The Human Brain

The brain, what is it? The brain is a portion of the central nervous system that is contained within the skull. The brain controls movement, sleep, hunger, thirst and virtually every other vital activity that is necessary for survival. All human emotions – including love, hate, fear, anger, elation, and sadness are controlled by the brain. The brain also receives and interprets countless signals that are sent to it from other parts of the body as well as the external environment. In short, the brain makes us conscious, emotional, and intelligent. The brain is composed of several key structures and areas. Some of these are the Thalamus Hypothalamus, The Endocrine system and the limbic system.

Thalamus

The Thalamus lies underneath the cerebrum and then connects to the brain stem. The thalamus itself consists of two rounded masses of grey tissue lying within the middle of the brain between the two cerebral hemispheres. The thalamus is the main relay station for the incoming sensory signals to the cerebral cortex and for outgoing motor signals from it. All sensory input except smell connects to individual nuclei of the thalamus.

Damage to the thalamus can cause amnesia or Korsakoff’s syndrome or Korsakoff’s psychosis. Korsakoff’s syndrome is a disorder that produces severe and often times permanent amnesia. This can be cause by years of alcoholism and thiamine defiency. Korsakoff’s patient’s often show signs of severe anterograde amnesia, or difficulty learning anything new. Patients may also suffer from retrograde amnesia, which can range from mild to severe and they typically cannot remember recent experiences.

Hypothalamus

The hypothalamus “lies beneath the thalamus on the middle at the base of the brain”. (Encarta.msn, 2006). The hypothalamus regulates or is indirectly involved in the control of many of the body’s vital drives and activities, such as eating, drinking, temperature, regulation, sleep emotional behavior, and sexual activity. It also controls the function of internal body organs by means of the automatic nervous system, as well interacts with the pituitary gland, and helps coordinate activity of the brain stem.

The hypothalamus controls a wide range of functions, such as the “fight or flight” response. Fear and excitement cause signals to the travel to the hypothalamus, which triggers a rapid heartbeat, faster breath, widening of the pupils and increase blood flow. The hypothalamus also maintains blood glucose levels and he body’s water content to regulate, the bodies appetite for food and drinks. Finally, the hypothalamus regulates sleep and sexual behavior.

Damage to the hypothalamus can result from surgery, trauma, degeneration due to old age or disease or a tumor. The results of such damage can be varied and often times depend on the areas of the hypothalamus involved. Some diseases that can be caused are diabetes insipious, sexual abnormalities, psychic disturbances, obesity, anorexia, temperature regulation disorders, sleep disorders, and disruption of normal circadian rhythms.

Endocrine System

The Endocrine System is a group of specialized organ’s and body tissues that produce, store and secret chemical substances known as hormones. Hormones transfer information and instructions from one set of cells to another. Because of these hormones, endocrine organs have a large amount of influence over the body. Some of there jobs include regulating the body’s’ growth and development, controlling the function of various tissues, supporting pregnancy and other reproductive functions and regulating metabolism.

Endocrine organs are often times called ductless glands; this is because they have no ducts connecting them to specific body parts. The hormones that endocrine secrets are release directly into the blood stream. The primary glands that make up the human endocrine system are the hypothalamus, pituitary, thyroid, parathyroid, adrenal, and reproductive glands. The pancreas is also considered a part pf the endocrine system.

“Disorders of the endocrine system are classified in two ways; disturbances in the production and inability of tissue to respond to hormones. Production disorders are divided into hypo function (insufficient activity) and hyperfuction (excess activity).” (Encarta.msn, 2006).Some diseases that can be causes by these disorders are diabetes, hypothyroidism, Addison’s disease; Cushing’s syndrome, thyroxicosis, and aciomegaly gigantism (stimulates production of excessive growth hormones).

Limbic System

The limbic system is a complex set of structures that lie on both sides and underneath the thalamus, just under the cerebrum. The limbic system includes the hypothalamus, the hippocampus, the Amygdala, and other nearby areas. The limbic system is the primarily responsible for the human emotion and the formation of memories.

The hippocampus consists of two “horns” that curve back from the amygdaloidal. What hippocampus appears to do is convert things already in your mind into short term memory. If this is damages, a person cannot build new memories. The amygdaloidal are two almond shaped masses of neurons located on either side of the thalamus at the lower end of the hippocampus. When it is stimulated it can cause aggression, if it is removed or damaged it can cause tameness and a decrease in sexual response. Diseases that can be caused by damage to the limbic system are Alzheimer’s disease, epilepsy, depression, hallucinations and many common emotional, disorders.

The Left Hemisphere of the Brain

The left hemisphere is important for all forms of communication. This can be proven because when there is damage to the left side of the brain there can be serious problems in speaking and difficulty in movement of the mouth, hands, or arms. The left hemisphere processes information sequentially and is described as analytical because it specializes in recognizing parts which make a whole. This hemisphere is capable of recognizing that one stimulus comes before another and verbal perception and generation depends on the awareness of the sequence in which sounds occur.

The Right Hemisphere

The right hemisphere does not appear to be involved in communication however; it does help us to understand words. The right hemisphere specializes in receiving and analyzing information from the outside world. Damage to the right hemisphere may lead to our being unable to tell the difference between melodies or it may make it difficult to identify objects. The right hemisphere unlike the left hemisphere analyzes data simultaneous. The right hemisphere perceives and constructs patterns. It is most effective at visual and spatial processing and it is thought that the right hemisphere processes non-verbal stimuli.

MSN Encarta Premium, the Human Brain. Retrieved February 15, 2006 http://encarta.msn.com/encyclopedia_761555359/Brain.html#p42
MSN Encarta Premium, Endocrine System, Retrieved February 15, 2006 http://encarta.msn.com/encyclopedia_761574274_1/Endocrine_System.html#S1
MSN Encarta Premium, Hypothalamus, Retrieved February 15, 2006 http://encarta.msn.com/encyclopedia_761582440_1/Hypothalamus.html#S1
MSN Encarta Premium, Neurotransmitter, Retrieved February 15, 2006 http://encarta.msn.com/encyclopedia_761586355_1/Neurotransmitter.html#S1
Web UK Online, Structure of the Brain, Retrieved February 16, 2006
http://web.ukonline.co.uk/madeleine.portwood/brain.htm
Carole Wade & Carol Tavris (2006) Psychology, Upper Saddle River NJ Pearson Education Inc References
MSN Encarta Premium, the Human Brain. Retrieved February 15, 2006 http://encarta.msn.com/encyclopedia_761555359/Brain.html#p42
MSN Encarta Premium, Endocrine System, Retrieved February 15, 2006 http://encarta.msn.com/encyclopedia_761574274_1/Endocrine_System.html#S1
MSN Encarta Premium, Hypothalamus, Retrieved February 15, 2006 http://encarta.msn.com/encyclopedia_761582440_1/Hypothalamus.html#S1
MSN Encarta Premium, Neurotransmitter, Retrieved February 15, 2006 http://encarta.msn.com/encyclopedia_761586355_1/Neurotransmitter.html#S1
Web UK Online, Structure of the Brain, Retrieved February 16, 2006
http://web.ukonline.co.uk/madeleine.portwood/brain.htm
Carole Wade & Carol Tavris (2006) Psychology, Upper Saddle River NJ Pearson Education Inc

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