define- tissues and tell its type also?
Answers
Tissue Definition:
Tissues are groups of cells that have a similar structure and act together to perform a specific function.
Explanation:
There are four different types of tissues in animals: connective, muscle, nervous, and epithelial.
In plants, tissues are divided into three types: vascular, ground, and epidermal.
Tissue Definition
Tissues are groups of cells that have a similar structure and act together to perform a specific function. The word tissue comes from a form of an old French verb meaning “to weave”. There are four different types of tissues in animals: connective, muscle, nervous, and epithelial. In plants, tissues are divided into three types: vascular, ground, and epidermal. Groups of tissues make up organs in the body such as the brain and heart.
Types of Animal Tissues
Connective
Connective tissue connects or separates groups of other tissues. It is found in between all the other tissues and organs in the body. Connective tissue is made up of cells and ground substance, which is a gel that surrounds cells. Most connective tissue, except for lymph and blood, also contains fibers, which are long, narrow proteins. Fibers can be collagenous, which bind bones to tissues; elastic, which allow organs like the lungs to move; or reticular, which provide physical support to cells. Connective tissue also allows oxygen to diffuse from blood vessels into cells.
Muscle
Muscle tissue comprises all the muscles in the body, and the specialized nature of the tissue is what allows muscles to contract. There are three types of muscle tissue: skeletal muscle, cardiac muscle, and smooth muscle. Skeletal muscle anchors tendons to bones and allows the body to move. Cardiac muscle is found in the heart and contracts to pump blood. Smooth muscle is found in the intestines, where it helps move food through the digestive tract, and it is also found in other organs like blood vessels, the uterus, and the bladder. Skeletal and cardiac muscles are striated; this means that they contain sarcomeres (a unit of muscle tissue) that are arranged in a uniform pattern.
Nervous
Nervous tissue is found in the brain, spinal cord, and peripheral nerves, which are all parts of the nervous system. It is made up of neurons, which are nerve cells, and neuroglia, which are cells that help nerve impulses travel. Nervous tissue is grouped into four types: gray matter and white matter in the brain, and nerves and ganglia in the peripheral nervous system. The main difference between gray and white matter is that axons of the neurons in gray matter are unmyelinated, while white matter is myelinated. Myelin is a white, fatty substance that insulates neurons and is crucial for nervous system functioning.
Peripheral nerve, cross section
This image is a microscopic view of nervous tissue. It is a cross-section of a peripheral nerve.
Epithelial
Epithelial tissue, or epithelium, covers the surfaces of organs including the skin, the trachea, the reproductive tract, and the digestive tract’s inner lining. It creates a barrier that helps protect organs, and it also has roles in absorbing water and nutrients, getting rid of waste, and secreting enzymes or hormones. All of the body’s glands are formed from ingrowths of epithelium. Some common epithelial tissue diseases are skin diseases like eczema and psoriasis, which both cause rashes. When cancer develops from epithelial tissue, it is called a carcinoma. Epithelial cells in the airways are also responsible for asthma, which is characterized by inflammation of the airways that leads to shortness of breath.
Types of Plant Tissues
Vascular
Vascular tissues in plants transport substances throughout the different parts of the plant. The two types of vascular tissue are xylem and phloem. Xylem transports water and some soluble nutrients, while phloem transports organic compounds the plant uses as food, particularly sucrose. Vascular tissues are long and thin, and form cylinders that nutrients are transported through like pipes. Vascular tissue is also involved with two types of meristems, which are tissues that contain undifferentiated cells that are used during a plant’s growth. The meristems accompanying vascular tissue are the cork cambium and the vascular cambium. These meristems are associated with the growth of the plant’s vascular tissues.
Ground
Ground tissue is made up of all cells that are not vascular or dermal (having to do with the epidermis; see below). There are three types of ground tissue: parenchyma, collenchyma, and sclerenchyma. Parenchyma cells form the “filler” tissue in plants, and perform many functions like photosynthesis, storage of starch, fats, oils, proteins, and water, and repairing damaged tissue. Collenchyma tissue is made up of long cells with irregularly thick walls that provide structural support to the plant. Plants that grow in windy areas have thicker walls of collenchyma tissue. Sclerenchyma is also supporting tissue, but it is made of dead cells. There are two types of sclerenchyma: fibers and sclereids. Fibers are long, slender cells, while sclereids are star-shaped with thick cell walls. Sclerenchyma fibers make up fabrics such as hemp and flax.