Hámszövetek

Hámszövetek, also known as epithelial tissues, form a continuous sheet of cells that covers the external surfaces of the body and lines internal cavities and organs. These tissues are characterized by their tightly packed cells with little intercellular space. Hámszövetek have several key functions, including protection, secretion, absorption, and excretion. They also play a role in sensory reception and diffusion.

There are several ways to classify hámszövetek. One classification is based on the number of cell layers. Simple epithelia consist of a single layer of cells, while stratified epithelia are composed of multiple layers. Pseudostratified epithelia appear to have multiple layers but are actually a single layer of cells of varying heights. Another classification is based on the shape of the cells. Squamous cells are flattened, cuboidal cells are cube-shaped, and columnar cells are taller than they are wide.

Specific types of hámszövetek are named according to their structure and location. For example, simple squamous epithelium lines blood vessels and the air sacs of the lungs, facilitating diffusion. Simple cuboidal epithelium is found in kidney tubules and glands, involved in secretion and absorption. Simple columnar epithelium lines the digestive tract, aiding in absorption and secretion, and may have cilia for movement. Stratified squamous epithelium forms the outer layer of the skin, providing protection. Transitional epithelium, found in the urinary tract, can stretch and recoil. Glandular epithelia are specialized for secretion and can be exocrine (secreting into ducts) or endocrine (secreting hormones directly into the bloodstream).