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Millions of sperms are deposited into the vagina during sexual intercourse. The sperms make their way through the cervix into the uterus and then on to the fallopian tubes. As they swim along this way their numbers decline. Only a few hundred sperm will get close to the egg. During the trip, sperm prepare themselves to meet the egg by subtle alterations of their heads and movement patterns. Once inside the fallopian tube, the sperm attracts the egg by releasing a chemical. The egg is surrounded by a protective covering called the zona pellucida, which allows only one sperm to penetrate it. Once inside the egg, the head of the fertilizing sperm releases its genetic contents, which fuses with the nucleus of the egg. Fertilisation is now complete. Sperm are able to survive for 2-3 days within the female's reproductive tract. The length of the time that a woman's egg can be fertilized by a man's sperm ranges from 12-24 hours.
An undescended testicle (cryptorchidism) is a testicle that hasn't moved into its proper position in the bag of skin hanging below the penis (scrotum) before birth. Usually just one testicle is affected, but about 10 percent of the time both testicles are undescended. An undescended testicle is uncommon in general, but common among baby boys born prematurely. The vast majority of the time, the undescended testicle moves into the proper position on its own, within the first few months of life. If your son has an undescended testicle that doesn't correct itself, surgery can relocate the testicle into the scrotum.
If the artery were severed, blood would flow out unimpeded, although the artery wall would contract in an effort to stop the bleeding. After losing >30% of one's blood volume blood pressure would start dropping, and with less pressure the rate of bleeding would go down. At this stage if the blood loss wasn't replaced the person could die. Losing halve to two thirds of one's blood volume is considered to be fatal even if later on blood transfusion is attempted. One's total blood volume at 70ml/kg is estimated to be between 5 to 7 liters, so that makes a blood loss of between 2,5 to 4,7 L.
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.
When oral medications do not relieve knee pain, but you're not to the point of pursuing knee surgery, one of the following injections or procedures may help. Hyaluronic acid supplements – Although not technically medications, these substances are injected into knee joints to supplement naturally occurring hyaluronic acid. In healthy joints hyaluronic acid acts as a shock absorber and lubricant, allowing joints to move smoothly over each other. However, the acid appears to break down in people with osteoarthritis. Injecting it into a joint may lessen pain and inflammation. The injections are given weekly for three or five weeks, depending on the product (examples are Synvisc and Hyalgan). A small amount of joint fluid is removed first to make room for the hyaluronic acid. Corticosteroid Injections – Doctors sometimes inject corticosteroids directly into the knee joint for quick relief of pain and inflammation. Their benefits may last anywhere from a few days to more than six months. While the injections bring targeted relief to the joint and lack many of the side effects of oral corticosteroid medications, they are not without risks. Repeated knee injections may actually contribute to cartilage breakdown. For that reason your doctor will likely put a limit on the number of injections you can receive. Read a report from the British Medical Journal on corticosteroid injections for knee osteoarthritis. Arthrocentesis – Also called joint fluid aspiration, arthrocentesis is removal of joint fluid through a hollow needle inserted into the joint space of the knee. Although the purpose of removing joint fluid from the knee is usually so that it can be tested in the lab, removing excess fluid can also quickly ease pain and swelling. Often after withdrawing fluid, doctors use the same puncture site where the fluid was removed to inject a corticosteroid preparation and/or anesthetic into the knee joint to further relieve pain and inflammation.
Surgeons at The Children’s Hospital of Philadelphia were the first to perform a bilateral hand transplant on a child. Our research and work in this groundbreaking field of medicine led us to establish the Hand Transplantation Program. Combining the expertise of the Penn Transplant Institute and the Hospital’s Division of Plastic and Reconstructive Surgery and Division of Orthopedics, the program aims to improve quality of life for children who may benefit from this procedure.
A pheochromocytoma (fee-o-kroe-moe-sy-TOE-muh) is a rare, usually noncancerous (benign) tumor that develops in cells in the center of an adrenal gland. You have two adrenal glands, one above each kidney. Your adrenal glands produce hormones that give instructions to virtually every organ and tissue in your body. If you have a pheochromocytoma, an adrenal gland releases hormones that cause persistent or episodic high blood pressure. If left untreated, a pheochromocytoma can result in severe or life-threatening damage to other body systems, especially the cardiovascular system. Most people with a pheochromocytoma are between the ages of 20 and 50, but the tumor can develop at any age. Surgical treatment to remove a pheochromocytoma usually returns blood pressure to normal.
If a patient comes to you with a painful, throbbing, swollen, red face (a ''fat face'), perhaps with fever, trismus and lymphadenitis, he is probably suffering from an acute dental or oral infection, most probably an alveolar abscess. He may have: (1) An alveolar abscess begins as an infection in the bone around a non-vital infected tooth. He has severe pain, which becomes less as pus is released into more superficial tissues and his face starts to swell. After 36 hours of cellulitis he usually has a fluctuant abscess which needs draining. If drainage is delayed, the pus in his abscess discharges spontaneously through a sinus (26-8) in his gum or face, which may become chronic. First, control infection with antibiotics, and then drain the abscess, either by incising it where it is pointing, or by removing the infected tooth, which acts as a cork to prevent the pus escaping, or by doing both these things. If you remove a tooth before you have controlled the infection with antibiotics, and while his face is still severely swollen, you may spread the infection; your task will also be more difficult. (2) A periodontal abscess at the side of a tooth, caused by spread from an infected gum. (3) A pericoronal abscess caused by infection of the gum over the crown of an unerupted and impacted tooth, usually a lower third molar (''an infected wisdom tooth'). Often, an abscess does not form, and the gum round the tooth is merely inflamed.
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.
When you’re depressed, it can feel like you’ll never get out from under a dark shadow. However, even the most severe depression is treatable. So, if your depression is keeping you from living the life you want to, don’t hesitate to seek help. Learning about your depression treatment options will help you decide what approach is right for you. From therapy to medication to healthy lifestyle changes, there are many effective treatments that can help you overcome depression and reclaim your life.