Human Tissue - Lecture Note

Human Tissue In the human body there are four groups of tissues known as basic tissues, namely epithelial tissue, muscular tissue (muscle), nervous tissue (nervus), and connective tissue (connective). Epithelial Tissue Epithelial tissue is cells that cover the surface of the body, including blood vessels and airway cells. Epithelial tissue is divided into two main groups, each consisting of various varieties. All epithelium lies on a homogeneous material called the lining (base) membrane. Types of epithelial tissue, namely: 1. Simple epithelium, this group only consists of one layer of cells and can be further divided into three varieties. 2. Squashed epithelium, consisting of fine thin sheets arranged close together, as in a mosaic painting or as on a floor. These cells are found in places where the surface is very smooth, such as the lining of the heart (serous membrane, lining of blood vessels and lymph). 3. Cylindrical epithelium, formed by a single layer of cells and lining the ducts of most glands, almost the entire digestive tract interspersed with cup-shaped cells in between and also lining some parts of the urogenital tract. 4. Hairy epithelium, these cells can be found in the respiratory tract and its branches, such as the frontal sinus and maxillary sinus. These cells also line the fallopian tubes and parts of the uterus and brain ventricles. 5. Compound epithelium, consisting of more than one layer of cells. Stratified epithelium forms the epidermal layer (epidermis) of the skin. The function of epithelial tissue is to protect the organs it covers, as organs of secretion and absorption. Epithelial tissue prevents damage to the underlying tissue, loss of fluid from this layer, and also the entry of fluid into the structures it covers. Muscles tissues Muscles are tissues that have the special ability to contract to cause movement. Muscles consist of cylindrical fibers that have the same properties as cells from other tissues. Everything is tied into small bundles of fibers by a type of connective tissue that contains contractile elements. There are three types of muscles, namely as follows. 1. Skeletal muscles (striated muscles, skeletal muscles, or voluntary muscles). Each muscle fiber has transverse lines which are depicted alternating between light and dark colors. Each fiber is formed by a number of myo-fibrils and is surrounded by a smooth membrane, namely the sarcolemna (muscle membrane). 2. Smooth muscles (unlined muscles, smooth muscles, involuntary muscles). This type can contract without nerve stimulation, although in most places in the body its activities are under the control of autonomic (involuntary) nerves. 3. Cardiac muscle, found only in the heart. Heart muscle has the special ability to carry out automatic and rhythmic contractions without depending on the presence or absence of nerve stimulation. This kind of action is called myogenic, which differentiates it from neurogenic. Connective tissue As the name suggests, connective tissue functions to bind body tissues and organs. An example of this tissue is blood tissue. Nervous Tissue Nervous tissue is a network that functions to regulate muscle and organ activity receivings timuli. 1. gray elements, which form nerve cells, 2. white elements, namely nerve fibers, 3. neuroglia, a type of support cell found only in the nervous system and which collects and supports nerve cells and nerve fibers.