Neurological System The nervous system is composed of an interlocked system of neurons. The neurons conduct impulses to and from the periphery. They also interconnect with each other to deliver impulses to the various parts of the brain. Neurons generate and conduct electrical impulses by selectively changing the electrical gradient of their membrane and releasing neurotransmitters. Neurotransmitters may be inhibitory or excitatory. Through time, as new skills are adapted or new information is learned, new circuits are formed. With the repetition of learned information, the new circuits undergo myelination. This enables the neurons to conduct impulses faster. The ability of the nervous system to make or break new circuits is responsible for functions of the mind. (McCance & Huether, 2010)

Visual problems can be either congenital or acquired. The most common visual disorders are errors of refraction, strabismus, cataract and retinopathies. Patients with errors of refraction can either be hypermetropic, myopic or astigmatic. Hypermetropia and myopia occur because of an alteration in the axial length of the eyeball, change in the lens or cornea curvatures or due to a displacement of the lens. Hypermetropia is treated with a convex lens whereas a concave lens is used to treat myopia. Astigmatism occurs due a change in the curvature meridian of the cornea or lens, for example in keratoconus, cataract or lenticonus. . This condition is treated with a hard contact lens, or cylindrical or spherocylindrical lenses. All refractive errors can lead to strabismus, which is treated by correcting the underlying error or through surgery. Symptoms of refractive errors and strabismus are similar; they include: eyeaches, headaches, difficulty concentrating and blurred vision. Strabismus may also present with an intermittent squint, that may not be immediately apparent. (Riordan-Eva & Cunningham, 2011)

Cataracts are most commonly because of age related degenerative changes in the lens. It can however also occur due to trauma, drugs, metabolic disorders, or as a part of other congenital syndromes, such as Down's. In the initial phase of the disease, patients usually experience...

They also complain of glare, diplopia and colored halos. Treatment of cataract essentially consists of surgical removal. However, non-surgical measures are used until surgery, such as use of spectacles, dark glasses to reduce glare, and use of mydriatics to improve vision. (Riordan-Eva & Cunningham, 2011)
Retinopathies occur as a complication of prematurity, diabetes and hypertension. Symptoms are related to impairment of vision which may be either sudden or gradual. Premature infants exposed to oxygen therapy need to be screened. The definitive treatment is only with the appropriate management of the underlying cause. (Riordan-Eva & Cunningham, 2011)

3) Chronic pain is generally described to last for greater than 3 months. The exact cause of chronic pain is unknown but an imbalance between neuromodulatory controls is hypothesized. Examples include, back pain, myofascial pain syndromes, chronic post-operative pain, and cancer pain. (McCance & Huether, 2010)

Acute pain, on the other hand, is more sudden and severe in onset, therefore alerting an individual to something more serious. Symptoms of acute pain include those of sympathetic stimulation, for example, tachycardia, hypertension and dilated pupils. Acute pain maybe either somatic or visceral in origin, or maybe referred from another site. Examples of acute pain include aortic dissection and acute pancreatitis. (McCance & Huether, 2010)

4) Genetic epidemiological studies reveal that schizophrenia might be a heritable disorder. There is a higher prevalence of this disease in monozygotic twins and siblings. However, the genetic inheritance differs from mendelian disorders. Schiziophrenia exhibits reduced penetrance. Another hypothesis of its etiology is environmental interference during prenatal neural development, such as infections, nutritional deficiencies. Perinatal complications of birth asphyxia have also shown to be important risk factors. (McCance & Huether, 2010)

5) The development of depression involves both environmental and hormonal…