Epithelial Tissue
Epithelial tissue is one of the four fundamental types of tissue in the body. It forms the
coverings and
linings of organs and body cavities, providing a protective barrier. Epithelial cells are tightly packed, forming continuous sheets, and they exhibit polarity with distinct apical and basal surfaces.
What are the functions of epithelial tissue? This tissue type performs several functions, including protection, absorption, secretion, and sensation. It acts as a barrier against mechanical injury, pathogens, and fluid loss. Glandular epithelium is specialized for
secretion of hormones, enzymes, and other substances.
How is epithelial tissue classified? Epithelial tissue is classified based on the number of cell layers and cell shape. Simple epithelium consists of a single cell layer, while stratified epithelium has multiple layers. It can also be classified as squamous (flat), cuboidal (cube-shaped), or columnar (tall and column-shaped).
Connective Tissue
Connective tissue provides structural and metabolic support for other tissues and organs. It is characterized by an abundance of extracellular matrix, which includes fibers and ground substance, in which cells are embedded. This matrix is key to its diverse functions.
What are the main components of connective tissue? The three main components are cells, fibers, and ground substance. The cell types include fibroblasts, adipocytes, macrophages, and mast cells. The fibers, such as collagen, elastic, and reticular fibers, provide strength and elasticity.
How is connective tissue classified? It is classified into loose connective tissue, dense connective tissue, cartilage, bone, and blood. Each subtype has a unique composition and function, such as support, binding, storage, and transport of nutrients and waste products.Muscle Tissue
Muscle tissue is specialized for contraction, enabling movement and force generation. It is composed of cells known as muscle fibers, which contain actin and myosin filaments that slide past each other to produce contraction.
What are the types of muscle tissue? There are three types: skeletal, cardiac, and smooth muscle. Skeletal muscle is voluntary and striated, allowing for conscious movement. Cardiac muscle, found in the heart, is involuntary and striated, while smooth muscle, found in walls of hollow organs, is involuntary and non-striated.
What are the distinctive features of each muscle type? Skeletal muscle fibers are multinucleated and arranged in parallel bundles. Cardiac muscle fibers are branched and connected by intercalated discs, enabling synchronized contraction. Smooth muscle fibers are spindle-shaped with a single nucleus.Nervous Tissue
Nervous tissue is responsible for receiving stimuli and transmitting electrical impulses throughout the body. It consists of neurons and supporting cells called glia, which provide structural and metabolic support.
How do neurons function in nervous tissue? Neurons are specialized cells that generate and conduct nerve impulses. They consist of a cell body, dendrites, and an axon. Dendrites receive signals, while the axon transmits them to other neurons or effector cells.
What is the role of glial cells? Glial cells, including astrocytes, oligodendrocytes, and microglia in the
central nervous system, and Schwann cells in the
peripheral nervous system, support neurons by providing nutrients, maintaining homeostasis, forming myelin, and participating in immune responses.
