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.

Diseases and Disorders of the Nails

It then spreads down the bundle of his and then purkinje fibres to cause ventricular contraction. So when viewing the heart from the front, the direction of depolarisation is 11 o'clock to 5 o'clock. The general direction of depolarisation is known as the cardiac axis.

Blepharitis is an inflammation of the eyelids in which they become red, irritated and itchy and dandruff-like scales form on the eyelashes. It is a common eye disorder caused by either bacteria or a skin condition, such as dandruff of the scalp or acne rosacea. It affects people of all ages. Although uncomfortable, blepharitis is not contagious and generally does not cause any permanent damage to eyesight.

Blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium. As the atrium contracts, blood flows from your right atrium into your right ventricle through the open tricuspid valve.

Nephrotic syndrome is a kidney disorder that causes your body to excrete too much protein in your urine. Nephrotic syndrome is usually caused by damage to the clusters of small blood vessels in your kidneys that filter waste and excess water from your blood. Nephrotic syndrome causes swelling (edema), particularly in your feet and ankles, and increases the risk of other health problems. Treatment for nephrotic syndrome includes treating the underlying condition that's causing it and taking medications. Nephrotic syndrome can increase your risk of infections and blood clots. Your doctor may recommend medications and dietary changes to prevent these and other complications of nephrotic syndrome.

Post-streptococcal GN is a form of glomerulonephritis. It is caused by an infection with a type of streptococcus bacteria. The infection does not occur in the kidneys, but in a different part of the body, such as the skin or throat. The strep bacterial infection causes the tiny blood vessels in the filtering units of the kidneys (glomeruli) to become inflamed. This makes the kidneys less able to filter the urine. Post-streptococcal GN is uncommon today because infections that can lead to the disorder are commonly treated with antibiotics. The disorder may develop 1 to 2 weeks after an untreated throat infection, or 3 to 4 weeks after a skin infection. It may occur in people of any age, but it most often occurs in children ages 6 through 10. Although skin and throat infections are common in children, post-streptococcal GN is a rare complication of these infections. Risk factors include: Strep throat Streptococcal skin infections (such as impetigo)

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.

A glucagonoma is a rare tumor of the alpha cells of the pancreas that results in the overproduction of the hormone glucagon. Alpha cell tumors are commonly associated with glucagonoma syndrome, though similar symptoms are present in cases of pseudoglucagonoma syndrome in the absence of a glucagon-secreting tumor.

There are 3 major parts of the respiratory system: the airway, the lungs, and the muscles of respiration. The airway, which includes the nose, mouth, pharynx, larynx, trachea, bronchi, and bronchioles, carries air between the lungs and the body's exterior.

-Almost all the cases of occupational transmission of HIV have been due to transmission via exposure to blood and certain body fluids. The body fluids wherein standard precautions have been recommended include semen, vaginal secretions, and any other body fluid containing visible blood. Other standard precautions, according to the Center for Disease Control and Prevention (CDC), also apply to cerebrospinal, peritoneal, pleural, pericardia!, synovial fluid, or any other tissue, even though the epidemiologic data regarding the risk of HIV transmission from these fluids is insufficient. Standard precautions do not apply to urine, sweat, tears, sputum, vomitus, and nasal secretions or feces, as long as there is no gross visible blood. The occupational transmission of HIV has never been documented from the above sources.

fingerprints and sweat glands

-Traumatic amputation of a body part requires rapid transport of the appendage, which should be wrapped in a saline-moistened gauze, placed in a plastic bag, and transported in a container filled with ice mixed with either saline or sterile water to best preserve the body part and attempt replantation.

American Cancer Society release new breast cancer screening guidelines

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.

Bipolar disorder, also known as manic-depressive illness, is a brain disorder that causes unusual shifts in mood, energy, activity levels, and the ability to carry out day-to-day tasks. There are four basic types of bipolar disorder; all of them involve clear changes in mood, energy, and activity levels.

Sliced Fingertip Makeup Tutorial

How to Grow a New Fingertip

Overbite is a type or malocclusion or an overjet. A lot of people don’t realize that they have an overbite, as they believe their condition is not serious enough to obtain dental attention. This could also for the reason that other cases of overbites are so minor to be noticeable. However, others have serious overbite condition that can make the person’s top jaw look much larger or the bottom jaw significantly smaller. But one thing to remember, overbite can actually cause some dental problems. This condition can change the structure of your face and affect the way you talk. The most popular form of overbite correction is orthodontic treatment. Your dentist will fix the overbite with the help of rubber bands and dental braces to pull the upper teeth back. Tooth extraction may be suggested if overcrowding complicates the overbite so as to provide room for your front teeth. In extreme conditions, overbite surgery may be needed to place your jaw backwards or forwards. Furthermore, if severe overbite is not corrected during adulthood, the teeth may continue to shift and trigger dental issues such as gum disease.

The pituitary is a small gland found inside the skull just below the brain and above the nasal passages, which are above the fleshy back part of the roof of the mouth (known as the soft palate). The pituitary sits in a tiny bony space called the sella turcica. The nerves that connect the eyes to the brain, called the optic nerves, pass close by it.