The eyes A close up of a young person's eyes. The eyes are responsible for four-fifths of all the information our brain receives. Here you can find out a bit more about how they work, common problems that affect vision and the work Sightsavers does to treat and prevent avoidable blindness. You can also find out more about the people whose lives have been changed thanks to donations from people like you. How do eyes work? (click image to see enlarged version or click here for text alternative) Graphic of an eye with information about its different parts The images we see are made up of light reflected from the objects we look at. This light enters the eye through the cornea. Because this part of the eye is curved, it bends the light, creating an upside down image on the retina (this is eventually put the right way up by the brain). The retina is a complex part of the eye, but only the very back of it is light sensitive. This part of the retina has roughly the area of a 10p coin, and is packed with photosensitive cells called rods and cones. Cones are the cells responsible for daylight vision. There are three kinds – each responding to a different wavelength of light: red, green and blue. The cones allow us to see images in colour and detail. Rods are responsible for night vision. They are sensitive to light but not to colour. In darkness, the cones do not function at all. How do we see an image? The lens focuses the image. It can do this because it is adjustable – using muscles to change shape and help us focus on objects at different distances. The automatic focusing of the lens is a reflex response and is not controlled by the brain. Once the image is clearly focused on the sensitive part of the retina, energy in the light that makes up that image creates an electrical signal. Nerve impulses can then carry information about that image to the brain through the optic nerve.

Red blood cells, which form one of the major constituents of blood, are characterized by the absence of nuclei, hence they are unable to undergo cellular division or generate new erythrocytes from old ones. This eventually leads to cell disintegration, which typically occurs 4 months after the fully developed red blood cells have been in circulation within the bloodstream. During the degeneration of the red blood cells, some components of the hemoglobin are excreted from the body while other parts are conserved.

Hemoglobin is the protein molecule in red blood cells that carries oxygen from the lungs to the body's tissues and returns carbon dioxide from the tissues back to the lungs. Hemoglobin is made up of four protein molecules (globulin chains) that are connected together.

Neonatal resuscitation skills are essential for all health care providers who are involved in the delivery of newborns. The transition from fetus to newborn requires intervention by a skilled individual or team in approximately 10% of all deliveries. This figure is concerning because 81% of all babies in the United States are born in nonteaching, nonaffiliated level I or II hospitals. In such hospitals, the volume of delivery service may not be perceived as sufficient economic justification for the continuous in-hospital presence of personnel with high-risk delivery room experience, as recommended by the American Academy of Pediatrics (AAP) and the American College of Obstetricians and Gynecologists (ACOG). [1] Perinatal asphyxia and extreme prematurity are the 2 complications of pregnancy that most frequently necessitate complex resuscitation by skilled personnel. However, only 60% of asphyxiated newborns can be predicted ante partum. The remaining newborns are not identified until the time of birth. Additionally, approximately 80% of low-birth-weight infants require resuscitation and stabilization at delivery. Nearly one half of newborn deaths (many of which involve extremely premature infants) occur during the first 24 hours after birth. Many of these early deaths also have a component of asphyxia or respiratory depression as an etiology. For the surviving infants, effective management of asphyxia in the first few minutes of life may influence long-term outcome. Even though prenatal care can identify many potential fetal difficulties ante partum, allowing maternal transfer to the referral center for care, many women who experience preterm labor are not identified prospectively and therefore are not appropriately transferred to a tertiary perinatal center. Consequently, many deliveries of extremely premature infants occur in smaller hospitals. For this reason, all personnel involved in delivery room care of the newborn should be trained adequately in all aspects of neonatal resuscitation. Additionally, equipment that is appropriately sized to resuscitate infants of all gestational ages should be available in all delivering institutions, even if the institution does not care for preterm or intensive care infants. Along with the necessary skills, the practitioner should approach any resuscitation with a good comprehension of transitional physiology and adaptation, as well as an understanding of the infant's response to resuscitation. Resuscitation involves much more than possessing an ordered list of technical skills and having a resuscitation team; it requires excellent assessment skills and a grounded understanding of physiology.

Sex easily falls to the wayside during pregnancy. Research shows that good sex has a significant impact upon not just the relationship, but also a woman’s ability to have an easeful and even joyful birth. Unfortunately, sex during pregnancy can be quite complicated for a variety of physical and emotional reasons. This week’s video will outline how to overcome these hurdles and make sure you continue to enjoy the wonders of sex as you embark on the first steps of parenthood.

Weight loss is the most effective nonpharmacologic measure to decrease blood pressure in overweight individuals. Weight loss with other nonpharmacologic measures can prevent or delay the onset of hypertension and reduce the overall risk of cardiovascular events in such patients. In some patients with established hypertension, lifestyle changes alone may control their blood pressure.

Cardiovascular disease (CVD) is a general term that describes a disease of the heart or blood vessels. Blood flow to the heart, brain or body can be reduced as the result of a blood clot (thrombosis), or by a build-up of fatty deposits inside an artery that cause the artery to harden and narrow (atherosclerosis).

The average human digestive tract is home to as many as 1,000 species of microorganisms. Most of them are harmless -- or even helpful -- under normal circumstances. But when something upsets the balance of these organisms in your gut, otherwise harmless bacteria can grow out of control and make you sick. One of the worst offenders is a bacterium called Clostridium difficile(C. difficile, or C. diff). As the bacteria overgrow they release toxins that attack the lining of the intestines, causing a condition called Clostridium difficilecolitis.

Herpangina is a common childhood illness caused by a virus. It is characterized by small, blister-like ulcers on the roof of the mouth and in the back of the throat. The infection may also cause a sudden fever, sore throat, headache, and neck pain.

Hemolytic-uremic syndrome (or haemolytic-uraemic syndrome), abbreviated HUS, is a disease characterized by hemolytic anemia (anemia caused by destruction of red blood cells), acute kidney failure (uremia), and a low platelet count (thrombocytopenia).

The Hydatid cyst in the video weighed approximately 300gms and had a diameter of 9 cms .

TransMedics’ proprietary Organ Care System (OCS) is the first commercial and portable warm blood perfusion organ transport system. With the OCS, doctors are able to perform “living organ transplants,” where organs are kept warm and functioning in a controlled environment from the time they are recovered to the moment they are placed in the recipient’s body.

A nephron (from Greek νεφρός (nephros) meaning "kidney") is the basic structural and functional unit of the kidney. Its chief function is to regulate the concentration of water and soluble substances like sodium salts by filtering the blood, reabsorbing what is needed and excreting the rest as urine.

Brain Tumor and Skull-Base Surgery

Red blood cells, most white blood cells, and platelets are produced in the bone marrow, the soft fatty tissue inside bone cavities. Two types of white blood cells, T and B cells (lymphocytes), are also produced in the lymph nodes and spleen, and T cells are produced and mature in the thymus gland.

Surgery is an elective procedure done in people who have had extensive testing to decide if they are potential candidates. The following criteria are considered when determining if a person may be a good candidate for surgery. Person has failed adequate trials of two first-line seizure medicines (ones that are commonly effective in controlling the type of seizures the person is experiencing) and one combination of at least two drugs. A trial of a medication is considered adequate when it has been increased gradually to the maximum dosage that does not cause serious side effects. If the person has frequent seizures, any improvement will be obvious after a short time. If the seizures generally occur far apart, however, it may take months to determine whether a medication is helping. At some epilepsy centers, patients are offered additional conventional or experimental medications before surgery is considered. But research suggests that each time a trial of medication fails to control a person's seizures, it becomes less likely that a different medicine or combination will be successful. Since uncontrolled seizures present serious physical risks and social and psychological consequences, the trend these days is to proceed with surgery much sooner than in the past if it seems appropriate for that person.

Bacterial vaginosis is a type of vaginal inflammation caused by the overgrowth of bacteria naturally found in the vagina, which upsets the natural balance. Women in their reproductive years are most likely to get bacterial vaginosis, but it can affect women of any age. The cause isn't completely understood, but certain activities, such as unprotected sex or frequent douching, increase your risk.

The dental implant, usually a cylindrical and/or tapered post made of titanium, is placed surgically into the jawbone. As you heal, your implant will osseointegrate, or fuse with, your natural jawbone, with the two growing together to form a strong and long-lasting foundation for your replacement teeth.

Gitelman syndrome is a kidney disorder that causes an imbalance of charged atoms (ions) in the body, including ions of potassium, magnesium, and calcium. The signs and symptoms of Gitelman syndrome usually appear in late childhood or adolescence. Common features of this condition include painful muscle spasms (tetany), muscle weakness or cramping, dizziness, and salt craving. Also common is a tingling or prickly sensation in the skin (paresthesias), most often affecting the face. Some individuals with Gitelman syndrome experience excessive tiredness (fatigue), low blood pressure, and a painful joint condition called chondrocalcinosis. Studies suggest that Gitelman syndrome may also increase the risk of a potentially dangerous abnormal heart rhythm called ventricular arrhythmia. The signs and symptoms of Gitelman syndrome vary widely, even among affected members of the same family. Most people with this condition have relatively mild symptoms, although affected individuals with severe muscle cramping, paralysis, and slow growth have been reported.

Hereditary hemochromatosis (he-moe-kroe-muh-TOE-sis) causes your body to absorb too much iron from the food you eat. Excess iron is stored in your organs, especially your liver, heart and pancreas. Too much iron can lead to life-threatening conditions, such as liver disease, heart problems and diabetes.