Platelets are cell fragments that are present in blood. They help stop bleeding from skin wounds, ulcers and damaged and diseased organs. In healthy individuals, each milliliter of blood contains between 250,000 and 500,000 platelets, according to the University of Nebraska at Omaha.

Bumps or protruding veins in your upper arms may be a sign of several harmful conditions; however, it could simply be the result of increased exercise. Most people's veins are flat under the skin, but a low body fat percentage can make the veins in your biceps stick out.

Constriction of your blood vessels can occur for many reasons. Most often high blood pressure, or hypertension, is the underlying cause. Unfortunately, there are no symptoms to indicate blood vessel constriction. Left untreated, this can lead to heart disease, heart attack or stroke.

Blood consists of protein-rich liquid and platelets, red blood cells and white blood cells, collectively known as formed blood elements. A complete blood count, or CBC, includes counts of the formed blood elements along with other measurements that help doctors interpret the test results.

Kidneys are complex organs that perform many functions. In addition to filtering blood, they secrete hormones that regulate blood pressure and maturation of red blood cells. Many of the filtration functions also have secondary effects, such as maintaining bone health and controlling the acid-base balance in the body.

Iron is an important mineral that is necessary for a healthy body. Iron helps produce the oxygen-carrying proteins hemoglobin and myoglobin. Persistent low iron levels are more pronounced in menstruating, pregnant or lactating women, vegetarians, long-distance runners, and people with bleeding ulcers.

Supplements or prescription medications that cause the blood vessels to dilate or open are called vasodilators. Vasodilators are used to treat various medical conditions, such as hypertension and coronary artery disease, a heart condition that causes narrowing of the vessels supplying blood to the heart.

Blood flows through your body as a liquid contained within arteries and veins. Under certain conditions, a jellylike blood clot forms inside these blood vessels, causing partial or complete blockage. Some clots go unnoticed, whereas others produce such symptoms as pain, color changes and swelling.

If you are have diabetes, attaining near-normal blood sugars is a goal of therapy. Diet is an essential component of blood sugar management, so it’s important to learn how specific foods affect your numbers.

Histamine is a chemical compound present in the body that is formed and stored in cells called mast cells and basophiles. Histamine plays an important role in the immune system and is part of the body's protective mechanisms against foreign bodies or germs.

Purported to boost the immune system and help ward off disease, wheatgrass is a staple on many health-conscious menus.

Sickle cell disease is a blood disorder affecting approximately 100,000 people in the United States, most of them African-American. It is a complicated disease, and according to a February 2015 study in "Anemia," even some family physicians find it difficult to manage.