Ch 4: Tissue Groups of cells that are similar in structure and perform a common or related functions are called TISSUE The study of tissue, or histology, complements the study of gross anatomy. Together they provide the structural basis for understanding organ physiology.

Tissues The tissues of the human body include four major types: general function Epithelial: covering Connective: support Muscle: movement Nervous: control

Types of Tissue!!

EPITHELIAL TISSUES

EPITHELIAL TISSUES Epithelial Tissue: is a sheet of cells that covers a body surface or lines a body cavity Nearly all substances received or given off by the body must pass through an epithelium layer.

EPITHELIAL TISSUES Epithelial Tissue lacks of blood vessels, contains little intercellular material and are continually being replaced They function in protection, secretion, absorption, filtration, excretion, and sensory reception.

EPITHELIAL TISSUES Epithelium Tissue has many characteristics that separate it from other tissue types ET has Polarity- which means it has an apical surface (near the top) and a basal surface (near the bottom) Specialized Contacts Supported by connective tissue.

EPITHELIAL TISSUES Each Epithelium Tissue is given two names. The first name indicates the number of cell layers present. Simple- one layer Stratified- more than one layer The second describes the shape of its cells Squamous, cuboidal, and columnar. .

EPITHELIAL TISSUES .

Simple Squamous Epithelium This tissue consists of a single layer of thin, flattened cells through which substances can pass easily. So delicate they can easily be damaged. Common site of diffusion and osmosis. Its functions in the exchange of gases in the lungs Lines the air sacs of the lungs (gas exchange), forms the walls of the capillaries, lines the insides of blood vessels and lymph vessels. Covers the membrane that line body cavities. EX: Cheek Cells

Simple Squamous Epithelium

Simple Squamous Epithelium

Simple Cuboidal Epithelium This tissue consists of a single layer of cube-shaped cells. Usually have a centrally located spherical nuclei It carries on secretion and absorption. Secretes glandular products. Covers the ovaries, lines the kidneys, tubules and ducts of certain glands like pancreas and the liver.

Simple Cuboidal Epithelium

Simple Cuboidal Epithelium

Simple Columnar Epithelium The tissue is composed of a single layer of elongated cells whose nuclei are usually at about the same level, near the basement membrane. Some have cilia some do not Secretes and absorbs…this tissue is thick!! This tissue lines uterus and portions of the digestive tract like small/large intestines and stomach.

Simple Columnar Epithelium

Simple Columnar Epithelium

Simple Columnar Epithelium

Pseudostratified Columnar Epithelium They appear stratified but are NOT, They appear to have two or more nuclei but they each reach the basement level. Goblet cells scattered throughout the tissue that secret mucus, which the cilia sweep away. It lines tubes of the respiratory system. The mucus and cilia created by this tissue trap the dust and microorganisms that enter the airway.

Pseudostratified Columnar Epithelium “C” the nuclei appear at various levels giving it the stratified appearance “B” the cilia can easily be seen

Pseudostratified Columnar Epithelium

Pseudostratified Columnar Epithelium

Stratified Squamous Epithelium Named for the shape of the cells,…consists of many layers, relatively thick. Cells nearer the surface are flat where as the deeper are cuboidal and columnar. Tissue can contain Keratin, which is a protein that accumulates and protect the underlying tissue. Epidermis-outer most layer of the skin Also lines the skin and lines the oral cavity, throat, vagina, and anal canal.

Stratified Squamous Epithelium Observe that the surface cells (at B) are flattened (are squamous).

Stratified Squamous Epithelium

Stratified Cuboidal Epithelium This tissue is composed of two or thee layers of cube-shaped cells. It lines the larger ducts of the mammary glands sweat glands, salivary glands, and pancreas. Forms the lining of ovarian follicles and seminiferous tubules It functions in protection.

Transitional Epithelium This tissue is specialized to change in response to tension.. Transition epithelium is unstretched and consists of many layers when the organs wall contract the tissue stretches and appears thinner when the organ is distended. Forms the lining of the urinary bladder and lines the ureters and part of the urethra.

Transitional Epithelium

Transitional Epithelium