Top videos
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.
Blood type (or blood group) is determined, in part, by the ABO blood group antigens present on red blood cells. A blood type (also called a blood group) is a classification of blood based on the presence or absence of inherited antigenic substances on the surface of red blood cells (RBCs).
A ventricular septal defect (VSD) is an opening or hole in the wall that separates the two lower chambers of the heart. This wall is called the ventricular septum. The hole causes oxygen-rich blood to leak from the left side of the heart to the right side. This causes extra work for the right side of the heart, since more blood than necessary is flowing through the right ventricle to the lungs. The hole is usually closed with surgery. However, in certain situations, your child's cardiologist and surgeon may think it is best to close the hole with a special device. This procedure is done in the heart catheterization lab.
Cancer, also called malignancy, is an abnormal growth of cells. There are more than 100 types of cancer, including breast cancer, skin cancer, lung cancer, colon cancer, prostate cancer, and lymphoma. Symptoms vary depending on the type. Cancer treatment may include chemotherapy, radiation, and/or surgery.
Cells may have slender extensions of the cell membrane to form cilia or the smaller extensions called microvilli. The microscopic microvilli effectively increase the surface area of the cell and are useful for absorption and secretion functions. A dramatic example is the human small intestine. The tissue has small fingerlike extensions called villi which are collections of cells, and those cells have many microvilli to even further increase the available surface area for the digestion process. According to Audesirk & Audesirk, this can give an effective surface area of about 250 square meters for absorption.
Cardiac cath is performed to find out if you have disease of the heart muscle, valves or coronary (heart) arteries. During the procedure, the pressure and blood flow in your heart can be measured. Coronary angiography is done during cardiac catheterization.
Most people have general anesthesia right before surgery. This means you will be asleep and pain-free. Other kinds of anesthesia, like regional anesthesia or a block, may also be used for this surgery. The tissue to replace your damaged ACL will come from your own body or from a donor. A donor is a person who has died and chose to give all or part of his or her body to help others. Tissue taken from your own body is called an autograft. The two most common places to take tissue from are the knee cap tendon or the hamstring tendon. Your hamstring is the muscle behind your knee. Tissue taken from a donor is called an allograft. The procedure is usually performed with the help of knee arthroscopy. With arthroscopy, a tiny camera is inserted into the knee through a small surgical cut. The camera is connected to a video monitor in the operating room. Your surgeon will use the camera to check the ligaments and other tissues of your knee. Your surgeon will make other small cuts around your knee and insert other medical instruments. Your surgeon will fix any other damage found, and then will replace your ACL by following these steps: The torn ligament will be removed with a shaver or other instruments. If your own tissue is being used to make your new ACL, your surgeon will make a larger cut. Then, the autograft will be removed through this cut. Your surgeon will make tunnels in your bone to bring the new tissue through. This new tissue will be in the same place as your old ACL. Your surgeon will attach the new ligament to the bone with screws or other devices to hold it in place. As it heals, the bone tunnels fill in. This holds the new ligament in place. At the end of the surgery, your surgeon will close your cuts with sutures (stitches) and cover the area with a dressing. You may be able to view pictures after the procedure of what the doctor saw and what was done during the surgery.
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.
The term trisomy is used to describe the presence of three chromosomes, rather than the usual matched pair of chromosomes. For example, if a baby is born with three #21 chromosomes, rather than the usual pair, then the baby would be said to have "trisomy 21." Trisomy 21 is also known as Down syndrome. Other examples of trisomy include syndromes like trisomy 18 and trisomy 13. Again, trisomy 18 or trisomy 13 simply means the child has three copies of the #18 chromosome (or of the #13 chromosome) present in each cell of the body, rather than the usual pair.
The menstrual cycle is the regular natural change that occurs in the female reproductive system like the uterus and ovaries that make pregnancy possible. The cycle is required for the production of ovocytes, and for the preparation of the uterus for pregnancy.