by Brad Norman

Created on: April 10, 2009

The cell is the fundamental unit of life. It's the building block from which every plant, animal, and fungus is built from. This includes human beings.

The human body is composed of trillions of cells which all work together to make the body work the way it should. There are blood cells, hepatic (liver) cells, neurons, skin cells, and countless other types of cells that make up the human body. Different cells are capable of different abilities.When a bunch of cells with the same characteristics group together, it's called a "tissue".

Let's look at a few of the most important types of cells.

Blood cells. These are also known as erythrocytes. Their job is clear: circulate oxygen and other vital molecules throughout the body. This is done by several protein pumps in the cell membrane which helps take molecules on board. Oxygen in held in blood cells by binding it to an iron molecule within the hemoglobin protein. Hemoglobin is also responsible for taking up carbon dioxide from other parts of the body and bringing it to the lungs where it can be exhaled.

Neurons. These are cells of the nervous system. They have specialized receptors and chemicals used for sending signals to other neurons and muscles. These type of cells also have long tail-like structures called axons. These act like wires within you body and are capable of firing an electrical signal throughout your body in a matter of milliseconds. These cells are by far the longest cells in your entire body. There is a neuron in your legs which stretched from the base of your spinal cord all the way to the tip of your big toe. That's a big cell!

Muscle cells. These cells and loaded with proteins called actin and myosin. These proteins are capable of changing shape by burning ATP molecules (a form of cellular energy). When these proteins all change shape in unison, it shortens the length of the cell and thus makes the entire muscle tissue contract. When many of these muscle cells contract at the same time, it produces enough movement to move limbs like your arms and legs.

These are just three types out of the hundreds of specialized cells in your body. There are other cells to help destroy toxins, some for immunity to diseases, and some even respond to light. Each cell, though diverse in their function, all work together perfectly to carry out the tasks we do every day. The loss of even one of these functions could drastically impact human life, and thus emphasizes the importance of the cell.

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