HISTOLOGY: Study of tissues that make up the organs in the organ systems Ch. 3 Notes Part A

Organization of the Human Body

Tissue Types Four different types of tissues form your body's organs. These major types of tissues are – epithelial – connective – muscle – nervous tissues

Characteristics of Epithelial Tissues cover or line structures in the body cover parts of the body exposed to air, or line a cavity or tube (free surface

Characteristics of Epithelial Tissues Continued They cover body surfaces. They line body cavities (like the abdomen), hollow organs (like the heart or stomach), or tubes (like blood vessels or intestines). Their cells are tightly packed together. Their cells are attached to underlying connective tissue by a basement membrane. Their cells don't have their own blood supply. Their cells reproduce easily and quickly.

Functions of Epithelial Tissue ProtectionEx. Skin Secrete substances like mucusEx. Nose Allow gases and nutrients to pass from one structure to anotherEx. Lungs Works to filter bloodEx. Kidneys Forms glands Excrete waste products Component of sensory organs

Naming of Epithelial Tissues Each type of epithelial tissue is named based on the shape of its cells and the number of layers of cells within that tissue. If the tissue has more than one layer of cells, the shape part of the name is based on the top layer.

Naming of Epithelial Tissues Name Based on ShapeDescription SquamousCells are flat and look like tiles. Cuboidal Cells are shaped like boxes with relatively equal horizontal and vertical sides. ColumnarCells are shaped like columns with longer vertical sides.

Naming of Epithelial Tissues Name Based on LayersDescription SimpleSingle layer of cells. StratifiedMore than one layer of cells. Pseudostratified Single layer of cells, but cells are uneven, so it looks like there's more than one layer. Transitional Several layers of cells when the tissue is relaxed, but layers decrease in number as tissue is stretched.

Examples of Epithelial Tissues Simple Squamous Epithelial Tissue – found in the lungs, the walls of the smallest blood vessels (capillaries), and in the kidneys. This tissue has only one layer of flat, tile-like cells. That makes sense because this is where gas exchange and filtration of wastes occur, so the tissue needs to be very thin.

Examples of Epithelial Tissues Simple squamous epithelial tissue

Examples of Epithelial Tissues Simple Cuboidal Epithelial Tissue – found in many of your glands, like the ovaries (if you're a female), salivary glands, thyroid gland, and pancreas, plus little tubules in your kidneys – secretes and absorbs substances – for example, the epithelial tissue in the thyroid gland secretes the hormone thyroxine.

Examples of Epithelial Tissues Simple cuboidal epithelial tissue

Examples of Epithelial Tissues Simple Columnar Epithelial Tissue – lines your uterus (again, if you're a female), stomach, and intestines. – absorbs substances like nutrients from the food you eat – microvilli - form a brush-like surface to increase the amount of surface area to allow you to absorb more nutrients – goblet cells - secrete mucus in the digestive tract to prevent infection. Protects your tissue from being eaten away by the strong chemicals found in your stomach and intestines.

Examples of Epithelial Tissues Simple columnar epithelial tissue

Examples of Epithelial Tissues Stratified Squamous Epithelial Tissue – forms the outer layer of the skin and lines the mouth, vagina, and anal canal

Examples of Epithelial Tissues Stratified squamous epithelial tissue

Examples of Epithelial Tissues Stratified Cuboidal Epithelial Tissue – lines the larger ducts of a woman's mammary glands (the glands that produce milk), salivary glands, sweat glands, and the pancreas

Examples of Epithelial Tissues Stratified cuboidal epithelial tissue

Examples of Epithelial Tissues Pseudostratified Columnar Epithelial Tissue – lines the passageways of the respiratory system – goblet cells that secrete mucus – extensions called cilia.

Examples of Epithelial Tissues Pseudostratified columnar epithelial tissue

Examples of Epithelial Tissues Transitional Epithelial Tissue – allows your bladder to stretch to hold urine

Examples of Epithelial Tissues Transitional epithelial tissue