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All the Cells in the Human Body 1

Last updated almost 5 years ago
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Specialized Cells of the Human Body- Article with stop and think comprehension questions
RTI Tier 1 Students (On or above level)
All The Cells in the Human Body

There are trillions of cells in the human body. Cells make up tissues, and tissues make up organs. Organs form organ systems, and organ systems work together to keep an organism alive.
There are hundreds of different types of cells in the body and the structure of a cell is perfectly suited for the role it performs. Cells of the digestive system, for instance, have a different function from cells of the skeletal system.
1

Stop and Think: Why does the body need multiple types of cells?

Bone Cells

Bones are a type of connective tissue and a major part of the skeletal system. They are formed by bone cells, and are a combination of collagen and calcium minerals. There are three main types of bone cells in the body. These bone cells help aid in the formation of bone and help maintain calcium balance.
1

Stop and Think: What is the purpose of bone cells?

Blood Cells

From transporting oxygen throughout the body to fighting infection, cells of the blood are vital to life. The three major types of cells in the blood are red blood cells, white blood cells and platelets. Red blood cells determine blood type and are also responsible for transporting oxygen to other cells. White blood cells are immune system cells that destroy disease-causing organisms, and provide protection. When blood vessels break, platelets, which are produced by bone marrow, help to clot the blood and prevent too much blood loss.
1

Stop and Think: What are the three jobs of the blood cells?

Fat Cells

Fat cells contain droplets of stored fat that can be used for energy. When fat is being stored, fat cells swell and become round in shape. When fat is being used, these cells shrink in size. Fat cells also produce hormones that influence blood pressure regulation, fat storage and use, blood clotting and cell signaling.
1

Stop and Think: How can fat cells change?

Skin Cells

The skin is composed of a series of layers. The outermost layer is called epidermis, and is supported by a layer of connective tissue called dermis. The outermost layer of the skin is composed of flat epithelial cells that are closely packed together. The skin protects the internal structures of the body from damage and prevents dehydration. It also acts as a barrier against germs, stores fat and produces vitamins and hormones.
1

Stop and Think: What is the major function of the skin cells?

Muscle Cells

Muscle cells form muscle tissue, which is important for moving the body. There are three types of muscle cells: skeletal muscles, cardiac muscles, and smooth muscles. Skeletal muscle tissue, like a tendon, attaches to bones and allows us to move as we please. Cardiac muscle cells form the muscles in the heart, which help the heart contract as it pumps blood. These muscles are involuntary, which means that they move without us telling them to do so. Smooth muscle is also involuntary. It is a type of muscle that forms the walls of many organs, including kidneys, intestines, blood vessels and lung airways.
1

Stop and Think: What is the difference between a skeletal muscle and an involuntary muscle (cardiac & smooth)?

Nerve Cells

Nerve cells are the basic units of the nervous system. Nerves send signals between the brain, the spinal cord and the various body organs through nerve impulses. A neuron consists of two major parts, a cell body and nerve processes. The central cell body contains the neuron's nucleus, associated cytoplasm and organelles. Nerve processes extend from the cell body and are able to create and send signals elsewhere.
1

Stop and Think: Why does a nerve cell need two parts?

Stem Cells

Stem cells are unique cells because they are not specialized for any particular role. However, they have the ability to develop into specialized cells for specific organs or tissues when the need arises. Stem cells are able to divide and replicate many times in order to renew and repair tissue. Scientists are researching ways to take advantage of the renewal properties of stem cells. They use these cells to repair damaged tissue, for organ transplantation and for the treatment of disease.
1

Stop and Think: Why are stem cells unique?

Endothelial Cells

Endothelial cells make up the inner layer of blood vessels, lymphatic vessels and organs including the brain, lungs, skin and heart. Endothelial cells are responsible for the creation of new blood vessels. They also regulate the movement of gases and fluid between the blood and surrounding tissues, and help to regulate blood pressure.
1

Stop and Think: What cellular process do endothelial cells facilitate? How do you know?