Tonsillitis and Tonsillectomy

Because the tonsils are designed to protect the pharynx from infection, they frequently become inflamed and infected, a condition called acute tonsillitis (ton ́si-lı¯ ́tis). The palatine tonsils are most commonly affected. The tonsils redden and enlarge—in severe cases, to the point that they partially obstruct the pharynx and may cause respiratory distress.

Tonsils may be infected by viruses (such as adenoviruses) or bacteria (most commonly Streptococcus). Streptococcal tonsillitis often results in very red tonsils that have whitish specks (called whitish exudate). The symptoms of tonsillitis include fever, chills, sore throat, and difficulty swallowing. Bacterial tonsillitis (e.g., “strep throat”) is successfully treated with antibiotics such as penicillin or amoxicillin. If tonsillitis is caused by a virus, measures to relieve the inflammation (such as pain medication and/or gargling) are advised, since standard antibiotics are not effective against viruses.

Persistent or recurrent infections can lead to permanent enlargement of the tonsils and a condition known as chronic tonsillitis.

If medical treatment does not help the chronic tonsillitis, surgical removal of the tonsils (tonsillectomy) may be indicated. Typically, medical guidelines suggest performing a tonsillectomy only if the person has had six to seven tonsillar infections in 1 year, or two to three infections per year for several years running. Research indicates that tonsillectomy does not significantly affect the body’s response to new infections.

source : Human anatomy

Diabetes Mellitus

Diabetes (dı¯-ā -bē ́tez) mellitus (me-lı¯ ́tū s; sweetened with honey) is a metabolic condition marked by inadequate uptake of glucose from the blood. The name “diabetes mellitus” is derived from the phrase “sweet urine” because some of the excess glucose is expelled into the urine, resulting in glycosuria (glucose in the urine). Chronically elevated blood glucose levels damage blood vessels, especially the smaller arterioles.
Because of its damaging effects on the vascular system, diabetes is the leading cause of retinal blindness, kidney failure, and nontraumatic leg amputations in the United States. Diabetes is also associated with increased incidence of heart disease and stroke. Three categories of diabetes mellitus are type 1 diabetes, type 2 diabetes, and gestational diabetes.


Type 1 diabetes, also referred to as insulin-dependent diabetes mellitus (IDDM), is characterized by absent or diminished production and release of insulin by the pancreatic islet cells. This type tends to occur in children and younger individuals, and is not directly associated with obesity. Type 1 diabetes develops in a person who harbors a genetic predisposition, although some kind of triggering event is required to start the process. Often, the trigger is a viral infection; then the process continues as an autoimmune condition in which the beta cells of the pancreatic islets are the primary focus of destruction. When the beta cells are destroyed, no insulin is produced, so blood glucose cannot be taken up and utilized by the body tissues. Treatment of type 1 diabetes requires daily injections of insulin. Newer monitoring instruments allow rapid monitoring of blood glucose, allowing better management of food and insulin. Insulin pumps provide the ability to program insulin delivery as well as manual dosage, greatly improving the treatment and lifestyle of people with IDDM.


Type 2 diabetes, also known as insulin-independent diabetes mellitus
(IIDM), results from either decreased insulin release by the pancreatic beta cells or decreased insulin effectiveness at peripheral tissues. This type of diabetes was previously referred to as adult-onset diabetes because it tended to occur in people over the age of 30. However, type 2 diabetes is now rampant in adolescents and young adults. Obesity plays a major role in the development of type 2 diabetes, and more young people today are considered overweight than ever before. Weight reduction supports the prevention of type 2 diabetes and appears to decrease the symptoms of type 2 diabetes that are already presenting. Most type 2 diabetes patients can be successfully treated with a combination of diet, exercise, and medications that enhance insulin release or increase its sensitivity at the tissue level. In more severe cases, a person with type 2 diabetes must take insulin injections.









Gestational diabetes is seen in some pregnant women, typically in the latter half of the pregnancy. If untreated, gestational diabetes can pose a risk to the fetus as well as increase delivery complications. Most at risk for developing this condition are women who are overweight, African American, Native American, or Hispanic, or those who have a family history of diabetes. While gestational diabetes usually resolves after giving birth, a woman who presents with the condition has a 20–50% chance of developing type 2 diabetes within 10 years.


Until recently, there was no cure for diabetes, but in the past few years pancreas transplants have helped individuals with severe cases of diabetes. Pancreas transplants have several drawbacks, however:
They require major surgery, there is a long donor waiting list, and many complications can arise due to the surgery, either from potential rejection of the transplanted organ or the toxic effects of the necessary immunosuppressant antirejection drugs. Recently, a less invasive surgery, called an islet cell transplant, has been developed.
In this procedure, the islet cells are removed from a donor pancreas and purified. Then the cells are injected into a vein that enters the liver. Once in the liver, the islet cells embolize (form big clots) and start producing insulin almost immediately. Islet cell transplants are still very new and have many complications. The process of extracting and purifying the islet cells is complicated and can have a high failure rate; bleeding or major blood clots may occur in the vein where the islet cells are transplanted; and the immunosuppressant drugs that must be taken have serious side effects. Furthermore, recent studies have shown that the efficacy of islet cell transplants is only temporary. Most patients need to resume insulin shots within 2 years of transplantation. Thus, islet cell transplant surgery is reserved for patients who have severe forms of diabetes.

source : Human anatomy

Cataract

A cataract is a clouding of the lens inside the eye which leads to a decrease in vision. It is the most common cause of blindness and is conventionally treated with surgery. Visual loss occurs because opacification of the lens obstructs light from passing and being focused on to the retina at the back of the eye. 

It is most commonly due to biological aging, but there are a wide variety of other causes. Over time, yellow-brown pigment is deposited within the lens and this, together with disruption of the normal architecture of the lens fibers, leads to reduced transmission of light, which in turn leads to visual problems.

Those with cataracts commonly experience diffculty in appreciating colors and changes in contrast, driving, reading, recognizing faces, and coping with glare from bright lights.

Sign and symptoms

Signs and symptoms vary depending on the type of cataract, though there is considerable overlap. People with nuclear sclerotic or brunescent cataracts often notice a reduction of vision. Those with posterior subcapsular cataracts usually complain of glare as their major symptom.

The severity of cataract formation, assuming that no other eye disease is present, is judged primarily by visual acuity test. The appropriateness of surgery depends on a patient's particular functional and visual needs and other risk factors, all of which may vary widely.

Cause

1. Age

Age is the most common cause.  Lens proteins denature and degrade over time and this process is accelerated by diseases such as diabetes and hypertension. With the passage of time, environmental factors including toxins, radiation and UV light have a cumulative effect. These effects are worsened by the loss of protective and restorative mechanisms due to alterations in gene expression and chemical processes within the eye. 

2. Trauma

Blunt trauma causes swelling, thickening and whitening of the lens fibers.

While the swelling normally resolves with time, the white color may remain. In severe blunt trauma, or injuries which penetrate the eye, the capsule in which the lens sits can be damaged. This allows water from other parts of the eye to rapidly enter the lens leading to swelling and then whitening, obstructing light from reaching the retina at the back of the eye. Following electrical injuries, cataracts may develop in 0.7 to 8%.

######### Autism #########

               Autism is a disorder of neural development characterized by impaired social interaction and verbal and non-verbal communication, and by restricted repetitive or stereotyped behavior. The diagnostic criteria require that symptoms become apparent before a child is three years old. Autism affects information processing in the brain by altering how nerve cells and their synapses connect and organize; how this occurs is not well understood.  It is one of three recognized disorders in the autism spectrum (ASDs), the other two being Asperger syndrome, which lacks delays in cognitive development and language, and pervasive developmental disorder, not otherwise specified (commonly abbreviated as PDD-NOS), which is diagnosed when the full set of criteria for autism or Asperger syndrome are not met.

Autism has a strong genetic basis, although the genetics of autism are complex and it is unclear whether ASD is explained more by rare mutations, or by rare combinations of common genetic variants. In rare cases, autism is strongly associated with agents that cause birth defects. Controversies surround other proposed environmental causes, such as heavy metals, pesticides or childhood vaccines;  the vaccine hypotheses are biologically implausible and lack convincing scientific evidence. The prevalence of autism is about 1–2 per 1,000 people worldwide, and it occurs about four times more often in boys than girls. The Centers for Disease Control and Prevention (CDC) report 1.5% of children in the United States (one in 68) are diagnosed with ASD as of 2014, a 30% increase from one in 88 in 2012. The number of people diagnosed with autism has been increasing dramatically since the 1980s, partly due to changes in diagnostic practice and government-subsidized financial incentives for named diagnoses; the question of whether actual prevalence has increased is unresolved.
Parents usually notice signs in the first two years of their child's life.  The signs usually develop gradually, but some autistic children first develop more normally and then regress.Early behavioral, cognitive, or speech interventions can help autistic children gain self-care, social, and communication skills. Although there is no known cure,  there have been reported cases of children who recovered.  Not many children with autism live independently after reaching adulthood, though some become successful.  An autistic culture has developed, with some individuals seeking a cure and others believing autism should be accepted as a difference and not treated as a disorder.


characteristic

Autism is a highly variable neurodevelopmental disorder that first appears during infancy or childhood, and generally follows a steady course without remission.  Overt symptoms gradually begin after the age of six months, become established by age two or three years, and tend to continue through adulthood, although often in more muted form. It is distinguished not by a single symptom, but by a characteristic triad of symptoms:
impairments in social interaction; impairments in communication; and restricted interests and repetitive behavior. Other aspects, such as atypical eating, are also common but are not essential for diagnosis. Autism's individual symptoms occur in the general population and appear not to associate highly, without a sharp line separating pathologically severe from common traits.

Causes 


It has long been presumed that there is a common cause at the genetic, cognitive, and neural levels for autism's characteristic triad of symptoms.
However, there is increasing suspicion that autism is instead a complex disorder whose core aspects have distinct causes the often co-occur.

Autism has a strong genetic basis, although the genetics of autism are complex and it is unclear whether ASD is explained more by rare mutations with major effects, or by rare multigene interactions of common genetic variants.  Complexity arises due to interactions among multiple genes, the environment, and epigenetic factors which do not change DNA but are heritable and influence gene expression. Studies of twins suggest that heritability is 0.7 for autism and as high as 0.9 for ASD, and siblings of those with autism are about 25 times more likely to be autistic than the general population. However, most of the mutations that increase autism risk have not been identified. Typically, autism cannot be traced to a Mendelian (single-gene) mutation or to a single chromosome abnormality, and none of the genetic syndromes associated with ASDs have been shown to selectively cause ASD. Numerous candidate genes have been located, with only small effects attributable to any particular gene. The large number of autistic individuals with unaffected family members may result from copy number variations—spontaneous deletions or duplications in genetic material during meiosis.  Hence, a substantial fraction of autism cases may be traceable to genetic causes that are highly heritable but not inherited: that is, the mutation that causes the autism is not present in the parental genome

The cells the basic unit of structure and function

Cells are the structural and functional units of all organisms, including humans. An adult human body contains about 75 trillion cells. Most cells are composed of characteristic parts that work together to allow them to perform specific body functions.

There are approximately 200 different types of cells in the human body, but all of them share certain common characteristics:

■ All cells perform the general housekeeping functions necessary to sustain life. Each cell must obtain nutrients and other materials essential for survival from its surrounding fluids. Recall from chapter 1 that the total of all the chemical reactions that occur in cells is called metabolism.
■ Cells must dispose of the wastes they produce. If a cell didn’t remove its waste products, this waste would build up in the cell and lead to its death.
■ The shape and integrity of a cell is maintained by both its internal contents and its surrounding membrane.
■ Most cells are capable of undergoing cell division to make more cells of the same type.





The small size of cells is the greatest obstacle to determining their nature. Cells were discovered after microscopes were invented, and high-magnification microscopes are required to see the smallest human body cells. The dimensional unit often used to measure cell size is the micrometer (μm). One micrometer is equal to 1/10,000 of a centimeter (about 1/125,000 of an inch). For example, a red blood cell has a diameter of about 7–8 μm, whereas one of the largest human cells, an oocyte, has a diameter of about 120 μm.
 compares the size of the smallest unit of structure in the human body (an atom) to various cell types as well as to other macroscopic structures, such as an ostrich egg and a human.