Updated: Oct 18
Tissues A tissue is a group of similar or dissimilar cells that perform or help to perform a common function and have a common origin. Tissues are the basic building blocks of organs and organ systems. Types of tissues: There are four main types of tissues: epithelial tissue, connective tissue, muscle tissue, and nervous tissue. Epithelial tissue: Epithelial tissue lines the surfaces of the body and covers its organs and glands. It is also found in many internal organs, such as the lining of the digestive and respiratory tracts. Epithelial tissue is responsible for a variety of functions, including: Protection: Epithelial tissue protects the body from the environment and from harmful substances. Absorption: Epithelial tissue absorbs nutrients and other substances from the environment. Secretion: Epithelial tissue secretes hormones, enzymes, and other substances. Transport: Epithelial tissue transports gases, nutrients, and waste products throughout the body. Connective tissue: Connective tissue supports, connects, and protects the other tissues of the body. It is found in all parts of the body, including the skin, bones, muscles, and blood vessels. Connective tissue is made up of cells and a matrix, which is a material that surrounds the cells. The matrix can be loose and fluid-filled, or it can be dense and fibrous. There are many different types of connective tissue, including: Loose connective tissue: Loose connective tissue is found beneath the skin and around organs. It contains many cells and a loose matrix. Dense connective tissue: Dense connective tissue is found in tendons and ligaments. It contains fewer cells and a denser matrix. Cartilage: Cartilage is a supportive tissue found in the joints, ears, and nose. It is made up of cells and a matrix that is rich in collagen. Bone: Bone is a hard, supportive tissue that makes up the skeleton. It is made up of cells and a matrix that is rich in calcium and phosphate. Blood: Blood is a fluid connective tissue that circulates throughout the body. It carries oxygen, nutrients, and waste products to and from the cells. Muscle tissue: Muscle tissue is responsible for movement. It is found in the muscles of the body, including the skeletal muscles, smooth muscles, and cardiac muscle. Skeletal muscle: Skeletal muscle is attached to bones and is responsible for voluntary movement. Smooth muscle: Smooth muscle is found in the walls of blood vessels and internal organs. It is responsible for involuntary movement. Cardiac muscle: Cardiac muscle is found in the heart and is responsible for pumping blood throughout the body. Nervous tissue: Nervous tissue is responsible for the transmission of nerve impulses throughout the body. It is made up of neurons, which are specialized cells that can conduct electrical signals. Nervous tissue is found in the brain, spinal cord, and nerves. Functions of tissues: Tissues work together to perform the many functions of the body. For example, epithelial tissue and connective tissue work together to protect the body from the environment. Muscle tissue and connective tissue work together to allow movement. And nervous tissue works together with all the other tissues to coordinate the body's activities. High school notes on tissues: In high school biology, students learn about the four main types of tissues and their functions. They also learn about some of the specific tissues that are found in different parts of the body. For example, students learn about the epithelial tissue that lines the digestive tract, the connective tissue that makes up the bones and joints, and the muscle tissue that allows us to move. Here are some additional notes on tissues that may be helpful for high school students: Tissues are organized into organs and organ systems. Organs are groups of tissues that work together to perform a specific function. For example, the heart is an organ that is made up of cardiac muscle tissue and connective tissue. Organ systems are groups of organs that work together to perform a major function of the body. For example, the circulatory system is made up of the heart, blood vessels, and blood. Tissues are constantly being renewed. When cells die or are damaged, new cells are produced to replace them. This process is called cell division. Tissues can be damaged by disease, injury, or exposure to harmful substances. When tissues are damaged, the body may try to repair the damage. However, if the damage is too severe, the tissues may be permanently damaged or destroyed. Conclusion: Tissues are the basic building blocks of the body. They are responsible for all of the body's functions, from protecting the body from the environment to allowing us to move and think.