heart short essay english

The human body is divided into many different parts called organs.  All of the parts are controlled by an organ called the brain, which is located in the head.  The brain weighs about 2.75 pounds, and has a whitish-pink appearance.  The brain is made up of many cells, and is the control centre of the body.  The brain flashes messages out to all the other parts of the body.  The messages travel in very fine threads called nerves.  The nerves and the brain make up a system somewhat like telephone poles carrying wires across the

 

 

city.  This is called the nervous system.      The nerves in the body don't just send messages from the brain to the organs, but also send messages from the eyes, ears, skin and other organs back to your brain.  Some nerves are linked directly to the brain.  Others have to reach the brain through a sort of power line down the back, called the spinal cord.  The brain and spinal cord make up the central nervous system.      The brain doesn't just control your organs, but also can think and remember.  That part of the brain is called the mind.                         PROTECTING THE BRAIN              Twenty-eight bones make up the skull.  Eight of these bones are interlocking plates.  These plates form the cranium.  The cranium provides maximum protection with minimum weight, the ideal combination.  The other twenty bones make up the face, jaw and other parts of the skull.       Another way the brain keeps it self safe is by keeping itself in liquid.  Nearly one fifth of the blood pumped by the heart is sent to the brain.  The brain then sends the blood through an intricate network of blood vessels to where the blood is needed.  Specialized blood vessels called choroid plexuses produce a protective cerebrospinal fluid.  This fluid is what the brain literally floats in.           A third protective measure taken by the brain is called the blood brain barrier.  This barrier consists of a network of unique capillaries.  These capillaries are filters for harmful chemicals carried by the blood, but do allow oxygen, water and glucose to enter the brain.       THE DIFFERENT SECTIONS OF      THE BRAIN       The brain is divided into three main sections.  The area at the front of the brain is the largest.  Most of it is known as the cerebrum.  It controls all of the movements that you have to think about, thought and memory. The cerebrum is split in two different sections, the right half and the left half.        The outer layer of the cerebrum is called the cortex.  It is    mainly made up of cell bodies of neurons called grey matter.  Most  of the work the brain does is done in the cortex.  It is very wrinkled and has many folds.  The wrinkles and folds give the cortex a large surface area, even though it is squeezed up to fit in the skull.        The extra surface area gives the cerebrum more area to work.  Inside the cortex, the cerebrum is largely made up of white matter.  White matter is tissue made only of nerve fibres.        The middle region is deep inside the brain.  It's chief purpose is to connect the front and the back of the brain together.  It acts as a "switchboard", keeping the parts of your brain in touch with each other.        The back area of the brain is divided into three different parts.  The pons is a band of nerve fibres which link the back of the brain to the middle.  The cerebellum sees to it that all the parts of your body work as a team.  It also makes sure you keep your balance.        The medulla is low down at the back of your head.  It links the brain to the top of the spinal cord.  The medulla controls the way your heart pumps blood through your body.  It also looks after your breathing and helps you digest food.               THE DIFFERENT PARTS OF THE     BRAIN  THE BRAINSTEM:     The brainstem is one of the oldest parts of the brain.   It controls such functions as breathing, blood pressure, swallowing and heart rate.     THE HYPOTHALMUS:      This part of the brain is located directly above the brain stem.  The hypothalmus controls basic drives like hunger and sex and as well as our response to threat and danger.  The hypothalmus also controls the pituitary.   THE PITUITARY:      The pituitary produces hormones such as testosterone that circulate through out the body.       THE THALAMUS:       The thalamus is like a relay area; it receives messages from lower brain areas such as the brainstem and hypothalmus and sends them to the two brain hemispheres.  The thalamus is located in between above the lower brain and under the two hemispheres.   THE DIFFERENT SECTIONS OF THE BRAIN:      Most of the above mentioned parts of the brain were produced early in evolution but the higher mammals especially humans went on to produce a sort of "thinking cap" on top of these parts.  This "thinking cap" was divided into two different parts, the left hemisphere and the right hemisphere.       If the left side of your brain is more developed like most people's are, you are right handed.  On the other hand if the right side of your brain is more developed, then you will be left handed.  The right side of your brain is more artistic and emotional while  the left side of your brain is your "common sense" and practical side, such as figuring out math and logic problems.            THE CEREBELLUM:      One of the most important part of the Human brain is the cerebellum.  The cerebellum is involved with the more complex functions of the brain and sometimes is even referred to as "the brain within the brain".   The cerebellum acts as a control and coordination centre for movement.        The cerebellum carries small "programs" that have been previously learned.  For example, how to write, move, run and jump are all previously learned activities that the brain recorded and can playback when needed.  Every time you practice, the brain rewrites the program and makes it better.      You may have heard the saying "practice makes perfect".  Well this saying is not entirely true; another way of "practising" is just to imagine what you wish to do.  Since the cerebellum can't actually feel, it will think that you are doing what your imagining and respond by rewriting it's previous program and carrying out any other actions needed for that function.  This is one why to explain wet dreams.   THE CEREBRAL CORTEX:      The cerebral cortex makes up the top of the two hemispheres of the brain.  The cortex is a sheet of greyish matter which produces our thoughts, language and plans.  It also controls our sensations and voluntary movements, stores our memories and gives us the ability to imagine, in short it's what makes humans, humans.       IN THE FUTURE      Today many experiments are being conducted that may be break through's for the future.  For instance "brain grafting" is one procedure that may be used in the future.  Brain grafting is to transplant a very thin layer of brain skin from one person to another.  This would result in control of parkinson's disease and other seizure related diseases.      Another radical idea that has already been successfully been tried on rhesus monkey's is, brain transplants.  The ethics and legal problems for such a transplant would probably never let this operation be performed on humans.  This is because the person would not be the same, would not have the same memories or the same abilities that the host body had had.       The last idea of the future that we will list is called "artificial hearing and seeing".  Artificial seeing is achieved by planting sixty-four small electrodes in front of the visual cortex of the brain.  The electrodes are connected to a small camera that is some where on the person's ear.  A computer is attached to the camera.  The computer sends the images from the camera directly to the implanted electrodes.  They flash as the picture from the camera, thus enabling the person to somewhat see.        Artificial hearing is much more complicated then artificial seeing.  First a electrodes must be planted in the brain.  Then through a microphone a computer produces electrical pulses that are then sent to the electrodes in the brain.          But as of yet these procedures are not practical first because of the size of the computer, it cannot be taken out of the laboratory second the cost of the package and third the risks involved.        CONCLUSION      After all of the work and research that we have done it is very evident to us that the brain is one of the most wondrous organs that humans could have.  It guides us through almost every second of our life.  Even after exploring vast and distant sky's to the microorganisms that exist today, the brain has never ceased to amaze us and probably never will.     BIBLIOGRAPHY  1. The Brain and Nervous System by Lambert, Mark  copyright Macmillan Education, 1988  2. The Brain and Nervous System by Parker, Steve copyright Franklin Watts, 1990  3. Encyclopedia Britannica by Britannica, Encyclopedia Inc. copyright Encyclopedia Britannica Inc., 1986  4. The Incredible Machine by Geographic, National Society copyright Geographic, National Society, 1992      GLOSSARY artificial hearing:  When a person is able to hear but not naturally.  artificial seeing:  When a person is able to see but not naturally.  blood brain barrier:  A set of special capillaries that are only found in brain.  There purpose is to filter the blood so only oxygen, glucose and water are able to enter the brain.  Unfortuantly they don't prevent narcotics from entering the brain.  brain:  An organ that is pinkish-white in appearance and is located in the skull.  This organ controls almost everything that the body does.    brain grafting:  Brain grafting is the process of taking a thin layer of brain skin from the donor and moving to new host.   brainstem:  This is what the brain had used to be early evolution, but now it only controls our basic functions such as breathing and heart rate.  capillaries:  Tiny blood vessels.  cells:  What all living thing are built from.  central nervous system:  This the brain and spinal cord put together.  Also see:  brain, spinal cord.  cerebellum:  This part of the brain makes sure that all of your body works together.  It also keeps your balance.  cerebral cortex:  This is one of the most important parts of the brain.  It also is produces our thoughts, stores our memories, and plans.  cerebrospinal fluid:  This what the brain floats in.  cerebrum:  The cerebrum is split in to two different sides.  Left and right.  It is located at the front of the head.  choroid plexuses:  These special blood vessels are what produce the cerebrospinal fluid.  cortex:  This is the outer layer of the cerebrum.  cranium:  This is the part of the skull that holds the brain.   diseases:  Illnesses that can be terminal.  electrodes:  They are made out metal and emit electricity, usually  very little.  glucose: This is a combination of sugar and water.  grey matter:  Mainly made from the cell bodies of neurons.  hemisphere:  These are the two different part of the cerebrum.  Almost all of the brain's work is done there.  hormones:  Chemicals that can change the chemical make up of your physical body.  hypothalmus:  This part of the brain is located above the brainstem.  It controls basic drives such as hunger and sex.  medulla:  The medulla is almost right behind the brainstem.  It helps you to digest your food.  mind:  Not just the brain but the actual consciousness that we have.  nerves:  Pathways that the brain uses to send messages to and from different parts of the body.  nervous system:  The whole system of nerves that attach to the spinal cord.  organs:  Important part of the body.  The brain, heart and lungs are examples of organs.  Parkinson's Disease:  This disease causes the victim to have seizures.  pituitary:  The pituitary produces hormones.  pons:  A band of nerve fibre that connect the back the brain to the middle.   skull:  The skull is made up of twenty-eight bones.  It is located above the spinal cord.  It also contains the brain.  spinal cord:  This cord goes down your back.  Almost all nerves in the body are connected to the spinal cord.  thalamus:  The thalamus a sort of relay room.  It gets messages from the lower brain area and sends them to the higher brain.    transplant:  To transplant is to take something from one person and put it into another person.  white matter:  White matter is tissue made from nerve fibres.