Please answer the questions in APA format sixth edition.
Mr. Roberts, a 65-year-old man, tells you that his prostate specific antigen (PSA) test was positive. He asks you to explain what that means for him.
You are asked to speak to a fifth grade health class about health and cigarette smoking. What information would you consider essential?
Discuss why childhood cancer should be viewed as a chronic disease. What factors might contribute to quality of life for childhood cancer survivors, providing opportunities for future research?
How would you differentiate between upper and lower motor neuron injury?
Once again, using the analogy of a cellular society, it is relevant to point out that the overall goal of this cell society is survival of the entire organism and not just the individual cell. Therefore, a balance is maintained between cell birth rate and cell death rate. The cellular control mechanisms that regulate cell birth and cell death are called social controls and require social control genes. These genes (oncogenes and tumor-suppressor genes) control growth-factor-regulated cell division. Mutation of these genes causes tumor formation.
Immunotherapy can be difficult to comprehend because it requires mastery of many concepts involving normal immunity. The three mechanisms that describe the activities of the biologic response modifiers are: (1) direct cytotoxic effects on cancer cells (e.g., interferon), (2) initiation or augmentation of the host’s tumor-immune rejection response, and (3) modification of cancer cell susceptibility to the lytic or tumor-static effects of the immune system.
According to the American Cancer Society, acute lymphocytic leukemia (ALL) is the type of leukemia that most commonly affects children, most often between the ages of 2 and 4 years. Acute myelogenous leukemia (AML) is the second most common form of leukemia in children. AML generally occurs by the age of 2 years and is not often seen in older children until the teenage years. AML is the most common type of acute leukemia in adults. The chronic forms of leukemia are rarely seen in children.
There are three main types of leukemia, including the following:
- Acute lymphocytic leukemia (ALL)
ALL, also called lymphoblastic or lymphoid, accounts for most of the childhood leukemias. In this form of the disease, the lymphocyte cell line is affected. The lymphocytes normally fight infection. With ALL, the bone marrow makes too many of these lymphocytes, and they do not mature correctly. The lymphocytes overproduce, thus crowding out other blood cells. Immature blood cells (blasts) do not work properly to fight infection. Acute leukemia can occur over a short period of days to weeks. Chromosome abnormalities (extra chromosomes and structural changes in the chromosome material) are present in the majority of ALL patients.
- Acute myelogenous leukemia (AML)
AML, also called granulocytic, myelocytic, myeloblastic, or myeloid, accounts for mostly the remainder of the childhood leukemias. AML is a cancer of the blood in which too many granulocytes, a type of white blood cell, are produced in the marrow. The granulocytes normally fight infection. With AML, the bone marrow makes too many of these cells, and they do not mature correctly. The granulocytes overproduce, thus crowding out other blood cells. Immature blood cells (blasts) do not work properly to fight infection. Acute leukemia can occur over a short period of days to weeks. Children with certain genetic syndromes, including Fanconi anemia, Bloom syndrome, Kostmann syndrome, and Down syndrome, are at a higher risk of developing AML than other children.
- Chronic myelogenous leukemia (CML)
CML is uncommon in children. CML is cancer of the blood in which too many granulocytes, a type of white blood cell, are produced in the marrow. The granulocytes normally fight infection. With this disease, the bone marrow makes too many of these cells, and they do not mature correctly. The marrow continues to produce these abnormal cells, which crowd out other healthy blood cells. CML can occur over a period of months or years.
Thibodeau and Patton’s analogy of telephone engineering as a model for explaining the nervous system is a great way to explain this. A telephone engineer first learning about telephone systems begins with the easy concept of a two-telephone system. Only later are more complex systems such as switching systems and satellite relays studied in detail. Likewise, the study of the human nervous system begins with the simplest component, the neuron, and the simplest pathway, the reflex arc.
Students sometimes have difficulty with the concept of tracts within the central nervous system. Again let’s use the telephone system as an analogy and use a telephone cable as a model for explaining nerve impulse conduction. The cable is composed of bundles of wire within an insulating tube. Each wire within the bundle may terminate at a different location, similar to the distribution of a nerve tract from the brain to different points in the body (motor tracts) or from different points in the body to the brain (sensory fiber tracts). Understanding these different nerve tracts can be helpful when trying to determine what part of the brain or spinal cord has been injured following trauma or illness.
Neurotransmitters are the chemicals that allow signal transmission from one neuron to the next across synapses. They are also found at the axon endings of motor neurons, where they stimulate muscle fibers.
Acetylcholine was the first neurotransmitter to be discovered. Acetylcholine has many functions. It is responsible for much of the stimulation of muscles, including the muscles of the gastrointestinal system. It is also found in sensory neurons and in the autonomic nervous system and has a part in rapid eye movement sleep.
The plant poisons curare and hemlock cause paralysis by blocking the acetylcholine receptor sites of muscle cells. The well-known poison botulin works by preventing the vesicles in the axon ending from releasing acetylcholine, causing paralysis. The botulin derivative botox is used by many people to temporarily eliminate wrinkles. On a more serious note, there is a link between acetylcholine and Alzheimer disease; there is something on the order of a 90% loss of acetylcholine in the brains of people suffering from Alzheimer disease.
In 1946, Swedish biologist Ulf von Euler discovered norepinephrine (formerly called noradrenalin). Norepinephrine is strongly associated with bringing our nervous systems into “high alert.” It is prevalent in the sympathetic nervous system, and it increases our heart rate and our blood pressure. Our adrenal glands release it into the blood stream, along with its close relative epinephrine (adrenalin), important for forming memories.
Stress tends to deplete our store of adrenalin, while exercise tends to increase it. Amphetamines work by causing the release of norepinephrine, as well as other neurotransmitters called dopamine and serotonin.
Another relative of norepinephrine and epinephrine is dopamine, discovered to be a neurotransmitter in the 1950s by another Swede, Arvid Carlsson. It is an inhibitory neurotransmitter, meaning that when it finds its way to its receptor sites, it blocks the tendency of that neuron to fire. Dopamine is strongly associated with reward mechanisms in the brain. Drugs like cocaine, opium, heroin, and alcohol increase the levels of dopamine, as does nicotine. If it feels good, dopamine neurons are probably involved!
The severe mental illness schizophrenia has been shown to involve excessive amounts of dopamine in the frontal lobes, and drugs that block dopamine are used to help schizophrenics. On the other hand, too little dopamine in the motor areas of the brain are responsible for Parkinson disease, which involves uncontrollable muscle tremors. It was the same Arvid Carlsson mentioned above who figured out that the precursor to dopamine (called L-dopa) could alleviate some of the symptoms of Parkinson disease. He was awarded the Nobel Prize in 2000.
Recently, it has been noted that low dopamine may be related not only to the unsociability of schizophrenics but also to social anxiety. On the other hand, dopamine has been found to have relatively little to do with the pleasures of eating. That seems to involve chemicals such as endorphins.
In 1950, Eugene Roberts and J. Awapara discovered GABA (gamma aminobutyric acid), which is also usually an inhibitory neurotransmitter. GABA acts like a brake to the excitatory neurotransmitters that lead to anxiety. People with too little GABA tend to suffer from anxiety disorders, and drugs like Valium work by enhancing the effects of GABA. Lots of other drugs influence GABA receptors, including alcohol and barbiturates. If GABA is lacking in certain parts of the brain, epilepsy results.
Glutamate is an excitatory relative of GABA. It is the most common neurotransmitter in the central nervous system—as much as half of all neurons in the brain—and is especially important in regard to memory. Curiously, glutamate is actually toxic to neurons, and an excess will kill them. Sometimes brain damage or a stroke will lead to an excess and end with many more brain cells dying than from the original trauma. Amytrophic lateral sclerosis (ALS), more commonly known as Lou Gehrig disease, results from excessive glutamate production. Many believe it may also be responsible for quite a variety of diseases of the nervous system.
Serotonin is an inhibitory neurotransmitter that has been found to be intimately involved in emotion and mood. Too little serotonin has been shown to lead to depression, problems with anger control, obsessive-compulsive disorder, and suicide. Too little also leads to an increased appetite for carbohydrates (starchy foods) and trouble sleeping, which are also associated with depression and other emotional disorders. It has also been tied to migraines, irritable bowel syndrome, and fibromyalgia.
Prozac and other recent drugs help people with depression by preventing the neurons from “vacuuming” up excess serotonin, so that there is more left floating around in the synapses. It is interesting that a little warm milk before bedtime also increases the levels of serotonin which helps with sleep. Serotonin is a derivative of tryptophan, which is found in milk.
On the other hand, serotonin also plays a role in perception. Hallucinogens such as LSD, mescaline, psilocybin, and ecstasy work by attaching to serotonin receptor sites and thereby blocking transmissions in perceptual pathways.
Endorphin is short for “endogenous morphine.” It is structurally very similar to the opioids (opium, morphine, heroin, etc.) and has similar functions. It is involved in pain reduction and pleasure, and the opioid drugs work by attaching to endorphin receptor sites. It is also the neurotransmitter that allows bears and other animals to hibernate. Consider: Heroin slows heart-rate, respiration, and metabolism in general—exactly what you would need to hibernate.
The capillary walls of the brain serve as a barrier to the movement of selected chemicals and molecules from the blood to the brain tissue. An example of a set of sieves with different gauges of mesh illustrates how some substances are allowed to pass through and others are not, depending on the composition and size of the substance in relation to the mesh size of the sieve.
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||09/18/2014 12:00 am