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Creation's Story (18)

R W Cargill, St Monans

OUR AMAZING BRAIN

In the course of a day we may do hundreds of things, and speak or read thousands of words. But we may think millions of thoughts. All our thoughts are generated and coordinated in a brain of truly amazing structure and complexity. Many thoughts are so fleeting that we hardly notice or remember them, others are deliberate and deep. Some bring a smile, others bring anxiety and sorrow. Some will lead to actions, others we will reject. It is our thoughts which produce our words and our deeds, for better or for worse. Therefore, controlled and directed thoughts are essential for a life pleasing to God and helpful to man. So, "Think on these things", says the Bible the things that are true, honest, just, pure, lovely, of good report, things of virtue and of praise (Phil 4.8).

When God made man in His own image, He made him body, soul, and spirit. The brain is part of the body surgeons can remove it from its protective structure (the skull), hold it in their hands, and often correct something which has gone wrong through injury or disease. But no one can lay hands upon a thought it is not part of the body. Nor can anyone lay hands upon the mind it too is not a physical thing. The mind is closely related to the soul, in fact sometimes in Scripture it is identified with it. The mind and soul use and direct the thoughts - intangible, unseen, but of so much potential value to God and to man. Meditations, resolves, decisions, reckonings all involve the mind and soul; in fact these shape and mould the mind and the soul, the real and significant personality, the person who is you and only you and eternally you. Meditations and resolves are very important!

Even as the hand is required for doing and the lips for speaking, so is the brain required for thinking. Just how thoughts are produced, how memories are stored and recalled, how ideas are invented and expressed is not fully known. Even how the brain controls all the functioning parts of the body, how consciously and unconsciously it keeps us going, is only partly understood. The brain by which we do understand many things has been described as beyond our understanding. It is justifiably called the most complex structure in the universe.

The Structure of the Brain

The brain has been compared to a computer, but its capacities of memory, function, speed, and durability are far beyond the best ever made, or that ever could be made; or a control centre of a busy airport, but governing a system more complex than them all put together; or a network of information circuits hundreds of times more complex than the whole world's telephone systems - if the circuit diagram could be drawn it would cover an area of several square miles. In every respect the brain exceeds them all in complexity and efficiency.

Here are some fairly well established facts about the human brain. It is the most powerful thinking machine that can be built from the atoms in this world.

  • It weighs about 3 lbs (about 1.4 kg), bigger than that of any mammal except the whale and the elephant. In relative terms the human brain is far bigger, about 2% of body weight. The elephant's brain, about four times larger, is only about 0.1% of its body weight. This relative size is another feature which makes man unique in creation.
  • It contains about a hundred billion neurons, each connected to about 10,000 others. A pinhead-size piece of the "grey matter" of the brain contains around 60,000 neurons. During the development of a baby in the womb 250,000 neurons are formed per minute. The neurons in one brain are more numerous than the stars in the Milky Way.
  • Our brain uses about 20% of our body's energy. In other mammals this figure is 5 10%. The brain is supplied by energy and nutrients from the blood stream through an intricate system of fine blood vessels.
  • The brain can process around 1 million million million information signals per second (about a hundred million times faster than any supercomputer).
  • Nerve fibres convey information between brain cells. In the brain their total length is about 300,000 miles, while outside of it another 240,000 miles of nerve fibres (about one thousandth of a millimetre in thickness) carry commands and information to every part of the body. The signals are carried at about 100 mph (40 metres per second).

Brain Cells or Neurons

Each neuron is itself a marvel of complexity and function. Like all our cells it has a nucleus in which DNA is stored and used. The body of the neuron has many long streamers or dendrites (like the branches of a tree) which are spread out to reach other cells and receive impulses from them. It also has a longer and thicker fibre called an axon which carries impulses to other cells. Connection between the neurons takes place from the end of the axon of one to the dendrites of another across a narrow gap called the synapse by means of chemical signals called neurotransmitters. When a signal is thus transmitted it is like a switch being turned on. Usually a whole series of switches are turned on at once, creating a pathway among thousands of cells which is perhaps a thought pathway or a memory trace. The result of this thought may then fire off signals through nerve fibres to other parts of the body to produce action. Can you sense the wonder of all this how a thought is produced and then becomes a word or a deed?

When certain skills are learned, like reading, writing, or counting, pathways are created and constantly reinforced by regular usage. When memories are recalled, pathways are again activated, but with decreasing use these may become less effective and we "can't remember". Also as we get older, some neurons may die off and usually they are not replaced. Some connections cannot be made, so we forget more!

There are many types of neurons. Sensory neurons carry information from our sense organs (e.g. eyes, ears); motor neurons carry information to muscles and glands; interneurons connect between the sensory and motor neurons  they make up around 97% of the whole central nervous system. Most neurons are less than a millimetre in length, but some of the motor neurons in the spinal chord, for example, are about 1 metre long. Each has been individually designed and made for its purpose, from the shape and size of the cell right down to the electrical and chemical processes which make the connections. The whole is designed to co-operate as one brain and identify a human being. How long would all that take to evolve? It never would or could! It was created, a marvel and a miracle of God's own devising.

Sectors of the Brain

Looked at as a whole, the brain consists of two hemispheres, each of which controls the opposite side of the body. Each is covered by a 3 millimetre thick layer of nerve cells called the cerebral cortex. This is extensively convoluted (folded) to give it a large surface area. The cortex has both motor and sensory functions, and in fact different sections can be related to different abilities. For example, the sections which control and sense the hands with their intricate movements and the lips with theirs, are much bigger than those which control the neck or the hip.

The brain also contains other key organs which coordinate activity, such as the pituitary gland and the hypothalamus. The pituitary secretes hormones which are carried by the blood to other glands to stimulate their actions. The hypothalamus, the size of a pea, is an amazing control centre for eating, drinking, sleeping, body temperature, and many other important automatic functions like breathing and heart beat. It also controls the pituitary.

The Mind

Beyond the brain, and yet depending on it, is the mind. The brain receives information through the senses, processes it into thoughts and memories, and the mind interprets it all in a way which influences, and is influenced by, the soul or personality of the individual.

The Scriptures often refer to the mind, and sometimes the "heart" as the seat of our emotions and desires. Thus, "As he thinketh in his heart, so is he" (Prov 23.7); "Out of the heartproceed evil thoughts" (Mk 7.21); "Love the Lord thy God with all thy heart, and all thy soul, and with all thy mind" (Mk 12.30); "Let this mind be in you, which was also in Christ Jesus" (Phil 2.5).

How important to use our brains to think well, to focus and train our minds to love God, to reflect the mind of Christ. 

To be continued.

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