brain is the coordinator for the human body. It contains approximately corpus
100 000 million nerve cells. The numerous connections made by the fibres callosum
of these cells are responsible for our capacity for conscious thought.
ventral dorsal
It is often thought that brain size is proportional to intelligence, on the side side
basis that it has been observed that the size increased during the evolution
of vertebrates. Mammals have the largest brain in relation to body size, hypothalamus
midbrain region
making up roughly 2.33% of body weight. pituitary body
ventricle (fourth)
Fig. 1 Side view of human brain pons
right cerebral medulla oblonga
hemisphere spinal cord
frontal Exam hint - watch your spelling! Some brain regions if spelt
lobe incorrectly can be confused, for example the cerebellum and the
temporal lobe pons The embryonic brain contains three regions, the forebrain, midbrain and
hindbrain. These structures differentiate into the more complex adult
cerebellum part of the three structures of the brain:
meningeal membranes
medulla oblongata which cover the brain Table 1. Regions of the brain
(brain stem) and spinal cord
Embryonic brain Adult brain
Forebrain Cerebral hemispheres, hypothalamus, thalamus
The basic structure of the brain is always the same. The main part is the
cerebrum which is divided into two halves, called cerebral hemispheres, Midbrain Midbrain
which are found either side of the brain stem. The left and right cerebral Hindbrain Medulla oblongata, cerebellum and pons
hemispheres are connected by a mass of nerve fibres called the corpus
callosum. Each cerebral hemisphere consists of four main lobes: the frontal,
temporal, occipital and parietal lobes. The medulla oblongata gradually Functions of the parts of the brain
tapers into the spinal cord. At the back of the main brain (cerebrum) is the The functions of the brain are localised into specific regions. It has been
cerebellum (or `little brain'). possible to assign functions to the different regions by a number of
techniques. Originally the only data available was from patients who had
The brain and the spinal cord make up the central nervous system (CNS). suffered a brain trauma. By determining which part of the brain had been
Like the spinal cord the brain is made of grey and white matter, and has a damaged and observing the effect of the damage, a function for that area
central canal, which in the brain is expanded into cavities called ventricles. could be suggested. More recently, however, electrodes have been used to
The brain and spinal cord are surrounded by a protective three-membrane stimulate specific regions of the brain and the response observed. Modern
system called the meninges. The space between the inner two meningal techniques such as MRI (magnetic resonance imaging) scans have given
membranes is filled with cerebro-spinal fluid (CSF), as are the ventricles information as to which areas of the brain are stimulated during different
and central canal. activities.

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The Brain Bio Factsheet
Exam Hint - make sure you know which parts of the brain are listed in If this area is damaged, visual images cannot be processed for example, a
your specification ­ different boards ask for different regions. person may see an old friend, but will not recognise them. Also found here
is the auditory association area allowing the recognition of sounds.…read more

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The Brain Bio Factsheet
Exam hint - when writing the functions make sure you always say, for Practice Questions
example, `control of osmoregulation' as just `osmoregulation' would 1. The diagram below shows a human brain as seen from the side.
not get the marks.
Alzheimer's Disease
If nerve cells are damaged they are not replaced by cell division as their cell
cycle is too long and they are too specialised.…read more


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