Epithelial Tissue Epithelial tissue covers body surfaces and lines body cavities. lines, protects, and forms glands. moves materials in, out, or around the body. protects the internal environment secretes a product. Three types of epithelium: Squamous epithelium - flattened cells. Cuboidal epithelium - cube-shaped cells. Columnar epithelium - elongated cells.
Stratified or not Epithelium can be simple or stratified. Simple - only a single cell layer Stratified - more than one layer of cells. Pseudostratified epithelium - a single layer with cells shaped so they look like two layers. Single layer of simple cuboidal epithelium lining either side of a tubule.
Simple Squamous Epithelium single layer of flattened cells resting on connective tissues. found in thin barriers where exchange of nutrients, wastes, or respiratory gases occurs. Alveoli and capillaries of lungs where gas exchange occurs Kidney glomerulus and tubules where filtration and diffusion processes form urine Capillaries where diffusion and osmosis occur
Cuboidal Epithelium More volume means they can accomplish more complex functions such as absorption and secretion. Secretion cells of glands Lining of the ducts of most exocrine glands Lining of kidney tubules
Simple Columnar Epithelium largest cytoplasmic volumes of all epithelia, so they possess the organelle density and energy to accomplish the most complex and efficient secretion or absorption functions. Simple columnar epithelia with microvilli line the small intestine Ciliated types in small bronchioles of the respiratory tract and in fallopian tubes of the female reproductive tract. Unicellular goblet cell, is a specialized columnar cell of mucous membranes that secretes mucous for protection. Lines ducts of exocrine glands and large tubules/collecting ducts of the kidney
Pseudostratified epithelium “Falsely stratified“ cells are columnar (tall and thin and intertwine. Cells rest on basement membrane. Nuclei appear at various levels but no distinct layering. Most common in upper or lower respiratory tract as ciliated types. Beat in rhythm to propel mucous along cell surfaces to trap dust, debris and microbes (“ciliary escalator”). Non-ciliated cells found in ducts of larger glands or the male urethra
Connective Tissue Connective cells separated from one another by non- cellular matrix. The matrix may be solid (bone), soft (loose connective tissue), or liquid (blood). Two types of connective tissue: Loose Connective Tissue (LCT) and Fibrous Connective Tissue (FCT). Fibroblasts (FCT) separated by a collagen fiber- containing matrix that provides elasticity and flexibility. LCT is beneath epithelium in skin and many internal organs, such as lungs, arteries and the urinary bladder. Also forms a protective layer over muscle, nerves, and blood vessels.
More Connective Tissue Adipose tissue - enlarged fibroblasts storing fats - facilitates energy storage and insulation. Fibrous Connective Tissue has many fibers of collagen closely packed together. FCT occurs in tendons, which connect muscle to bone. Ligaments are also composed of FCT - connect bone to bone at a joint. Cartilage and bone - "rigid" connective tissues. Cartilage has structural proteins deposited in the matrix between cells.
Muscle Tissue facilitates movement of the animal by contraction of individual muscle cells (referred to as muscle fibers). Three types of muscle fibers occur in animals (the only taxonomic kingdom to have muscle cells): skeletal (striated) smooth cardiac
Striated Muscle Striated fibers: alternating bands perpendicular to the long axis of the cell. Function with bones to produce voluntary muscle movements. The bands are areas of actin and myosin deposition in the cells.
Smooth Muscle Found in intestines, linings of blood vessels, etc. Smooth fibers lack the banding, although actin and myosin still occur. Function in involuntary movements (such as peristalsis, breathing, secretion, ejaculation, birth, and certain reflexes). Smooth muscle fibers are spindle shaped cells that form masses.
Cardiac Muscle Cardiac fibers are a type of striated muscle found only in the heart. The cell has a forked shape, usually with the nucleus near the center of the cell. The cells are usually connected to each other by “intercalated” disks.
Nervous Tissue Receives stimulus and controls the response to that stimulus. Nerve cells are called neurons. Each neuron has a cell body, an axon, and many dendrites. Nervous tissue is composed of two main cell types: neurons and glial cells. Neurons transmit nerve messages. Glial cells are in direct contact with neurons and often surround them.
Functional Neuron Neuron - functional unit of nervous system (100 billion neurons in brain alone!) Three parts. Dendrites receive information from another cell and transmit the message to the cell body. The Cell Body contains the nucleus, mitochondria and other organelles typical of eukaryotic cells. The Axon conducts messages away from the cell body.
For Fun This website has a lot of games and puzzles, etc. related to tissues.