The main parts of the brain are:
The Cerebrum - This part of the brain is concerned with all higher mental
Functions, such as thinking and memory. It is made up of two halves or hemispheres. The right cerebral hemisphere controls the left side of the body and the left cerebral hemisphere controls the right side of the body.
Each cerebral hemisphere is divided into four areas, known as lobes: the frontal, parietal, temporal and occipital lobes. Each lobe controls a different range of activities.
The Cerebellum - This is the back part of the brain and is concerned with balance and coordination. These activities are carried out automatically (subconsciously) by this area of the brain and are not under a person's control.
The Brain stem - This controls the basic functions essential to maintaining life, including blood pressure, breathing, heart beat and also eye movements and swallowing. It is the bottom part of the brain and connects the cerebral hemispheres to the spinal cord.
The limbic system -is one of the association areas in the cerebrum which integrates information from sense organs and from other areas of the brain. It is closely involved with emotions and with the formation and storage of memories.
One area of the brain that is essential in forming new memories is a part of the limbic system called the hippocampus.
This is used when we make new memories. We are not sure how it does this, but it is certain that synapses are involved. Synapses may be strengthened in some way, or perhaps completely new synapses are made.
Transmission of an action potential
The function of a neurone is to transmit information, in the form of action potentials, along itself. When a neurone is stimulated, an action potential is generated. Sodium channels open in the cell surface membrane.
This allows sodium ions to flood in down their electrochemical gradient. This temporarily reverses the charge across the membrane, so that it becomes positive inside, and is said to be depolarised.
*The graph shows the events that take place at one point in the axon membrane.
What is meant by Saltatory conduction ?
A fatty material called myelin, which is produced by Schwann cells, surrounds the axons of many neurons. There are gaps in this sheath, called nodes of Ranvier. Action Potentials jump from node to node and so travel more swiftly than in a non-myelinated neurone.
The structure and role of a synapses
Synapses help to ensure that nerve impulses only pass one way along a neurone. They also help to link many different pathways within the nervous system, allowing information from different sense organs or different parts of the brain to be integrated.
Differential growth-
Is when different organs show patterns of growth that are not the same as the overall pattern. One of the noticeable things about an infant is that, the head is much larger in proportion to the rest of the body than in an adult. In an embryo and foetus, the head grows more rapidly than other parts of the body. This is related to the growth of the nervous tissue inside it, forming the brain.
A foetus’s lymphatic system grows more slowly than other parts of the body. This system is involved in the immune response.
The foetus does not need it while it is in the uterus because its mother’s antibodies cross the placenta and protect the foetus from pathogens. After birth, the child’s antibody levels fall although it will still receive some from its mother if she breastfeeds. About one month after birth, the infant begins to make its own antibodies. It is not until it is 12 to 20 months old that the lymphatic system is fully formed and the child’s body can mount a full immune response. The reproductive organs complete their development even later in life. They do begin to develop while the foetus is in the uterus and by the time a girl baby is born, she will already have large numbers of eggs in her ovaries. But the main of the reproductive organs does not take place until puberty, In boys, this somewhere between the ages of 8 and 16 years, while in girls it normally happens between 7 and 15.
*The graph shows the Differential growth of some organ systems
The Diet for a growing child
A growing child needs a good diet to help all the organs of the body to grow and develop fully. Nutrients that are required as a child grows up are; Carbohydrates, Proteins, Lipids, Vitamin A, Vitamin D, phosphorus and calcium, folic acid and iron.
Carbohydrates and lipids – are needed for energy, lipids also supply the raw materials for making cell membranes and the protective sheaths which form around many nerve cells. There is evidence to show that the presence of certain kinds of fatty acids in the diet can have a significant effect on brain development. It would therefore not be appropriate to feed a growing child a diet, which is extremely low in fats.
This shows just how important our diets can be in relation to growth and memory.
Ageing and the nervous system
All parts of the nervous system, both central and peripheral, undergo deterioration as we age. It was thought that neurones in the brain began to die from the age of about 18 and they were not replaced. There is now some evidence to suggest that at least partial replacement may occur but, nevertheless, some older people do not have the faculties that they had when they were younger. However, many people retain a sharp mind into their eighties and beyond.
The Ageing process in the central nervous system can lead to a reduction in mental abilities and sometimes to dementia. Alzheimer’s disease is a form of dementia in which cells in parts of the cerebral cortex die. The cause is not known, and so far no successful treatments have been found.
With aging, our brains seem to lose cells in areas that produce important neurotransmitters (chemicals that carry information between neurones). Decreasing the numbers of these cells and their ability to make the right kinds of enzymes upsets the delicate balance of these chemical messengers.
Other changes occur in the brain's white matter, which contains nerve cell fibres, through which communication with other cells takes place.
How these changes affect memory is not entirely clear, but it may be that they make cell-to-cell communication less efficient.
Storing New Memories
As a person gets older, their ability to create new memories may be affected, making it more difficult to learn new things. It's not that they forget more easily; it may simply take longer to learn information in the first place. This means they may have to pay closer attention to new information that they want to retain. They may also need to try .
When people of all age groups learn something, they retain it equally well, even if the older people need a bit more time to learn it, and perhaps, to retrieve it.
A substantial number of 80-year-olds perform as well as people in their 30s on difficult memory tests.
Techniques to improve memory
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Relax: Tension and stress are associated with memory lapses. Managing stress improves memory.
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Concentrate: Your teachers were right: If you want to recall something later, pay attention.
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Focus: Try to reduce distractions and minimize interferences.
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Slow down: If you're rushing, you may not be focused or paying full attention.
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Organize: Keep important items in a designated place that is visible and easily accessed.
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Write it down: Carry a notepad and calendar, and write down important things.
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Repeat it: Repetition improves recall. Try repeating names when meeting new people, or repeating facts when you're learning new information.
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Visualize it: Associating a visual image with something you want to remember can improve recall.
