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What is Hematology?

"Hematology" comes from the Greek words haima, meaning blood, and logos, meaning study or science. So, hematology is the science of blood.

Blood is very different from other body tissue. Your blood is made of a solid and a liquid portion. The liquid portion is called plasma. The solid portion is comprised of cells.

Cells are the basic units of life. All living organisms are made of one or many cells. Unicellular organisms like bacteria are made of just one cell. Multicellular organisms, like plants and animals, are made of more than one cell. The human body has over 75 trillion cells!

Cells are so small they must be studied under a microscope to be seen. Bacteria are prokaryotic cells that have no nucleus. Most other living things are made of eukaryotic cells, which have a nucleus and organelles. Organelles are organized structures found in or on cells. The nucleus, the largest organelle, contains chromosomes and stores all the genetic information for the cell. Other organelles make proteins, produce energy, or store wastes. Most organelles are surrounded by membranes that let some substances into the cell while keeping others out. Each cell has a cytoskeleton that gives it shape and may help it move. The cell's cytoplasm (cytosol) surrounds the nucleus and organelles. The entire cell is surrounded by a plasma membrane, which works like the organelle membranes, letting some substances in and keeping others out. The ability to select what comes into the cell is known as being semi-permeable.

Most cells share these basic common characteristics, but in multicellular organisms (like people) each cell also performs a specialized function. Your blood cells are very specialized. Blood is the only tissue made of cells that do not stick together. Other tissues like muscle, skeleton, and nerves are made of cells that join together to work together as a tissue. Blood cells, on the other hand, are designed to float seperately throughout your body inside vessels called arteries and veins. Some blood cells can carry oxygen from your lungs to your tissues. Some are able to fight infection, while others can repair the arteries and veins they travel through. There are three main categories of blood cells: white blood cells, red blood cells, and platelets. Each has a particular job in your blood.

When your blood cells aren’t doing their jobs correctly, it can make you sick. There are many different problems that can occur to make your blood cells perform poorly. A person who studies hematology can recognize what type of problem there is with the sick blood cells and why it is happening.

by Clark, Leslie A. last modified Feb 23, 2012 08:36 AM